Synthesis and biochemical characterization of silver nanoparticles grafted chitosan (Chi-Ag-NPs): in vitro studies on antioxidant and antibacterial applications

Establishing a productive heterogeneous catalyst based on silver nanoparticles supported on a crosslinked vinyl polymer for the reduction of nitrophenol

The treatment of toxic nitrophenols in industrial wastewater is urgently needed from environmental, health, and economic points of view. The current study addresses the synthesis of the crosslinked vinyl polymer poly(acrylonitrile-co-2-acrylamido-2-methylpropane sulfonic acid) (poly(AN-co-AMPS)) through free radical copolymerization techniques using acrylonitrile (AN) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) monomers with different ratios and potassium persulfate (KPS) as an initiator in an aqueous medium. The prepared copolymer was utilized as a supporting matrix for silver nanoparticles (AgNPs) via the chemical reduction of silver nitrate within the copolymer framework. Different techniques were employed to characterize the prepared poly(AN-co-AMPS) and Ag/poly(AN-co-AMPS) composites, such as Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) analysis. The results exhibit that silver metal was excellently dispersed across the surface of poly(AN-co-AMPS) without any agglomeration, presenting as nanocrystals with an average particle size equal to 6.21 nm. Also, BET analysis confirmed that the Ag/poly(AN-co-AMPS) composite exhibits mesoporous characteristics with a surface area of 59.615 m2 g-1. Moreover, the Ag/poly(AN-co-AMPS) composite was effectively applied as a heterogeneous catalyst for the catalytic reduction of hazardous 4-nitrophenols (4-NP) with a rate constant equal to 0.28 min-1 and half-life time equal to 2.47 min to a less toxic compound in the presence of NaBH4 as a reductant. Furthermore, the reusability experiment confirmed the excellent stability of Ag/poly(AN-co-AMPS). The catalyst can be easily separated from the reaction mixture using a simple centrifuge and directly reused for up to four successive cycles without a remarkable decrease in its catalytic activity. The conversion percentage of 4-NP after the four cycles was found to be 93%.

Accelerated full-thickness skin wound tissue regeneration by self-crosslinked chitosan hydrogel films reinforced by oxidized CNC-AgNPs stabilized Pickering emulsion for quercetin delivery

BACKGROUND

The non-toxic self-crosslinked hydrogel films designed from biocompatible materials allow for controlled drug release and have gathered remarkable attention from healthcare professionals as wound dressing materials. Thus, in the current study the chitosan (CS) film is infused with oil-in-water Pickering emulsion (PE) loaded with bioactive compound quercetin (Qu) and stabilized by dialdehyde cellulose nanocrystal-silver nanoparticles (DCNC-AgNPs). The DCNC-AgNPs play a dual role in stabilizing PE and are involved in the self-crosslinking with CS films. Also, this film could combine the advantage of the controlled release and synergistic wound-healing effect of Qu and AgNPs.

RESULTS

The DCNC-AgNPs were synthesized using sodium periodate oxidation of CNC. The DCNC-AgNPs were used to stabilize oil-in-water PE loaded with Qu in its oil phase by high speed homogenization. Stable PEs were prepared by 20% v/v oil: water ratio with maximum encapsulation of Qu in the oil phase. The Qu-loaded PE was then added to CS solution (50% v/v) to prepare self-crosslinked films (CS-PE-Qu). After grafting CS films with PE, the surface and cross-sectional SEM images show an inter-penetrated network within the matrix between DCNC and CS due to the formation of a Schiff base bond between the reactive aldehyde groups of DCNC-AgNPs and amino groups of CS. Further, the addition of glycerol influenced the extensibility, swelling ratio, and drug release of the films. The fabricated CS-PE-Qu films were analyzed for their wound healing and tissue regeneration potential using cell scratch assay and full-thickness excisional skin wound model in mice. The as-fabricated CS-PE-Qu films showed great biocompatibility, increased HaCat cell migration, and promoted collagen synthesis in HDFa cells. In addition, the CS-PE-Qu films exhibited non-hemolysis and improved wound closure rate in mice compared to CS, CS-Qu, and CS-blank PE. The H&E staining of the wounded skin tissue indicated the wounded tissue regeneration in CS-PE-Qu films treated mice.

CONCLUSION

Results obtained here confirm the wound healing benefits of CS-PE-Qu films and project them as promising biocompatible material and well suited for full-thickness wound healing in clinical applications.

