Sodium alginate/guar gum based nanocomposite film incorporating β-Cyclodextrin/persimmon pectin-stabilized baobab seed oil Pickering emulsion for mushroom preservation

The poor biological, mechanical and water-resistance properties of sodium alginate/guar gum film (SG) limit its application in food preservation. To overcome this disadvantage, we added β-Cyclodextrin/persimmon pectin-stabilized baobab seed oil Pickering emulsion (BOPE) to enhance the mechanical and water resistance properties of SG film, and added green synthesized silver nanoparticles (AgNPS) and Lycium ruthenicum extract (LA) to improve the biological properties of the film. The properties of BOPE was optimized using Box-Behnken design (BBD). Scanning electron microscope and Fourier transform infrared results revealed the change of structure and molecular interaction in the SG film after the addition of AgNPS, LA, and optimized BOPE. The 2.0%BOPE-loaded film containing AgNPS/LA with the enhanced mechanical, barrier, BO retention, and biological properties not only improved the preservation effect on mushroom (A. bisporus), but also maintained structural stability. Thus, the 2.0%BOPE-loaded SG/LA/AgNPS film has considerable potential in active packaging applications.

Optimization of green silver nanoparticles as nanofungicides for management of rice bakanae disease

Rice bakanae, a devastating seed-borne disease caused by Fusarium species requires a more attractive and eco-friendly management strategy. The optimization of plant-mediated silver nanoparticles (AgNPs) as nanofungicides by targeting Fusarium species may be a rational approach. In this study, Azadirachta indica leaf aqueous extract-based AgNPs (AiLAE-AgNPs) were synthesized through the optimization of three reaction parameters: A. indica leaf amount, plant extract-to-AgNO3 ratio (reactant ratio), and incubation time. The optimized green AgNPs were characterized using ultraviolet-visible light (UV-Vis) spectroscopy, field emission scanning electron microscopy (FESEM) with energy dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS), and powder X-ray diffraction (XRD) techniques. The optimal conditions for producing spherical, unique, and diminutive-sized AgNPs ranging from 4 to 27 nm, with an average size of 15 nm, were 2 g AiLAE at a 1:19 ratio (extract-to-AgNO3) and incubated for 4 h. Fusarium isolates collected from infected soils and identified as F. fujikuroi (40) and F. proliferatum (58 and 65) by PCR were used for seed infestation. The AgNPs exhibited concentration-dependent mycelial growth inhibition with EC50 values ranging from 2.95 to 5.50 μg/mL. The AgNPs displayed exposure time-dependent seed disinfectant potential (complete CFU reduction in F. fujikuroi (40) and F. proliferatum (58) was observed at a concentration of 17.24 μg/mL). The optimized green AgNPs were non-toxic to germinating seeds, and completely cured bakanae under net-house conditions, suggesting their great nano-fungicidal potency for food security and sustainable agriculture.

Plant extract preparation and green synthesis of silver nanoparticles using Swertia chirata: Characterization and antimicrobial activity against selected human pathogens

Herbal medicinal plants have been used for centuries in traditional medicine, and it is interesting to see how modern research has identified the active compounds responsible for their therapeutic effects. The green synthesis of silver nanoparticles using herbal medicinal plants, such as Swertia chirata, is particularly noteworthy due to its antimicrobial properties. In the current study, the Swertia chirata plant was collected for the first time from the region of Murree, Punjab, Pakistan. After collection, extracts were prepared in different solvents (ethanol, methanol, chloroform, and distilled water), and silver nanoparticles were synthesized by reducing silver nitrate (AgNO3). The UV-visible spectrophotometer, SEM, and EDX were used to characterize the synthesized nanoparticles in terms of their size and shape. The phytochemical analysis of crude extract was performed to determine the presence of different kinds of phytochemicals. The antibacterial activity of plant extracts and the silver nanoparticles were then assessed using the agar well diffusion method against various pathogenic bacteria. The results showed that the plant contains several phytochemicals with remarkable antioxidant potential. The antibacterial analysis revealed that silver nanoparticles and the plant extracts exhibited a significant zone of inhibition against human pathogenic bacteria (Escherichia coli, S. capitis, B. subtilis, and Pseudomonas aeruginosa) as compared to the cefixime and norfloxacin. This implies that the nanoparticles have the potential to be used in nano-medicine applications, such as drug delivery systems, as well as for their antibacterial, antifungal, and antiviral activities. Additionally, the development and application of materials and technologies at the nanometer scale opens possibilities for the creation of novel drugs and therapies. Overall, the study highlights the promising potential of herbal medicinal plants found in Murree, Punjab, Pakistan, and green-synthesized silver nanoparticles in various fields of medicine and nanotechnology.

Silver nanoparticle-functionalized melamine-formaldehyde aerogel for online in-tube solid-phase microextraction of polycyclic aromatic hydrocarbons followed by HPLC-DAD analysis

Based on the π-metal interaction between silver nanoparticles (AgNPs) and aromatic compounds, AgNPs were in-situ grown to melamine-formaldehyde (MF) aerogel for improving the extraction performance to polycyclic aromatic hydrocarbons (PAHs). The AgNPs/MF aerogel was regulated through varing the concentration of reactants, and characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray powder diffraction. As a new extraction coating, the AgNPs/MF aerogel was coated to stainless-steel wires for in-tube solid-phase microextraction (IT-SPME). The extraction effects of MF aerogels before and after the modification of AgNPs were compared, and the AgNPs greatly improved the extraction ability for PAHs reaching to 166.4 %. Combining IT-SPME with high performance liquid chromatographic detection, an online analytical system was constructed. Furthermore, the sampling volume and rate, concentration of organic solvent, and desorption time were optimized factor by factor. The online analytical method with low detection limits (0.003-0.010 μg L-1) and efficient enrichment factors (1998-3237) for PAHs was established, which fastly detected trace level of PAHs in drinking and environmental water samples. Compared with other methods, the method was comparable or better in the detection limit and linear range, indicating prospective application of the AgNPs/MF aerogel for sample preparation.

Unveiling the antibacterial and antifungal potential of biosynthesized silver nanoparticles from Chromolaena odorata leaves

This research investigates the biogenic synthesis of silver nanoparticles (AgNPs) using the leaf extract of Chromolaena odorata (Asteraceae) and their potential as antibacterial and antifungal agents. Characterization techniques like ultraviolet-visible, Fourier transform infrared (FTIR), Dynamic light scattering and zeta potential (DLS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy (FESEM-EDX) confirmed the formation of spherical (AgNPs). UV-vis spectroscopy reaffirms AgNP formation with a peak at 429 nm. DLS and zeta potential measurements revealed an average size of 30.77 nm and a negative surface charge (- 0.532 mV). Further, XRD analysis established the crystalline structure of the AgNPs. Moreover, the TEM descriptions indicate that the AgNPs are spherical shapes, and their sizes ranged from 9 to 22 nm with an average length of 15.27 nm. The X-ray photoelectron spectroscopy (XPS) analysis validated the formation of metallic silver and elucidated the surface state composition of AgNPs. Biologically, CO-AgNPs showed moderate antibacterial activity but excellent antifungal activity against Candida tropicalis (MCC 1559) and Trichophyton rubrum (MCC 1598). Low MIC values (0.195 and 0.390 mg/mL) respectively, suggest their potential as effective antifungal agents. This suggests potential applications in controlling fungal infections, which are often more challenging to treat than bacterial infections. Molecular docking results validated that bioactive compounds in C. odorata contribute to antifungal activity by interacting with its specific domain. Further research could pave the way for the development of novel and safe antifungal therapies based on biogenic nanoparticles.

Methylene blue@silver nanoprisms conjugates as a strategy against Candida albicans isolated from balanoposthitis using photodynamic inactivation

Balanoposthitis can affect men in immunocompromised situations, such as HIV infection and diabetes. The main associated microorganism is Candida albicans, which can cause local lesions, such as the development of skin cracks associated with itching. As an alternative to conventional treatment, there is a growing interest in the photodynamic inactivation (PDI). It has been shown that the association of photosensitizers with metallic nanoparticles may improve the effectiveness of PDI via plasmonic effect. We have recently shown that the association of methylene blue (MB), a very known photosensitizer, with silver prismatic nanoplatelets (AgNPrs) improved PDI of a resistant strain of Staphylococcus aureus. To further investigate the experimental conditions involved in PDI improvement, in the present study, we studied the effect of MB concentration associated with AgNPrs exploring spectral analysis, zeta potential measurements, and biological assays, testing the conjugated system against C. albicans isolated from a resistant strain of balanoposthitis. The AgNPrs were synthesized through silver anisotropic seed growth induced by the anionic stabilizing agent poly(sodium 4-styrenesulfonate) and showed a plasmon band fully overlapping the MB absorption band. MB and AgNPrs were conjugated through electrostatic association and three different MB concentrations were tested in the nanosystems. Inactivation using red LED light (660 nm) showed a dose dependency in respect to the MB concentration in the conjugates. Using the highest MB concentration (100 µmol⋅L-1) with AgNPr, it was possible to completely inactivate the microorganisms upon a 2 min irradiation exposure. Analyzing optical changes in the conjugates we suggest that these results indicate that AgNPrs are enhancers of MB photodynamic action probably by a combined mechanism of plasmonic effect and reduction of MB dimerization. Therefore, MBAgNPrs can be considered a suitable choice to be applied in PDI of resistant microorganisms.

Harnessing nature's potential: Alpinia galanga methanolic extract mediated green synthesis of silver nanoparticle, characterization and evaluation of anti-neoplastic activity

With the advent of nanotechnology, the treatment of cancer is changing from a conventional to a nanoparticle-based approach. Thus, developing nanoparticles to treat cancer is an area of immense importance. We prepared silver nanoparticles (AgNPs) from methanolic extract of Alpinia galanga rhizome and characterized them by UV-Vis spectrophotometry, Fourier transform Infrared (FTIR) spectroscopy, Zetasizer, and Transmission electron Microscopy (TEM). UV-Vis spectrophotometry absorption spectrum showed surface plasmon between 400 and 480 nm. FTIR spectrum analysis implies that various phytochemicals/secondary metabolites are involved in the reduction, caping, and stabilization of AgNPs. The Zetasier result suggests that the particles formed are small in size with a low polydispersity index (PDI), suggesting a narrow range of particle distribution. The TEM image suggests that the particles formed are mostly of spherical morphology with nearly 20-25 nm. Further, the selected area electron diffraction (SAED) image showed five electron diffraction rings, suggesting the polycrystalline nature of the particles. The nanoparticles showed high anticancer efficacy against cervical cancer (SiHa) cell lines. The nanostructures showed dose-dependent inhibition with 40% killing observed at 6.25 µg/mL dose. The study showed an eco-friendly and cost-effective approach to the synthesis of AgNPs and provided insight into the development of antioxidant and anticancer agents.

Green synthesis of silver and gold nanoparticles in Callistemon viminalis extracts and their antimicrobial activities

In the current study, the bottlebrush [Callistemon viminalis (Sol. ex Gaertn.) G. Don] plant was selected for the green synthesis of silver (Ag) and gold (Au) nanoparticles and to evaluate its antibacterial and antifungal activities. Phytochemical screening of C. viminalis confirmed the presence of alkaloids, anthraquinones, saponins, tannins, betacyanins, phlobatanins, coumarins, terpenoids, steroids, glycosides, and proteins. To characterize the synthesized Ag and Au NPs, UV-Visible spectroscopy, FTIR spectroscopy for functional group identification, field emission scanning electron microscopy (FE-SEM) for particle size, and elemental analysis were performed using EDX. The UV-Visible absorption spectra of the green-synthesized Ag and Au nanoparticles were found to have a maximum absorption band at 420 nm for Ag NPs and 525 nm for Au NPs. FE-SEM analysis of the synthesized NPs revealed a circular shape with a size of 100 nm. Elemental analysis was performed for the synthesis of Ag and Au NPs, which confirmed the purity of the nanoparticles. The greenly synthesized Ag and Au NPs were also evaluated for their anti-bacterial and anti-fungal activities, which exhibited prominent inhibition activities against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Candida albicans, C. krusei, Aspergillus sp., and Trichoderma species. The highest zone of inhibition 15.5 ± 0.75 and 15 ± 0.85 mm was observed for Ag NPs against E. coli and P. aeruginosa. Similarly, Trichoderma sp. and Aspergillus sp. were inhibited by Ag NPs up to 13.5 ± 0.95 and 13 ± 0.70 mm. This work will open doors for the development of new antimicrobial agents using green chemistry.

Mitophagy protects against silver nanoparticle-induced hepatotoxicity by inhibiting mitochondrial ROS and the NLRP3 inflammasome

Silver nanoparticles (AgNPs) have wide clinical applications because of their excellent antibacterial properties; however, they can cause liver inflammation in animals. Macrophages are among the main cells mediating inflammation and are also responsible for the phagocytosis of nanomaterials. The NLRP3 inflammasome is a major mechanism of inflammation, and its activation both induces cytokine release and triggers inflammatory cell death (i.e., pyroptosis). In previous studies, we demonstrated that mitophagy activation plays a protective role against AgNP-induced hepatotoxicity. However, the exact molecular mechanisms underlying these processes are not fully understood. In this study, we demonstrate that AgNP exposure induces NLRP3 inflammasome activation, mitochondrial damage and pyroptosis in vivo and in vitro. NLRP3 silencing or inhibiting mitochondrial reactive oxygen species (ROS) overproduction reduces PINK1-Parkin-mediated mitophagy. Meanwhile, the inhibition of mitophagy ROS production, mitochondrial, NLRP3-mediated inflammation, and pyroptosis in RAW264.7 cells were more pronounced than in the control group. These results suggest that PINK1-Parkin-mediated mitophagy plays a protective role by reducing AgNP-induced mitochondrial ROS and subsequent NLRP3 inflammasome activation.

Comprehensive antifungal investigation of green synthesized silver nanoformulation against four agriculturally significant fungi and its cytotoxic applications

The present study reports the green synthesis of silver nanoparticles (AgNPs) in powder form using the leaf extract of Azadirachta indica. The synthesis of AgNPs was confirmed by UV-vis spectroscopy, FTIR, XRD, FESEM, and EDX. The synthesized AgNPs were in a powdered state and dispersed completely in 5% polyethylene glycol (PEG) and demonstrated prolonged shelf life and enhanced bioavailability over a year without any aggregation. The resulting silver nanoformulation demonstrated complete inhibition against Sclerotinia sclerotiorum and Colletotrichum falcatum and 68% to 80% inhibition against Colletotrichum gloeosporioides and Rhizoctonia solani respectively, at 2000 ppm. The EC50 values determined through a statistical analysis were 66.42, 157.7, 19.06, and 33.30 ppm for S. sclerotiorum, C. falcatum, C. gloeosporioides, and R. solani respectively. The silver nanoformulation also established significant cytotoxicity, with a 74.96% inhibition rate against the human glioblastoma cell line U87MG at 250 ppm. The IC50 value for the cancerous cell lines was determined to be 56.87 ppm through statistical analysis. The proposed silver nanoformulation may be used as a next-generation fungicide in crop improvement and may also find application in anticancer investigations. To the best of our knowledge, this is also the first report of silver nanoformulation demonstrating complete inhibition against the economically significant phytopathogen C. falcatum.

Efficacy of silver nanoparticles against Trichinella spiralis in mice and the role of multivitamin in alleviating its toxicity

Trichinellosis is a worldwide zoonotic disease. The majority of currently available anti-trichinellosis medications exhibit inadequate efficacy. The efficacy of a natively prepared new formulation of silver nanoparticles (Ag-NPs) was evaluated in the treatment of Trichinella spiralis (T. spiralis) infection in mice alone and combined with multivitamin-mineral (MM). After investigating the product's biological and pharmacological characteristics, its therapeutic dose was estimated to be Ag-NPs at 21.5 mg/kg B.W. This dose was orally inoculated to experimentally infected mice at 3-5 days post-inoculation (dpi) against the mature worms, at 8-10 dpi against the newborn larvae, and at 33-35th dpi against the encapsulated larvae. Each treatment's efficacy was assessed by scarifying control and treated mice 3 days post-treatment. The drug alone or in supplement form has a high trichinocidal effect exceeding that of the reference drug. Early treatment (3-5 dpi) by Ag-NPs or Ag-NPs + MM and albendazole revealed high efficacy against the intestinal stage, reaching 93.3%, 94.7%, and 90.6% for the three treatments, respectively. The materials causing a significant (P-value < 0.001) decrease in the mean encapsulated larvae reached 86.61%, 89.07%, and 88.84%/gm of muscles using the three treatments, respectively. Moreover, all larvae extracted from Ag-NPs-treated groups failed to induce infection post-inoculation in new mice. Additionally, combining the material with MM proved to overcome the reversible adverse effects of silver material on the estimated redox parameters and liver and kidney biomarkers, denoting its ability to alleviate Ag-NP toxicity. In conclusion, the high trichinocidal effect of Ag-NPs against the adult and encapsulated larvae during a short inoculation period introduced Ag-NPs as an alternative to other nematicidal drugs.

Silver nanoparticles induced synaptic degeneration via Ca2+/CaMKII signal and Drp1-dependent mitochondrial disorder in HT22 cells

Silver nanoparticles (AgNPs) have been widely used in biomedicine and cosmetics, increasing their potential risks in neurotoxicity. But the involved molecular mechanism remains unclear. This study aims to explore molecular events related to AgNPs-induced neuronal damage by RNA-seq, and elucidate the role of Ca2+/CaMKII signal and Drp1-dependent mitochondrial disorder in HT22 cells synaptic degeneration induced by AgNPs. This study found that cell viabilities were decreased by AgNPs in a dose/time-dependent manner. AgNPs also increased protein expression of PINK1, Parkin, synaptophysin, and inhibited PGC-1α, MAP2 and APP protein expression, indicating AgNPs-induced synaptic degeneration involved in disturbance of mitophagy and mitochondrial biogenesis in HT22 cells. Moreover, inhibition of AgNPs-induced Ca2+/CaMKII activation and Drp1/ROS rescued mitophagy disturbance and synaptic degeneration in HT22 cells by reserving aforementioned protein express changes except for PGC-1α and APP protein. Thus, AgNPs-induced synaptic degeneration was mediated by Ca2+/CaMKII signal and Drp1-dependent mitochondrial disorder in HT22 cells, and mitophagy is the sensitive to the mechanism. Our study will provide in-depth molecular mechanism data for neurotoxic evaluation and biomedical application of AgNPs.

Sensitive detection of dextromethorphan hydrobromide based on portable Raman spectrometer and CuO@AgNPs nano composite SERS substrate

A highly sensitive surface-enhanced Raman spectroscopy approach was established for the detection of dextromethorphan hydrobromide (DXM) utilizing nano CuO modified silver nanoparticles (CuO@AgNPs) as substrate. Ultraviolet visible spectra (UV-vis), X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterized the synthesized CuO@AgNPs. UV-vis and fourier transform infrared (FT-IR) were adopted to investigate the interaction between DXM and CuO@AgNPs. The optimal experimental conditions (the dosages of CuO@AgNPs and NaCl as well as mixing time) were explored. The enhancement factor (EF) was 1.71 × 106. The linear relationship between SERS intensity and the concentration of DXM in the range of 67 - 1000 nmol L-1 was obtained as ISERS = 25.81 c + 40398.77, and the limit of detection (LOD) was 2.12 nmol L-1 (S/N = 3). The interference of K+, Mg2+, Zn2+, Ca2+, Cu2+, Fe3+, glucose, HSA, L-tryptophan, soluble starch and ibuprofen were investigated. The method was successfully applied to test DXM in serum samples. The recovery was 99.06% - 101.51% with the relative standard deviation (RSD) of 0.74% - 3.87%.