Endophytic Aspergillus hiratsukae mediated biosynthesis of silver nanoparticles and their antimicrobial and photocatalytic activities

In the current study, endophytic Aspergillus hiratsukae was used for the biosynthesis of silver nanoparticles (Ag-NPs) for the first time. The characterizations were performed using X ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), Dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), and UV-Vis spectroscopy. The obtained results demonstrated the successful formation of crystalline, spherical Ag-NPs with particle diameters ranging from 16 to 31 nm. The FT-IR studied and displayed the various functional groups involved, which played a role in capping and reducing agents for Ag-NPs production. The SEM-EDX revealed that the main constituent of the AS-formed sample was primarily Ag, with a weight percentage of 64.2%. The mycosynthesized Ag-NPs were assessed for antimicrobial as well as photocatalytic activities. The antimicrobial results indicated that the synthesized Ag-NPs possess notable antibacterial efficacy against Staphylococcus aureus, Bacillus subtilis, and Escherichia coli, with minimum inhibitory concentrations (MICs) of Ag-NPs ranging from 62.5 to 250 μg/mL. Moreover, the biosynthesized Ag-NPs demonstrated weak antifungal activity against Aspergillus brasiliensis and Candida albicans, with MICs of 500 and 1,000 μg/mL, respectively. In addition, the mycosynthesized Ag-NPs exhibited photocatalytic activity toward acid black 2 (nigrosine) dye under both light and dark stimulation. Notably, After 300 min exposure to light, the nigrosine dye was degraded by 93%. In contrast, 51% degradation was observed after 300 min in darkness. In conclusion, Ag-NPs were successfully biosynthesized using endophytic A. hiratsukae and also exhibited antimicrobial and photocatalytic activities that can be used in environmental applications.

Advances in preparation, biomedical, and pharmaceutical applications of chitosan-based gold, silver, and magnetic nanoparticles: A review

During the last decades, the ever-increasing incidence of various diseases, like cancer, has led to a high rate of death worldwide. On the other hand, conventional modalities (such as chemotherapy and radiotherapy) have not indicated enough efficiency in the diagnosis and treatment of diseases. Thus, potential novel approaches should be taken into consideration to pave the way for the suppression of diseases. Among novel approaches, biomaterials, like chitosan nanoparticles (CS NPs, N-acetyl-glucosamine and D-glucosamine), have been approved by the FDA for some efficient pharmaceutical applications. These NPs owing to their physicochemical properties, modification with different molecules, biocompatibility, serum stability, less immune response, suitable pharmacokinetics and pharmacodynamics, etc. have received deep attention among researchers and clinicians. More importantly, the impact of CS polysaccharide in the synthesis, preparation, and delivery of metallic NPs (like gold, silver, and magnetic NPs), and combination of CS with these metallic NPs can further facilitate the diagnosis and treatment of diseases. Metallic NPs possess some features, like converting NIR photon energy into thermal energy and anti-microorganism capability, and can be a potential candidate for the diagnosis and treatment of diseases in combination with CS NPs. These combined NPs would be efficient pharmaceuticals in the future.

Biomaterial composed of chitosan, riboflavin, and hydroxyapatite for bone tissue regeneration

Biomaterial engineering approaches involve using a combination of miscellaneous bioactive molecules which may promote cell proliferation and, thus, form a scaffold with the environment that favors the regeneration process. Chitosan, a naturally occurring biodegradable polymer, possess some essential features, i.e., biodegradability, biocompatibility, and in the solid phase good porosity, which may contribute to promote cell adhesion. Moreover, doping of the materials with other biocompounds will create a unique and multifunctional scaffold that will be useful in regenerative medicine. This study is focused on the manufacturing and characterization of composite materials based on chitosan, hydroxyapatite, and riboflavin. The resulting films were fabricated by the casting/solvent evaporation method. Morphological and spectroscopy analyses of the films revealed a porous structure and an interconnection between chitosan and apatite. The composite material showed an inhibitory effect on Staphylococcus aureus and exhibited higher antioxidant activity compared to pure chitosan. In vitro studies on riboflavin showed increased cell proliferation and migration of fibroblasts and osteosarcoma cells, thus demonstrating their potential for bone tissue engineering applications.