Role of Silver Nanoparticles for the Control of Anthelmintic Resistance in Small and Large Ruminants

Helminths are considered a significant threat to the livestock industry, as they cause substantial economic losses in small and large ruminant farming. Their morbidity and mortality rates are also increasing day by day as they have zoonotic importance. Anthelmintic drugs have been used for controlling these parasites; unfortunately, due to the development of resistance of these drugs in helminths (parasites), especially in three major classes like benzimidazoles, nicotinic agonists, and macrocyclic lactones, their use is becoming very low. Although new anthelmintics are being developed, the process is time-consuming and costly. As a result, nanoparticles are being explored as an alternative to anthelmintics. Nanoparticles enhance drug effectiveness, drug delivery, and target specificity and have no resistance against parasites. Different types of nanoparticles are used, such as organic (chitosan) and inorganic (gold, silver, zinc oxide, iron oxide, and nickel oxide). One of them, silver nanoparticles (AgNPs), has unique properties in various fields, especially parasitology. AgNPs are synthesized from three primary methods: physical, chemical, and biological. Their primary mechanism of action is causing stress through the production of ROS that destroys cells, organs, proteins, and DNA parasites. The present review is about AgNPs, their mode of action, and their role in controlling anthelmintic resistance against small and large ruminants.

Fabrication of silver nanoparticles loaded acacia gum/chitosan nanogel to coat the pipe surface for sustainable inhibiting microbial adhesion and biofilm growth in water distribution systems

Biofilm formation on the inner surfaces of pipes poses significant threats to water distribution systems, increasing maintenance costs and public health risks. To address this immense issue, we synthesized a nanogel formulation comprising acacia gum (AG) and chitosan (Cs), loaded with varying concentrations of silver nanoparticles (AgNPs), for using as an antimicrobial coating material. AgNPs were synthesized using AG as a reducing and stabilizing agent, exhibiting absorbance at 414 nm. The preparation of AgNPs was proved using TEM. Bactericidal efficacy was assessed against E. coli, Klebsiella pneumoniae, Enterococcus faecalis, and Bacillus subtilis. Using the dipping coating method, two pipe materials (polypropylene (PP) and ductile iron (DI)) were successfully coated. Notably, AgNPs2@AGCsNG nanogel exhibited potent antibacterial action against a wide range of pathogenic bacteria. Toxicity tests confirmed nanogel safety, suggesting broad applications. High EC50% values underscored their non-toxic nature. This research proposes an effective strategy for biofilm prevention in water systems, offering excellent antibacterial properties and biocompatibility. AG and Cs nanogels loaded with AgNPs promise to enhance water quality, reduce maintenance prices, and protect human public health in water distribution networks.

Antibacterial Potential of Biosynthesized Silver Nanoparticles Using Berberine Extract Against Multidrug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa

The emergence of multidrug resistance in bacterial infections has limited the use of antibiotics. Helping the action of antibiotics is one of the needs of the day. Today, the biosynthesis of nanoparticles (NPs) is considered due to its safety and cost-effectiveness. In this study, we investigated the effect of biosynthesized silver nanoparticles (AgNPs) by Berberine plant extract against standard strains of multidrug-resistant (MDR) Acinetobacter baumannii and Pseudomonas aeruginosa. Utilized UV-Vis, FTIR, FESEM/EDX, XRD, DLS, and Zeta potential techniques to confirm the biosynthesis of NPs. Then, disk diffusion agar (DDA) and minimum inhibitory concentration (MIC) tests were performed using common classes of standard antibiotics and AgNPs on the mentioned bacteria. The synergistic action between AgNPs and antibiotics was evaluated by the checkerboard method. First, we obtained the confirmation results of the biosynthesis of AgNPs. According to the DDA test, both standard bacterial strains were sensitive to NPs and had an inhibition zone. Also, the MIC values showed that AgNPs inhibit the growth of bacteria at lower concentrations than antibiotics. On the other hand, the results obtained from checkerboard monitoring showed that AgNPs, in combination with conventional antibiotics, have a synergistic effect. The advantage of this study was comparing the antibacterial effect of AgNPs alone and mixed with antibiotics. The antibacterial sensitivity tests indicated that the desired bacterial strains could not grow even in low concentrations of AgNPs. This property can be applied in future programs to solve the drug resistance of microorganisms in bacterial diseases.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-023-01136-y.

Bimetallic nanoparticles and biochar produced by Adansonia Digitata shell and their effect against tomato pathogenic fungi

Adansonia digitata L. is a royal tree that is highly valued in Africa for its medicinal and nutritional properties. The objective of this study was to use its fruit shell extract to develop new, powerful mono and bimetallic nanoparticles (NPs) and biochar (BC) using an eco-friendly approach. Silver (Ag), iron oxide (FeO), the bimetallic Ag-FeO NPs, as well as (BC) were fabricated by A. digitata fruit shell extract through a reduction process and biomass pyrolysis, respectively, and their activity against tomato pathogenic fungi Alternaria sp., Sclerotinia sclerotiorum, Fusarium equiseti, and Fusarium venenatum were detected by agar dilution method. The Ag, FeO, Ag-FeONPs, and BC were characterized using a range of powerful analytical techniques such as ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform-Infra Red (FT-IR), dynamic light scatter (DLS), and zeta potential analysis. The fabricated Ag, FeO and Ag-FeO NPs have demonstrated a remarkable level of effectiveness in combating fungal strains. UV-Vis spectra ofAg, FeO, Ag-FeONPs, and BC show broad exhibits peaks at 338, 352, 418, and 480 nm, respectively. The monometallic, bimetallic NPs, and biochar have indicated the presence in various forms mostly in Spherical-shaped. Their size varied from 102.3 to 183.5 nm and the corresponding FTIR spectra suggested that the specific organic functional groups from the plant extract played a significant role in the bio-reduction process. Ag and Ag-FeO NPs exhibited excellent antifungal activity against pathogenic fungi Alternaria sp., S. sclerotiorum, F. equiseti, and F. venenatum. The current study could be a significant achievement in the field of antifungal agents since has the potential to develop new approaches for treating fungal infections.

Development and optimization of Clitoria teratea synthesized silver nanoparticles and its application to nanogel systems for wound healing

OBJECTIVE

The present research deals with sequential optimization strategy based on Central Composite Design to optimize the process variables for efficient production of Clitoria teratea (CLT) synthesized silver nanoparticles (AgNPs) using biological synthesis.

METHODS

Two substantial factors influencing the dependent variables viz UV-visible absorbance, particle size, zeta potential and polydispersity index (PDI) were identified as NaOH concentration, RH concentration, temperature as independent variables. In-vitro and ex-vivo studies of prepared CLT-AgNPs gel and marketed gel were carried out using dialysis membrane and egg membrane, respectively. In addition, antimicrobial study was also performed on the bacterial strains.

RESULTS

The particles size (114 nm), PDI (0.45), and zeta potential (-29.5 mV) of optimized formulation were found, respectively. In-vitro profile of AgNPs from prepared CLT-AgNPs gel was noted (95.6%) in 8 h. It was found that the prepared CLT-AgNPs gel stimulates fibroblast and agranulocytosis development resulting better and timely wound healing.

CONCLUSIONS

The prepared CLT-AgNPs gel can be as a potential substitute in the management and treatment of acute and chronic wounds.

Histomorphometric and CBCT comparison of osseointegration around orthodontic titanium miniscrews coated with different nanoparticles: An in-vivo animal study

BACKGROUND

Temporarily installed titanium orthodontic miniscrews are usually used for many orthodontic applications, especially those cases that need high force, such as skeletally anchored orthodontic appliance cases. Surface modification of titanium miniscrews has proved success in preventing failure and overcoming their limitations.

OBJECTIVE

The present study aims at the assessment of the quality of osseointegration of surface modified titanium miniscrews installed in the maxilla of albino rabbits with cone-beam computed tomography (CBCT) imaging as well as histomorphometric investigations.

MATERIAL AND METHODS

The orthodontic titanium miniscrews (TMSs) were coated with silver/hydroxyapatite (Ag/HA) nanoparticles (NPs) or zinc oxide (ZnO) NPs via electrochemical deposition. The coating nanomaterials were then characterized with X-ray diffractometry (XRD) and scanning electron microscopy (SEM) imaging. Moreover, the antimicrobial activity of the coated titanium miniscrews were evaluated in the rabbits' oral cavity to investigate their ability to prevent biofilm formation.

RESULTS

It was found that the Ag/HA-coated TMSs demonstrated the highest antimicrobial activity and bone area fill, followed by the ZnO NPs-coated TMSs when compared to their uncoated counterparts. In the anterior area surrounding the installed TMSs, the highest osseointegration was demonstrated by ZnO NPs-coated TMSs. However, Ag/HA-coated TMSs showed the highest osseointegration values in the posterior peri-implant area.

CONCLUSIONS

Ag/HA- and ZnO NPs-coated TMSs may provide a promising solution to overcome the 30% probable failure in temporarily installed orthodontic miniscrews, as they can enhance the osseointegration process and prevent biofilm formation.

A review on the chemical and biological sensing applications of silver/carbon dots nanocomposites with their interaction mechanisms

The development of new nanocomposites has a significant impact on modern instrumentation and analytical methods for chemical analysis. Due to their unique properties, carbon dots (CDs) and silver nanoparticles (AgNPs), distinguished by their unique physical, electrochemical, and optical properties, have captivated significant attention. Thus, combining AgNPs and CDs may produce Ag/CDs nanocomposites with improved performances than the individual material. This comprehensive review offers an in-depth exploration of the synthesis, formation mechanism, properties, and the recent surge in chemical and biological sensing applications of Ag/CDs with their sensing mechanisms. Detailed insights into synthesis methods to produce Ag/CDs are unveiled, followed by information on their physicochemical and optical properties. The crux of this review lies in its spotlight on the diverse landscape of chemical and biological sensing applications of Ag/CDs, with a particular focus on fluorescence, electrochemical, colorimetric, surface-enhanced Raman spectroscopy, and surface plasmon resonance sensing techniques. The elucidation of sensing mechanisms of the nanocomposites with various target analytes adds depth to the discussion. Finally, this review culminates with a concise summary and a glimpse into future perspectives of Ag/CDs aiming to achieve highly efficient and enduring Ag/CDs for various applications.

Ultrasonic-assisted synthesis of lignin-based ultrasmall silver nanoparticles for photothermal-mediated sterilization

Lignin-based silver nanoparticles have been considered a promising antimicrobial material. However, it remains challenging to prepare ultra-small size silver nanoparticles sustainably with superior antibacterial performance. In this work, we modified ethanol-extracted lignin (EL) with carboxymethyl groups and further synthesized ultra-small particle size (3.8 ± 0.1 nm) nanosilver incorporated carboxymethyl lignin complexes (AgNPs@CEL) using ultrasonic technology. Due to the outstanding antibacterial properties of the ultra-small size nanosilver, AgNPs@CEL could cause 5.3 and 5.4 log10 CFU/mL reduction against E. coli and S. aureus in 5 min. Meanwhile, AgNPs@CEL exhibited remarkable photothermal antibacterial performance, which caused 6.2 and 6.1 log10 CFU/mL reduction of E. coli and S. aureus, with NIR irradiation for 5 min. Furthermore, the composite films prepared by doping only 0.5 wt% AgNPs@CEL into ethyl cellose could achieve a bactericidal rate more than 99.99 %. This study provides a new insight into design of controlled particle size lignin-based antibacterial nanosilver materials in a sustainable manner and holds promise for applications in antibacterial fields.

Biogenic Salvia species synthesized silver nanoparticles with catalytic, sensing, antimicrobial, and antioxidant properties

Salvia (Lamiaceae family) is used as a brain tonic to improve cognitive function. The species including S. plebeia and S. moorcroftiana are locally used to cure hepatitis, cough, tumours, hemorrhoids, diarrhoea, common cold, flu, and asthma. To the best of authors' knowledge, no previous study has been conducted on synthesis of S. plebeia and S. moorcroftiana silver nanoparticles (SPAgNPs and SMAgNPs). The study was aimed to synthesize AgNPs from the subject species aqueous and ethanol extracts, and assess catalytic potential in degradation of standard and extracted (from yums, candies, and snacks) dyes, nitrophenols, and antibiotics. The study also aimed at AgNPs as probe in sensing metalloids and heavy metal ions including Pb2+, Cu2+, Fe3+, Ni2+, and Zn2+. From the results, it was found that Salvia aqueous extract afforded stable AgNPs in 1:9 and 1:15 (quantity of aqueous extract and silver nitrate solution concentration) whereas ethanol extract yielded AgNPs in 1:10 (quantity of ethanol extract and silver nitrate solution concentration) reacted in sunlight. The size of SPAgNPs and SMAgNPs determined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were 21.7 nm and 19.9 nm, with spherical, cylindrical, and deep hollow morphology. The synthesized AgNPs demonstrated significant potential as catalyst in dyes; Congo red (85 %), methylene blue (75 %), Rhodamine B (<50 %), nitrophenols; ortho-nitrophenol (95-98 %) and para-nitrophenol (95-98 %), dyes extracted from food samples including yums, candies, and snacks. The antibiotics (amoxicillin, doxycycline, levofloxacin) degraded up to 80 %-95 % degradation. Furthermore, the synthesized AgNPs as probe in sensing of Pb2+, Cu2+, and Fe3+ in Kabul river water, due to agglomeration, caused a significant decrease and bathochromic shift of SPR band (430 nm) when analyzed after 30 min. The Pb2+ ions was comparatively more agglomerated and chelated. Thus, the practical applicability of AgNPs in Pb2+ sensing was significant. Based on the results of this research study, the synthesized AgNPs could provide promising efficiency in wastewater treatment containing organic dyes, antibiotics, and heavy metals.

Formulation of silver nanoparticles using Duabanga grandiflora leaf extract and evaluation of their versatile therapeutic applications

The current research focused on the green synthesis of silver nanoparticles (AgNPs) using Duabanga grandiflora leaf extract. The green synthesis of AgNPs was confirmed by the surface plasmon resonance band at 453 nm in a UV-Visible analysis. The formulated AgNPs had a diameter of around 99.72 nm with a spherical shape. Fourier transform infrared (FTIR) spectrum revealed the bio-reducing potential of phytochemicals present in D. grandiflora, which fundamentally influenced the synthesis of AgNPs. Zeta potential, dynamic light scattering (DLS), scanning electron microscopic (SEM), energy-dispersive X-ray spectroscopic (EDX), X-ray diffraction (XRD), and transmission electron microscopic (TEM) analyses were executed to reveal the physicochemical attributes of the AgNPs. The AgNPs were further investigated for their antioxidant, antidiabetic, anticancer, and antibacterial potential. The DPPH free radical assay revealed the potential radical scavenging capacity (IC50 = 76.73 μg/ml) of green synthesized AgNPs. α-Amylase inhibitory assay displayed significant inhibitory potential (IC50 = 162.11 μg/ml) of this starch-breaking enzyme by AgNPs, revealing the antidiabetic potential of AgNPs. AgNPs exhibited potential cytotoxic activity (IC50 = 244.57 µg/ml) against malignant human kidney cells. In addition, AgNPs showed outstanding antibacterial activity against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacterial strains. Interestingly, AgNPs showed cytotoxic and antimicrobial activities at much higher concentrations than radical scavenging and α-amylase inhibitory concentrations. Thus, our finding elaborated the scope of green synthesized AgNPs for diverse therapeutic applications (dose-dependent) for further clinical translation.

Antibacterial applications of biologically synthesized Pichia pastoris silver nanoparticles

Objectives

This article highlights the biological synthesis of silver nanoparticles (AgNPs) with their characteristic analysis, and it focuses on the application of synthesized NPs against multidrug resistance (MDR) bacteria. A cytotoxicity study was performed to assess the biocompatibility.

Methods

Silver nanoparticle (AgNPs) formation was confirmed by different characterization methods such as UV-Vis spectrophotometer, Dynamic light scattering (DLS)- Zeta, Fourier transform infrared (FTIR), and Transmission electron microscope (TEM). The antimicrobial activity of the AgNPs was checked against various bacterial strains of Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Enterococcus faecalis (E. faecalis), and Klebsiella pneumonia (K. pneumonia) by disc diffusion, minimum inhibition concentration test (MIC), and kinetic studies. The cytotoxicity of NPs against the Vero cell line was studied by cytotoxic assay.

Results

The primary analysis of the formation of nanoparticles (NPs) was made by UV-Vis spectrophotometric analysis at 400 nm. At the same time, the efficient capping checked by FTIR shows the presence of a functional group at different wavelengths 3284, 1641,1573,1388,1288, and 1068 cm-1. At the same time, the transmission electron microscopic analysis (TEM) and DLS show that the shape and size of the synthesized NPs possess an average size of around ∼10-30 nm with spherical morphology. Further, the zeta potential confirmed the stability of the NPs. While the yield of NPs formation from silver salt was determined by an online yield calculator with the EDX analysis results. Synthesized NPs showed bactericidal effects against all the selected MDR pathogens with nontoxic effects against mammalian cells.

Conclusion

Our findings indicate the remarkable antimicrobial activity of the biologically synthesized AgNPs, which can be an antimicrobial agent against multi-drug-resistant bacteria.

Silver nanoparticles biogenically synthesised using Maclurodendron porteri extract and their bioactivities

Silver nanoparticle is widely used in various field including medical, cosmetic, food and industrial purposes due to their unique properties in electrical conductivity, thermal, and biological activities. In the medical field, silver nanoparticles (AgNPs) have been reported to have strong antimicrobial and cytotoxic activities. This study aimed to synthesize and characterize silver nanoparticles (AgNPs) using Maclurodendron porteri (MP) extract and to evaluate the antimicrobial and cytotoxic activities of the synthesised MP-AgNPs. Green method of Ultrasound Assisted Extraction (UAE) was used to extract the leaves of M. porter. Liquid Chromatography -Mass Spectrometry/Quadrupole time-of-flight (LC-MS/QTOF) was used to identify the compounds in the leaf extract of M. porteri. Characterisation of the synthesised nanoparticles involved ultraviolet-visible (UV-Vis), Fourier Transform Infrared (FTIR), scanning electromagnetic microscopy (SEM), Zeta potential Analyzer and Particle Size Analyzer. The cytotoxic assay was conducted on MCF-7 and Caco-2 cell lines by MTT assay. Antimicrobial activity was tested on Gram-negative and Gram-positive bacteria using the disc diffusion method. Based on LC-MS/QTOF analysis, 430 compounds were found. The identified major compounds consist of amino acids, polyphenols, steroids, terpenoids and heterocyclic compounds which possibly act as reducing agents. 1 mM, 5 mM and 10 mM of silver nitrate solution were mixed with the leaf extract to form silver nanoparticles. 1.2 mg/ml of MP-AgNPs were found to have antibacterial activity against B. subtilis, S. aureus, E. coli, and P. aeruginosa with inhibitory zones of 8.0 ± 0.36 mm, 8.5 ± 0.45 mm, 7.5 ± 0.36 mm, and 9.0 ± 0.40 mm respectively. MP-AgNPs showed no cytotoxic activity against Caco-2 and MCF-7 cells. In conclusion, the presence of major amine compounds such as 10,11-dihydro-10,11-dihydroxyprotriptyline and harderoporphyrin in the extract facilitated the synthesis of AgNPs and the nanoparticle showed weak bioactivities in the assay conducted.