Adsorption-photocatalytic degradation abilities of γ-irradiated chitosan-ZnO-AgNP composite for organic dye removal and antibacterial activity

We synthesized a γ-irradiated chitosan-ZnO-AgNPs (ICZA) composite by using a simple hydrogels method. We evaluated its adsorption/photocatalytic degradation abilities for the removal of an organic dye and its antibacterial activity. The XRD, SEM, TEM, EDS, and FTIR techniques were used to characterize the obtained samples. Based on the adsorption and degradation of methylene blue (MB) in the dark and under UV light irradiation, the adsorption and the photocatalytic activity of the as-obtained samples were evaluated. The optimum conditions for synthesizing the composite were as follows: contact time of 210 min, a dosage of 2 g/L, MB concentration of 40 mg/L, and a solution pH of 8.0. The ICZA had a high adsorption capacity, which was suitable for removing MB from the aqueous solutions; it showed a maximum adsorption capacity (qm) of 92.59 mg/g. The fit of the adsorption isotherms with the Langmuir model was satisfactory. The photocatalytic degradation ability of the composite was also better than that of other catalysts in the presence of UV light, with an apparent rate constant (kapp) of 3.08 × 10-2. The synthesized ICZA also showed good antibacterial activity against Staphylococcus aureus, with a minimum inhibitory concentration (MIC) and a minimum bactericidal concentration (MBC) of 12.5 g/mL and 50 g/mL under light-incubation and dark-incubation conditions. Finally, we discussed the hypothesized mechanism of the adsorption/photocatalytic activity and antibacterial activity of the ICZA composite in this study.

Comparative study of microscale and macroscale technique for encapsulation of Calotropis gigantea extract in metal-conjugated nanomatrices for invasive ductal carcinoma

The encapsulation of plant extract in nanomatrices has limitations due to its adhesion to walls, size control, high cost and long durations that results in low yield. Macroscale and microscale level techniques for development of micro/nanoparticles may impact the encapsulation of plant extract. This study aimed to evaluate the relative efficiency of microscale and macroscale techniques for encapsulation of plant extract, which is not compared yet. Keeping this in view, encapsulation of Calotropis gigantea leaves extract (CaG) was attained in silver-conjugated poliglusam nanomatrices (POL/Ag) to induce apoptosis in invasive ductal carcinoma (IDC) cells. The ethanolic CaG extract was prepared using percolation method and characterized by chemical tests for its active phytochemical compounds. The droplet-based microfluidic system was utilized as microscale encapsulation technique for CaG in nanomatrices at two different aqueous to oil flow rate ratios 1.0:1.5, and 1.0:3.0. Moreover, conventional batch system was utilized as macroscale encapsulation technique consisted of hot plate magnetic stirrer. The prepared nanomatrices were analysed for antioxidant activity using DPPH test and for cytotoxicity analysis using MCF-7 cells. The characteristic peaks of UV-Vis, FTIR and XRD spectrum confirmed the synthesis of CaG(POL/Ag) by both the encapsulation methods. However, microfluidic system was found to be more expedient because of attaining small and uniform sized silver nanoparticles (92 ± 19 nm) at high flow rate and achieving high encapsulation efficiency (80.25%) as compared to the conventional batch method (52.5%). CaG(POL/Ag) nanomatrices found to have significant antioxidant activity (p = 0.0014) against DPPH radical scavenging activity. The CaG(POL/Ag) of the smallest sized formulated by the microfluidic system has also shown the highest cytotoxicity (90%) as compared to batch method (70%) at 80 µg/mL. Our results indicate that the microscale technique using microfluidic system is a more efficient method to formulate size-controlled CaG(POL/Ag) nanomatrices and achieve high encapsulation of plant extract. Additionally, CaG(Pol/Ag) was found to be an efficient new combination for inducing potent (p < 0.0001) apoptosis in IDC cells. Therefore, CaG(Pol/Ag) can be further tested as an anti-cancer agent for in-vivo experiments.

Synthesis of Chitosan-Silver Nanocomposite and Its Evaluation as an Antibacterial Coating for Mobile Phone Glass Protectors