Investigating the synthesis parameters of durian skin-based activated carbon and the effects of silver nanocatalysts on its recyclability in methylene blue removal

Activated carbon (AC) is the most common and economically viable adsorbent for eliminating toxic organic pollutants, particularly dyes, from wastewater. Its widespread adoption is due to the simplicity and affordable production of AC, wherein low-cost agricultural wastes, such as durian skin can be used. Converting durian skin into AC presents a promising solution for its solid waste management. However, inherent drawbacks such as its non-selectivity, relatively short lifespan and laborious replacement and recovery processes diminish the overall efficacy of AC as an adsorbent. To address these challenges, the immobilisation of metal nanocatalysts such as silver nanoparticles (AgNPs) is one of the emerging solutions. AgNPs can facilitate the regeneration of the adsorption sites of AC by catalysing the conversion of the adsorbed dyes into harmless and simpler molecules. Nevertheless, the immobilisation of AgNPs on AC surface can be challenging as the pore size formation of AC is hard to control and the nanomaterials can easily leach out from the AC surface. Hence, in this study, we synthesised AC from durian skin (DS) and immobilised AgNPs on the AC-DS surface. Then, we used methylene blue (MB) removal for studying the adsorption capability and recyclability of the AC-DS. In the synthesis of AC-DS, the influences of reaction temperature, activating agent, and acid-washing to its capability in adsorptive removal of  MB in solution were first determined. It was found that 400 °C, KOH activating agent, and the presence of acid-washing (50% of HNO3) resulted in AC-DS with the highest percentage of MB removal (91.49 ± 2.86%). Then, the overall results from three recyclability experiments demonstrate that AC-DS with immobilised AgNPs exhibited higher MB removal after several cycles (up to 6 cycles) as compared to AC-DS alone, proving the benefit of AgNPs for the recyclability of AC-DS. We also found that AgNPs/Citrate@AC-DS exhibited better adsorption capability and recyclability as compared to AgNPs/PVP@AC-DS indicating significant influences of type of stabilisers in this study. This study also demonstrates that the presence of more oxygen-containing functional groups (i.e., carboxyl and hydroxyl functional groups) after acid-washing on AC-DS and in citrate molecules, has greater influence to the performance of AC-DS and AgNPs/Citrate@AC-DS in the removal of MB as compared to the influences of their BET surface area and pore structure. The findings in this study have the potential to promote and serve as a guideline for harnessing the advantages of nanomaterials, such as AgNPs, to enhance the properties of AC for environmental applications.

Multifaceted Applications of DNA-Capped Silver Nanoparticles in Photonics, Photocatalysis, Antibacterial Activity, Cytotoxicity, and Bioimaging

Deoxyribonucleic acid (DNA) capped silver nanoparticles are exceptional nanomaterials, featuring precise size and shape control enabled by DNA as a capping agent. DNA stabilizes these nanoparticles' role leading to uniform structures for diverse applications. These nanoparticles are excellent in photonics and medical applications, enhancing fluorescence and medical imaging. In this study, we explore the multifaceted applications of DNA-capped silver nanoparticles, delving into their optical, photocatalytic, antibacterial, cytotoxic, and bioimaging properties. Employing UV-visible absorption spectroscopy and scanning electron microscopy, we provide an analysis of confirmation of silver nanoparticles. The investigation demonstrates substantial photocatalytic efficacy, photodegradation of methylene blue is higher than rhodamine 6G. The presence of silver nanoparticles enhances the fluorescence of rhodamine 6G doped sol-gel glasses. Furthermore, our findings illustrate significant antibacterial effects, encompassing both Gram-positive and Gram-negative bacteria, with DNA-capped silver nanoparticles exhibiting antibacterial activity. Cytotoxicity assessments on HeLa cells reveal concentration-dependent effects, with an LC50 value of 47 µL. Additionally, the in vitro experiments with HeLa cells suggest the promising utility of DNA-capped silver nanoparticles for bioimaging applications. This comprehensive analysis highlights the multifunctionality and potential of DNA-capped silver nanoparticles, offering promising avenues for further exploration and innovation within various scientific domains, particularly in the realm of nanomaterial research.

Unveiling the inhibition of chlortetracycline photodegradation and the increase of toxicity when coexisting with silver nanoparticles

Silver nanoparticles (AgNPs) and antibiotics inevitably co-exist in water environment. Nonetheless, little is known regarding the interactions between AgNPs and antibiotics or the effects of AgNPs on environmental behavior of antibiotics, particularly on sunlight-driven transformation. In the present work, we found that AgNPs obviously inhibit the photochemical decay of chlortetracycline (CTC), and CTC boosts the dissolution of AgNPs. With the help of electron paramagnetic resonance (EPR) and quenching experiment, we ascertained that these results originated from the competition between AgNPs against CTC for capturing 1O2 generated from CTC photosensitization. 1O2 reacting with CTC contributed mostly to CTC photodegradation, while 1O2 as well reacting with AgNPs leads to release of Ag+. When compared to reaction of 1O2 with CTC, 1O2 is prone to react with AgNPs, based on lower Gibbs free energy of AgNPs reacting with 1O2. Therefore, upon CTC co-existing with AgNPs, the release of Ag+ was accelerated and the photodegradation of CTC was inhibited obviously. Furthermore, the accelerated release of Ag+ significantly increased their toxicity toward E. coli cells under simulate sunlight irradiation. Overall, the findings demonstrate how AgNPs interact with CTC and how these interactions affect the environmental behaviors of CTC or AgNPs, allowing more accurate assessments of the risk to ecosystems posed by AgNPs coexisting with antibiotics.

Review on fate, transport, toxicity and health risk of nanoparticles in natural ecosystems: Emerging challenges in the modern age and solutions toward a sustainable environment

In today's era, nanoparticles (NPs) have become an integral part of human life, finding extensive applications in various fields of science, pharmacy, medicine, industry, electronics, and communication. The increasing popularity of NP usage worldwide is a testament to their tremendous potential. However, the widespread deployment of NPs unavoidably leads to their release into the environmental matrices, resulting in persistence in ecosystems and bioaccumulation in organisms. Understanding the environmental behavior of NPs poses a significant challenge due to their nanoscale size. Given the current environmental releases of NPs, known negative consequences, and the limited knowledge available for risk management, comprehending the toxicity of NPs in ecosystems is both awaiting and crucial. The present review aims to unravel the potential environmental influences of nano-scaled materials, and provides in-depth inferences of the current knowledge and understanding in this field. The review comprehensively summarizes the sources, fate, transport, toxicity, health risks, and remediation solutions associated with NP pollution in aquatic and soil ecosystems. Furthermore, it addresses the knowledge gaps and outlines further investigation priorities for the sustainable control of NP pollution in these environments. By gaining a holistic understanding of these aspects, we can work toward ensuring the responsible and sustainable use of NPs in today's fast-growing world.

An intrusion and environmental effects of man-made silver nanoparticles in cold seeps

Silver nanoparticles (AgNPs) are among the most widely used metal-based engineered nanomaterials in biomedicine and nanotechnology, and account for >50 % of global nanomaterial consumer products. The increasing use of AgNPs potentially causes marine ecosystem changes; however, the environmental impacts of man-made AgNPs are still poorly studied. This study reports for the first time that man-made AgNPs intruded into cold seeps, which are important marine ecosystems where hydrogen sulfide, methane, and other hydrocarbon-rich fluid seepage occur. Using a combination of electron microscopy, geochemical and metagenomic analyses, we found that in the cold seeps with high AgNPs concentrations, the relative abundance of genes associated with anaerobic oxidation of methane (AOM) was lower, while those related to the sulfide oxidizing and sulfate reducing were higher. This suggests that AgNPs can stimulate the proliferation of sulfate-reducing and sulfide-oxidizing bacteria, likely due to the effects of activating repair mechanisms of the cells against the toxicant. A reaction of AgNPs with hydrogen sulfide to form silver sulfide could also effectively reduce the amount of available sulfate in local ecosystems, which is generally used as the AOM oxidant. These novel findings indicate that man-made AgNPs may be involved in the biogeochemical cycles of sulfur and carbon in nature, and their potential effects on the releasing of methane from the marine methane seeps should not be ignored in both scientific and environmental aspects.

Photosensitive Hydrogels Encapsulating DPSCs and AgNPs for Dental Pulp Regeneration

OBJECTIVE

Pulp regeneration with bioactive dentin-pulp complex has been a research hotspot in recent years. Stem cell therapy provided an interest strategy to regenerate the dental-pulp complex. Hence, this study aimed to evaluate the effects of photosensitive gelatin methacrylate (GelMA) hydrogel encapsulating dental pulp stem cells (DPSCs) and silver nanoparticles (AgNPs) for dental pulp regeneration in vitro.

METHODS

First, the AgNPs@GelMA hydrogels were prepared by lithium phenyl-2,4,6-trimethyl-benzoyl phosphinate (LAP) initiation via blue-light emitting diode light. The physical and chemical properties of AgNPs@GelMA hydrogels were comprehensively analysed via scanning electron microscopy (SEM), and mechanical characterisation, such as swelling ability, degradation properties, and AgNP release profile. Then, AgNPs@GelMA hydrogels encapsulated DPSCs were used to establish an AgNPs@GelMA biomimetic complex, further analysing its biocompatibility, antibacterial properties, and angiogenic capacity in vitro.

RESULTS

The results indicated that GelMA hydrogels demontrated optimal characteristics with a monomer:LAP ratio of 16:1. The physico-chemical properties of AgNPs@GelMA hydrogels did not change significantly after loading with AgNPs. There was no significant difference in AgNP release rate amongst different concentrations of AgNPs@GelMA hydrogels. Fifty to 200 μg/mL AgNPs@GelMA hydrogels could disperse E faecalis biofilm and reduce its metabolic activity . Furthermore, cell proliferation was arrested in 100 and 200 μg/mL AgNPs@GelMA hydrogels. The inhibition of 50 μg/mL AgNPs@GelMA hydrogels on E faecalis biofilm was above 50%, and the cell viability of the hydrogels was higher than 90%. The angiogenesis assay indicated that AgNPs@GelMA hydrogels encapsulating DPSCs could induce the formation of capillary-like structures and express angiogenic markers CD31, vascular endothelial growth factor , and von willebrand factor (vWF) in vitro.

CONCLUSIONS

Results of this study indicate that 50 μg/mL AgNPs@GelMA hydrogels encapsulating DPSCs had significant antibacterial properties and angiogenic capacity, which could provide a significant experimental basis for the regeneration of the dentin-pulp complex.

Silver nanoparticle functionalized by glutamine and conjugated with thiosemicarbazide induces apoptosis in colon cancer cell line

The high mortality rate of colon cancer indicates the insufficient efficacy of current chemotherapy. Thus, the discussion on engineered metal nanoparticles in the treatment of the disease has been considered. In this study, silver nanoparticles were functionalized with glutamine and conjugated with thiosemiccarbazide. Then, anticancer mechanism of Ag@Gln-TSC NPs in a colon cancer cell line (SW480) was investigated. Characterizing Ag@Gln-TSC NPs by FT-IR, XRD, EDS-mapping, DLS, zeta potential, and SEM and TEM microscopy revealed that the Ag@Gln-TSC NPs were correctly synthesized, the particles were spherical, with surface charge of - 27.3 mV, high thermal stability and low agglomeration level. Using MTT assay we found that Ag@Gln-TSC NPs were significantly more toxic for colon cancer cells than normal fibroblast cells with IC50 of 88 and 186 µg/mL, respectively. Flow cytometry analysis showed that treating colon cancer cells with Ag@Gln-TSC NPs leads to a considerable increase in the frequency of apoptotic cells (85.9% of the cells) and increased cell cycle arrest at the S phase. Also, several apoptotic features, including hyperactivity of caspase-3 (5.15 folds), increased expression of CASP8 gene (3.8 folds), and apoptotic nuclear alterations were noticed in the nanoparticle treated cells. Furthermore, treating colon cancer cells with Ag@Gln-TSC NPs caused significant down-regulation of the HULC Lnc-RNA and PPFIA4 oncogene by 0.3 and 0.6 folds, respectively. Overall, this work showed that Ag@Gln-TSC NPs can effectively inhibit colon cancer cells through the activation of apoptotic pathways, a feature that can be considered more in studies in the field of colon cancer treatment.

Smart optical sensing of multiple antibiotic residues from wastewater effluents with ensured specificity using SERS assisted with multivariate analysis

Surface-enhanced Raman spectroscopy offers great potential for rapid and highly sensitive detection of pharmaceuticals from environmental sources. Herein, we investigated the feasibility of label-free sensing of antibiotic residues from wastewater effluents with high specificity by combining with multivariate analysis. Highly ordered silver nanoarrays with ∼34 nm roughness have been fabricated using a cost-effective electroless deposition technique. As-fabricated Ag arrays showed superior LSPR effects with an enhancement factor of 8 × 107. Excellent reproducibility has also been noticed with RSD values within 11%, whilst the sensor showed good stability and reusability characteristics for being used as a low-cost and reusable sensor. SERS studies demonstrated that antibiotics-spiked wastewater effluents can be detected with high efficiency in a label-free method. The molecular fingerprint bands of antibiotics such as sulfamethoxazole, sulfadiazine, and ciprofloxacin were well analyzed in effluent, tap, and deionized water. It has been found that antibiotics can be detected near picomolar levels; meanwhile, liquid chromatography-mass spectrometry (LC-MS) exhibited a detection limit within nanomolar concentrations only. Furthermore, the specificity of SERS sensing has been further analyzed using a multivariate analysis method, principal component analysis followed by linear discriminant analysis (PCA-LDA); which showed prominent discrimination to distinguish each antibiotic residue from wastewater effluents. The current study presented the potential of Ag nanoarray sensors for rapid, highly specific, and cost-effective analysis of pharmaceutical products for environmental remediation applications.

Biosynthesis of silver nanoparticles by banana pulp extract: Characterizations, antibacterial activity, and bioelectricity generation

Here, green banana pulp extract (PE) has been used as a bio-reducing agent for the reduction of silver ions to silver nanoparticles (AgNPs). Bio-synthesized AgNPs were characterized by using UV, XRD, FEEM, TEM, and FTIR analysis. The face-centered cubic structures of AgNPs were formed with an average crystallite size of 31.26 nm and an average particle size of 42.97 nm. In this report, the electrical activities of green synthesized AgNPs have been evaluated along with the antibacterial activities. The antibacterial activities of AgNPs were evaluated against two pathogenic bacteria: Escherichia coli (gram-negative) and Staphylococcus epidermidis (gram-positive). AgNPs were added to the electrochemical cell and results demonstrated the improvement of power of the electrochemical cell. Green synthesized AgNPs showed excellent antibacterial activities against both gram-positive and negative bacteria and most importantly the NPs played an important role as an effective catalyst to enhance the electrical performance of bio-electrochemical cells. These significant findings may help in the advancement of nanotechnology in biomedical applications as well as in the creation of cheap and eco-friendly power generation devices.

Green-synthesized silver nanoparticles from Zingiber officinale extract: antioxidant potential, biocompatibility, anti-LOX properties, and in silico analysis

INTRODUCTION

Zingiber officinale extract has emerged as a compelling candidate for green synthesis of nanoparticles, offering diverse applications across medicine, cosmetics, and nutrition. This study delves into the investigation of in vitro toxicity and explores the biomedical utility of green-synthesized silver nanoparticles derived from ginger extract (GE-AgNPs).

METHODS

We employed established protocols to evaluate in vitro aspects such as antioxidant capacity, anti-inflammatory potential, and biocompatibility of GE-AgNPs. Additionally, molecular docking was employed to assess their anti-lipoxygenase (anti-LOX) activity.

RESULTS

Our findings highlight that the extraction of ginger extract at a pH of 6, utilizing a cosolvent blend of ethanol and ethyl acetate in a 1:1 ratio, yields heightened antioxidant capacity attributed to its rich phenolic and flavonoid content. In the context of silver nanoparticle synthesis, pH 6 extraction yields the highest quantity of nanoparticles, characterized by an average size of 32.64 ± 1.65 nm. Of particular significance, GE-AgNPs (at pH 6) demonstrated remarkable efficacy in scavenging free radicals, as evidenced by an IC50 value of 6.83 ± 0.47 µg/mL. The results from the anti-LOX experiment indicate that GE-AgNPs, at a concentration of 10 µg/mL, can inhibit LOX activity by 25%, outperforming ginger extract which inhibits LOX by 17-18%. Notably, clionasterol exhibited higher binding energy and enhanced stability (-8.9 kcal/mol) compared to nordihydroguaiaretic acid. Furthermore, a cell viability study confirmed the safety of GE-AgNPs at a concentration of 17.52 ± 7.00 µg/mL against the L929 cell line.

CONCLUSION

These comprehensive findings underscore the significant biomedical advantages of GE-AgNPs and emphasize their potential incorporation into cosmetic products at a maximum concentration of 10 µg/mL.

Assessing cytotoxicity and endoplasmic reticulum stress in human blood-brain barrier cells due to silver and copper oxide nanoparticles

In recent years, it has been generally accepted that metal-based nanoparticles (NPs) may induce stress in the endoplasmic reticulum (ER), a key organelle where protein folding occurs. We examined ER stress in immortalized human cerebral microvascular cells (hCMEC/D3) after exposure to silver-NPs (Ag-NPs)- and copper oxide-NPs (CuO-NPs) induced toxicity at < 10 nm and < 40 nm or < 50 nm diameters, respectively. In cytotoxicity assessments, cells were exposed to different CuO-NPs (5-400 µg/mL) or Ag-NPs (1-10 µg/mL) concentration ranges for 24 h and 72 h, and tetrazole salt reduction assays (EZ4U) were performed. Also, Ag-NP or CuO-NP effects on cell proliferation, apoptosis (caspase 3/7 assays), and ER stress and cell morphology were evaluated. In ER stress assessments, RNA-like endoplasmic reticulum kinase (PERK), activating transcription factor 6 (ATF6), inositol-requiring enzyme 1 (IRE1a), and others stress factor mRNA levels were determined after 24 h treatment using Real-Time PCR. Increased stress sensors (IRE1a, PERK, and ATF6) mRNA levels were observed after exposure to Ag-NPs (< 10 and < 40 nm) or CuO-NPs (< 50 nm). We investigated the expression of tight junction (TJ) proteins (barrier junctions) and showed that both types of NP reduced of OCLN gene expression. Morphological changes were observed after Ag-NP or CuO-NP exposure using holotomographic microscopy. Our data suggest that Ag- and CuO-NPs should undergo future in vitro and in vivo toxicology studies, especially for downstream biomedical application and occupational risk assessments.

Antibacterial, antibiofilm, and anticancer activity of silver-nanoparticles synthesized from the cell-filtrate of Streptomyces enissocaesilis

Silver nanoparticles (Ag-NPs) have a unique mode of action as antibacterial agents in addition to their anticancer and antioxidant properties. In this study, microbial nanotechnology is employed to synthesize Ag-NPs using the cell filtrate of Streptomyces enissocaesilis BS1. The synthesized Ag-NPs are confirmed by ultraviolet-visible (UV-Vis), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Also, the effects of different factors on Ag-NPs synthesis were evaluated to set the optimum synthesis conditions. Also, the antibacterial, antibiofilm, and anticancer activity of Ag-NPs was assessed. The X-ray diffraction (XRD) analysis confirmed the crystalline nature of the sample and validated that the crystal structure under consideration is a face-centered cubic (FCC) pattern. The TEM examination displayed the spherical particles of the Ag-NPs and their average size, which is 32.2 nm. Fourier transform infrared spectroscopy (FTIR) revealed significant changes in functionality after silver nanoparticle dispersion, which could be attributed to the potency of the cell filtrate of Streptomyces enissocaesilis BS1 to act as both a reducing agent and a capping agent. The bioactivity tests showed that our synthesized Ag-NPs exhibited remarkable antibacterial activity against different pathogenic strains. Also, when the preformed biofilms of Pseudomonas aeruginosa ATCC 9027, Salmonella typhi ATCC 12023, Escherichia coli ATCC 8739, and Staphylococcus aureus ATCC 6598 were exposed to Ag NPs 50 mg/ml for 24 hours, the biofilm biomass was reduced by 10.7, 34.6, 34.75, and 39.08%, respectively. Furthermore, the Ag-NPs showed in vitro cancer-specific sensitivity against human breast cancer MCF-7 cell lines and colon cancer cell line Caco-2, and the IC50 was 0.160 mg/mL and 0.156 mg/mL, respectively. The results of this study prove the ease and efficiency of the synthesis of Ag-NPs using actinomycetes and demonstrate the significant potential of these Ag-NPs as anticancer and antibacterial agents.

The biochemical and growth-associated traits of basil (Ocimum basilicum L.) affected by silver nanoparticles and silver

BACKGROUND

The biochemical and growth changes resulting from exposure of basil (Ocimum basilicum L.) seedlings to silver nanoparticles and silver were investigated. Over a two-week period, seedlings were exposed to different concentrations (0, 40, and 80 ppm) of silver nanoparticles and silver.

RESULTS

Our findings revealed that at concentrations of 40 and 80 ppm, both silver nanoparticles and silver nitrate led to decreased weight, root and shoot length, as well as chlorophyll a and b content. Conversely, these treatments triggered an increase in key biochemical properties, such as total phenols, carotenoids and anthocyanins, with silver nanoparticles showing a more pronounced effect compared to silver nitrate. Moreover, the levels of malondialdehyde (MDA) and hydrogen peroxide (H2O2) rose proportionally with treatment concentration, with the nanoparticle treatment exhibiting a more substantial increase. Silver content showed a significant upswing in both roots and leaves as treatment concentrations increased.

CONCLUSIONS

Application of varying concentrations of silver nanoparticles and silver nitrate on basil plants resulted in reduced growth and lower chlorophyll content, while simultaneously boosting the production of antioxidant compounds. Notably, anthocyanin, carotenoid, and total phenol increased significantly. However, despite this increase in antioxidant activity, the plant remained unable to fully mitigate the oxidative stress induced by silver and silver nanoparticles.

Flexible, foldable and transparent SERS film with high sensitivity and signal homogeneity via silver ion exchange and in-situ reduction

The adhesion between metal plasma and substrate was the key of surface-enhanced Raman scattering (SERS) technology. The preparation of ideal SERS substrate with multiple advantages such as high sensitivity and good signal reproducibility was still the focus of research. A flexible foldable and transparent fluorinated polyimide/silver NPs (FPI@Ag) SERS film was fabricated by the ion exchange and in-situ reduction method in this work. The effects of KOH hydrolysis time, AgNO3 ion exchange time and concentration, the type and concentration of reducing agents on the SERS performance of the FPI@Ag film were systematically discussed. As a result, the hydrolysis time of KOH affected the thickness of the metallic silver layer, the concentration of AgNO3 affected the size and spacing of Ag NPs, and the Raman signal of was remarkably enhanced when borane dimethylamine complex (DMAB) was used as reducing agent. When the detection limit of 4-Aminothiophenol was as low as 1 × 10-11 mol·L-1, the obvious Raman characteristic peak still appeared. The enhancement factor (EF) was up to 9.4 × 107. The linear quantification range was achieved in the range from 10-3-10-11 mol·L-1, R2 = 0.9987. In addition, we also performed multi-cycle bending and torsion test on the FPI@Ag film, and obtained stable Raman signals. The prepared FPI@Ag film can be attached to the surface of uneven samples, which can be used for on-site Raman detection and analysis.

Construction of durable antibacterial cellulose textiles through grafting dynamic disulfide-containing amino-compound and nanosilver deposition

Cotton textile is very comfortable to wear, and also provides an ideal environment for bacterial propagation, easily causing harm to human health. In order to address this issue, various antibacterial techniques are employed for cotton finishing. However, some processes are complex and involve the use of environmentally unfriendly chemicals. In this work, a durable and efficient antibacterial cotton fabric was prepared via grafting of an amino-compound containing dynamic disulfide bonds, and then in-situ deposition of silver nanoparticles (AgNPs). Briefly, the reactive α-lipoic acid-modified polyethyleneimine (mPEI) was introduced to the cotton fibers via thiol-ene click reaction. Subsequently, the amino groups and dynamically-generated sulfhydryl groups in the mPEI molecules were used to initiate the ultrafast reduction of silver ions without the participation of additional reductant, constructing a stable antibacterial layer on fiber surface. The results reveal that the amino and thiol groups of mPEI could form coordination bonds with the deposited silver nanoparticles, and the antibacterial ability of AgNP@cotton-g-mPEI fabric remains at a high level even after 20 washing cycles. After 30 min of contact with Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), the antibacterial rates against both bacteria reached 99.99 %. Meanwhile, the network matrix constructed by the recombination of the dynamic disulfide bonds in mPEI endows the cotton fabric with detectable wrinkle resistance and encouraging anti-ultraviolet effect. The present work provides a novel alternative for preparation of durable and efficient antibacterial textiles.

Silver nanoparticles induce endothelial cytotoxicity through ROS-mediated mitochondria-lysosome damage and autophagy perturbation: The protective role of N-acetylcysteine

Silver nanoparticles (AgNPs) are used increasingly often in the biomedical field, but their potential deleterious effects on the cardiovascular system remain to be elucidated. The primary aim of this study was to evaluate the toxic effects, and the underlying mechanisms of these effects, of AgNPs on human umbilical vein endothelial cells (HUVECs), as well as the protective role of N-acetylcysteine (NAC) against cytotoxicity induced by AgNPs. In this study, we found that exposure to AgNPs affects the morphology and function of endothelial cells which manifests as decreased cell proliferation, migration, and angiogenesis ability. Mechanistically, AgNPs can induce excessive cellular production of reactive oxygen species (ROS), leading to damage to cellular sub-organs such as mitochondria and lysosomes. More importantly, our data suggest that AgNPs causes autophagy defect, inhibits mitophagy, and finally activates the mitochondria-mediated apoptosis signaling pathway and evokes cell death. Interestingly, treatment with ROS scavenger-NAC can effectively suppress AgNP-induced endothelial damage.Our results indicate that ROS-mediated mitochondria-lysosome injury and autophagy dysfunction are potential factors of endothelial toxicity induced by AgNPs. This study may provide new evidence for the cardiovascular toxicity of AgNPs and serve as a reference for the safe use of nanoparticles(NPs) in the future.

Bioinspired multiscale cellulose/lignin-silver composite films with robust mechanical, antioxidant and antibacterial properties for ultraviolet shielding

Constructing a high-performance ultraviolet shielding film is an effective way for addressing the growing problem of ultraviolet radiation. However, it is still a great challenge to achieve a combination of multifunctional, excellent mechanical properties and low cost. Here, inspired by the multiscale structure of biomaterials and features of lignin, a multifunctional composite film (CNF/CMF/Lig-Ag) is constructed via a facile vacuum-filtration method by introducing micron-sized cellulose fibers (CMF) and lignin-silver nanoparticles (Lig-Ag NPs) into the cellulose nanofibers (CNF) film network. In this composite film, the microfibers interweave with nanofibers to form a multiscale three-dimensional network, which ensures satisfactory mechanical properties of the composite film. Meanwhile, the Lig-Ag NPs are employed as a multifunctional filler to enhance the composite film's antioxidant, antibacterial and ultraviolet shielding abilities. As a result, the prepared CNF/CMF/Lig-Ag composite film demonstrates excellent mechanical properties (with tensile strength of 133.8 MPa and fracture strain of 7.4 %), good biocompatibility, high thermal stability, potent antioxidant and antibacterial properties. More importantly, such composite film achieves a high ultraviolet shielding rate of 98.2 % for ultraviolet radiation A (UVA) and 99.4 % for ultraviolet radiation B (UVB), respectively. Therefore, the prepared CNF/CMF/Lig-Ag composite film shows great potential in application of ultraviolet protection.

Chitosan-based topical formulation integrated with green-synthesized silver nanoparticles utilizing Camellia sinensis leaf extracts: A promising approach for managing infected wounds

This study explores the eco-friendly biosynthesis of silver nanoparticles (AgNPs) utilizing Camellia sinensis leaf extract. We assess their antioxidant and antibacterial properties. Furthermore, we impregnated AgNPs into 2 % chitosan (CHS) gel and assessed their wound-healing potential in Escherichia coli and Staphylococcus aureus infected wounds. Optimized AgNPs demonstrated a mean particle size of 36.90 ± 1.22 nm and a PDI of 0.049 ± 0.001. Green-synthesized AgNPs exhibited enhanced free radical inhibition (IC50: 31.45 μg/mL, 34.01 μg/mL, 27.40 μg/mL) compared to leaf extract (IC50: 52.67 μg/mL, 59.64 μg/mL, 97.50 μg/mL) in DPPH, hydrogen peroxide, and nitric oxide free radical scavenging assays, respectively. The MIC/MBC values of AgNPs against E. coli and S. aureus were 5 ppm/ 7.5 ppm and 10 ppm/ 15 ppm, respectively. Furthermore, our study showed that green-synthesized AgNPs at MIC significantly reduced the biofilm production of E. coli (70.37 %) and S. aureus (67.40 %). The CHS/AgNPs gel exhibited potent wound healing activities, comparable to a commercial cream with the re-epithelialization period of 8.16 ± 0.75. Histological analysis demonstrated enhanced skin regeneration with a thicker epidermal layer, well-defined papillary dermal structure, and organized collagen fibers. In summary, these findings hold promise for addressing bacterial infections, particularly those associated with biofilms-related wound infections.

Sustainable organosolv-lignin coated nanosilver-halloysites reinforced poly (vinyl alcohol) nanocomposites for wound healing application

This study involves the fabrication of innovative poly (vinyl alcohol) nanocomposite films by incorporating silver-embedded clay nanotubes with organosolv-lignin by the solution casting approach. The confirmation of this procedure was achieved through the utilisation of many techniques, including FTIR, PXRD, FE-SEM, and TGA. The aforementioned research have verified the adherence of silver nanoparticles to the surface of raw halloysites. The confirmation of lignin functionalization on these nanotubes has been established. This novel nanofiller was used to make a range of nanocomposite films with varying weight percentages ranging from 0 wt% to 5 wt%. With the increase in the wt% of nanofillers, These nanocomposite films exhibited greater thermal and mechanical stability compared to plain PVA. An investigation was conducted to examine the impact of the films on the cellular behaviour of murine fibroblast (NIH3T3) cell lines. Based on the findings from cell proliferation and scratch testing, it has been determined that these nanocomposite films are not harmful to cells, exhibit a greater rate of cell multiplication (116 ± 1.19), and demonstrate increased migratory capabilities (86.5 ± 0.50). Further investigations of human blood corroborate the evidence that these films are compatible with blood. Nanocomposite films have the potential to serve as wound healers following pre-clinical and clinical testing.

Green synthesis of silver nanoparticles from discarded shells of velvet tamarind (Dialium cochinchinense) and their antimicrobial synergistic potentials and biofilm inhibition properties

In the field of nanomedicine, biogenic metal nanoparticles are commonly synthesized using edible plant products as bio-reducing or stabilizing agents. In this study, discarded shell of velvet tamarind fruit is explored as a potent reducing agent for biogenic synthesis of silver nanoparticles (VeV-AgNPs). Silver nanoparticles were formed in minutes under sunlight exposure, which was considerably fast compared to under ambient conditions. The optical, structural and morphological studies revealed that the nanoparticle colloidal solution consisted of particles with quasi-spherical and rodlike morphologies. To investigate antimicrobial properties, eight microorganisms were exposed to the VeV-AgNPs. The results indicated that VeV-AgNPs had enhanced antimicrobial activity, with a recorded minimum inhibitory concentration (MIC) of 3.9 µg/mL against E. coli. Further studies were conducted to examine the biofilm inhibition properties and synergistic effect of the VeV-AgNPs. The findings showed a biofilm inhibition potential of around 98% against E. coli, and the particles were also found to increase the efficacy of standard antimicrobial agents. The combinatory effect with standard antifungal and antibacterial agents ranged from synergistic to antagonistic effects against the tested microorganisms. These results suggest that silver nanoparticles produced from discarded shells of velvet tamarind are potent and could be used as a potential drug candidate to combat antimicrobial resistance.

Valorization of plant by-products in the biosynthesis of silver nanoparticles with antimicrobial and catalytic properties

Biosynthesis based on natural compounds has emerged as a sustainable approach for the production of metallic nanoparticles (MNP). The main objective of this study was to biosynthesize stable and multifunctional silver nanoparticles (AgNP) using different plant by-products as reducers and capping agents. Extracts obtained from Eucalyptus globulus, Pinus pinaster, Citrus sinensis, Cedrus atlantica and Camellia sinensis by-products, were evaluated. From all plant by-products tested, aqueous extract of eucalyptus leaves (EL), green tea (GT) and black tea (BT) were selected due to their higher antioxidant phenolic content and were individually employed as reducers and capping agents to biosynthesize AgNP. The green AgNP showed zeta potential values of -31.8 to -36.3 mV, with a wide range of particle sizes (40.6 to 86.4 nm), depending on the plant extract used. Green AgNP exhibited an inhibitory effect against various pathogenic bacteria, including Gram-negative (P. putida, E. coli, Vibrio spp.) and Gram-positive (B. megaterium, S. aureus, S. equisimilis) bacteria with EL-AgNP being the nanostructure with the greatest antimicrobial action. EL-AgNP showed an excellent photodegradation of indigo carmine (IC) dye under direct sunlight, with a removal percentage of up to 100% after 75 min. A complete cost analysis revealed a competitive total cost range of 8.0-9.0 €/g for the biosynthesis of AgNP.

Silver nanoparticle ecotoxicity and phytoremediation: a critical review of current research and future prospects

Silver nanoparticles (AgNPs) are widely used in various industries, including textiles, electronics, and biomedical fields, due to their unique optical, electronic, and antimicrobial properties. However, the extensive use of AgNPs has raised concerns about their potential ecotoxicity and adverse effects on the environment. AgNPs can enter the environment through different pathways, such as wastewater, surface runoff, and soil application and can interact with living organisms through adsorption, ingestion, and accumulation, causing toxicity and harm. The small size, high surface area-to-volume ratio, and ability to generate reactive oxygen species (ROS) make AgNPs particularly toxic. Various bioremediation strategies, such as phytoremediation, have been proposed to mitigate the toxic effects of AgNPs and minimize their impact on the environment. Further research is needed to improve these strategies and ensure their safety and efficacy in different environmental settings.

Formulation optimization and evaluation of oromucosal in situ gel loaded with silver nanoparticles prepared by green biosynthesis

Treating oral diseases remains challenging as API is quickly washed out of the application site by saliva turnover and mouth movements. In situ gels are a class of application forms that present sol-gel transition's ability as a response to stimuli. Their tunable properties are provided using smart polymers responsible for stimuli sensitivity, often providing mucoadhesivity. In this study, antimicrobial in situ gels of thermosensitive and pH-sensitive polymers loaded with silver nanoparticles were prepared and evaluated. The nanoparticles were prepared by green synthesis using Agrimonia eupatoria L. extract. According to the data analysis, the in situ gel with the most promising profile contained 15 % of Pluronic® F-127, 0.25 % of methylcellulose, and 0.1 % of Noveon® AA-1. Pluronic® F-127 and methylcellulose significantly increased the viscosity of in situ gels at 37 °C and shear rates similar to speaking and swallowing. At 20 °C, a behavior close to a Newtonian fluid was observed while being easily injectable (injection force 13.455 ± 1.973 N). The viscosity of the formulation increased with temperature and reached 2962.77 ± 63.37 mPa·s (37 °C). A temperature increase led to increased adhesiveness and rigidity of the formulation. The critical sol-gel transition temperature at physiological pH was 32.65 ± 0.35 °C. 96.77 ± 3.26 % of Ag NPs were released by erosion and dissolution of the gel after 40 min. The determination of MIC showed effect against E. coli and S. aureus (0.0625 mM and 0.5000 mM, respectively). The relative inhibition zone diameter of the in situ gel was 73.32 ± 11.06 % compared to gentamicin sulfate. This work discusses the optimization of the formulation of novel antibacterial in situ gel for oromucosal delivery, analyses the impact of the concentration of excipients on the dependent variables, and suggests appropriate evaluation of the formulation in terms of its indication. This study offers a promising dosage form for local treatment of oral diseases.

Synergistic effects of nano curcumin mediated photodynamic inactivation and nano-silver@colistin against Pseudomonas aeruginosa biofilms

BACKGROUND

Patients with burn injuries colonized by multidrug-resistant Pseudomonas aeruginosa face increased mortality risk. The efficacy of colistin, a last-resort treatment, is declining as resistance levels rise. P. aeruginosa's robust biofilm exacerbates antibiotic resistance. Photodynamic Inactivation (PDI) shows promise in fighting biofilm.

MATERIALS AND METHODS

Nano curcumin (nCur) particles were synthesized, and their chemical characteristics were determined using zeta potential (ZP), dynamic light scattering analysis (DLS), energy-dispersive X-ray (EDX) analysis, and fourier transform infrared (FTIR). We conducted an MTT assay to assess the cytotoxicity of nCur-mediated PDI in combination with nanosilver colistin. The fractional biofilm inhibitory concentration (FBIC) of two P. aeruginosa clinical isolates and P. aeruginosa ATCC 27853 during nCur-mediated PDI@AgNPs@CL was determined using a 3-dimensional (3-D) checkerboard assay. To study the effect of nCur-mediated PDI@AgNPs@CL on lasI, lasR, rhlI, rhlR, pelA, and pslA gene expression, Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was conducted at each isolate's FBIC. The impact of treatments was also investigated using scanning electron microscopy (SEM).

RESULTS

The ZP and mean DLS values of the nCur were 10.3 mV and 402.6 ± 24.6 nm, respectively. The distinct functional groups of nCur corresponded with the peaks of FTIR absorption. Moreover, the EDX analysis showed the ratios of different metals in nCur. Cell viability percentages of nCur-mediated PDI@AgNPs@CL at FBIC concentrations of clinical isolates Nos. 30, 354, and P. aeruginosa ATCC 27853 were 91.36 %, 83.20 %, and 92.48 %, respectively. nCur-mediated PDI@AgNPs@CL treatment showed synergistic effects in clinical isolates and P. aeruginosa ATCC 27853 in a 3-D checkerboard assay. All six of the investigated genes showed down-regulation after nCur-mediated PDI@AgNPs@CL treatment. The most suppressed gene during nCur-mediated PDI@AgNPs@CL treatment was the rhlR gene (-11.9-fold) of P. aeruginosa ATCC 27853. The SEM micrographs further proved the connecting cement reduction and biofilm mass mitigation following nCur-mediated PDI@AgNPs@CL treatments.

CONCLUSIONS

The combined effect of nCur-mediated PDI and AgNPs@CL synergistically reduce the formation of biofilm in P. aeruginosa. This may be attributable to the suppression of the genes responsible for regulating the production of biofilms.

Gum Arabic-mediated synthesis of silver nanoparticles for their applications as colorimetric and SERS-based detection of hydrogen peroxide

We report on the one-step green method to synthesize Gum Arabic stabilized silver nanoparticles (GA-Ag NPs). The synthesized particles are monodispersed and in the size range of 15-20 nm. The synthesized Ag NPs are used as a colorimetric sensor for the detection of H2O2 and glucose with a detection limit of 11.7 nM and 0.13 µM, respectively. The sensor has also been used for the detection of H2O2 in water samples and glucose in human blood serum samples. The GA-Ag NPs decorated on filter paper have also shown excellent SERS activity for the detection of H2O2 with a detection limit of 0.56 µM.