An easy and environment-friendly route for antibacterial coating suited for mobile phone glass protectors was successfully demonstrated. In this route, freshly prepared chitosan solution in 1% v/v acetic acid was added with 0.1 M silver nitrate solution and 0.1 M sodium hydroxide solution and incubated with agitation at 70 °C to form chitosan-silver nanoparticles (ChAgNPs). Varied concentrations of chitosan solution (i.e., 0.1, 0.2, 0.4, 0.6, and 0.8% w/v) were used to investigate its particle size, size distribution, and later on, its antibacterial activity. Transmission electron microscope (TEM) imaging revealed that the smallest average diameter of silver nanoparticles (AgNPs) was 13.04 nm from 0.8% w/v chitosan solution. Further characterizations of the optimal nanocomposite formulation using UV-vis spectroscopy and Fourier transfer infrared spectroscopy were also performed. Using a dynamic light scattering zetasizer, the average ζ-potential of the optimal ChAgNP formulation was at +56.07 mV, showing high aggregative stability and an average ChAgNP size of 182.37 nm. The ChAgNP nanocoating on glass protectors shows antibacterial activity against Escherichia coli (E. coli) at 24 and 48 h of contact. However, the antibacterial activity decreased from 49.80% (24 h) to 32.60% (48 h).

Chitosan and chito-oligosaccharide: a versatile biopolymer with endless grafting possibilities for multifarious applications

Chito-oligosaccharides (COS), derived from chitosan (CH), are attracting increasing attention as drug delivery carriers due to their biocompatibility, biodegradability, and mucoadhesive properties. Grafting, the process of chemically modifying CH/COS by adding side chains, has been used to improve their drug delivery performance by enhancing their stability, targeted delivery, and controlled release. In this review, we aim to provide an in-depth study on the recent advances in the grafting of CH/COS for multifarious applications. Moreover, the various strategies and techniques used for grafting, including chemical modification, enzymatic modification, and physical modification, are elaborated. The properties of grafted CH/COS, such as stability, solubility, and biocompatibility, were reported. Additionally, the review detailed the various applications of grafted CH/COS in drug delivery, including the delivery of small drug molecule, proteins, and RNA interference therapeutics. Furthermore, the effectiveness of grafted CH/COS in improving the pharmacokinetics and pharmacodynamics of drugs was included. Finally, the challenges and limitations associated with the use of grafted CH/COS for drug delivery and outline directions for future research are addressed. The insights provided in this review will be valuable for researchers and drug development professionals interested in the application of grafted CH/COS for multifarious applications.

New sustainable antimicrobial chitosan hydrogels based on sulfonamides and its nanocomposites: Fabrication and characterization

Chitosan (Ch), a linear cationic biopolymer, has a broad medical applications. In this paper, new sustainable hydrogels (Ch-3,Ch-5_a,Ch-5_b) based on chitosan/sulfonamide derivatives 2-chloro-N-(4-sulfamoylphenethyl) acetamide (3) and/or 5-[(4-sulfamoylphenethyl) carbamoyl] isobenzofuran-1,3-dione (5) were prepared. Hydrogels (Ch-3, Ch-5_a, Ch-5_b) were loaded (Au,Ag,ZnO) NPs to form its nanocomposites to improve the antimicrobial efficacy of chitosan. The structures of hydrogels and its nanocomposites were characterized using different tools. All hydrogels displayed irregular surface morphology in SEM, however hydrogel (Ch-5_a) revealed the highest crystallinity. The highest thermal stability was shown by hydrogel (Ch-5_b) compared to chitosan. The nanocomposites represented nanoparticle sizes <100 nm. Antimicrobial activity was assayed for hydrogels using disc diffusion method exhibited great inhibition growth of bacteria compared to chitosan against S. aureus, B. subtilis and S. epidermidis as Gram-positive, E. coli, Proteus, and K. pneumonia as Gram-negative and antifungal activity against Aspergillus Niger and Candida. Hydrogel (Ch-5_b) and nanocomposite hydrogel (Ch-3/Ag NPs) showed higher colony forming unit (CFU) and reduction% against S. aureus and E. coli reaching 97.96 % and 89.50 % respectively in comparison with 74.56 % and 40.30 % for chitosan respectively. Overall, fabricated hydrogels and its nanocomposites enhanced the biological activity of chitosan and it can be potential candidate as antimicrobial drugs.

Development of Decellularized Fish Skin Scaffold Decorated with Biosynthesized Silver Nanoparticles for Accelerated Burn Wound Healing

In this study, decellularized fish skin (DFS) scaffold decorated with silver nanoparticles was prepared for accelerating burn wound healing. The silver nanoparticles (AgNPs) synthesized by the green and facile method using Aloe vera leaf at different incubating times were characterized by using X-ray Diffraction (XRD), Fourier Transform Infrared (FT-IR) Spectroscopy, and Ultraviolet-Visible Spectroscopy (UV-Vis spectroscopy). The different characterizations confirmed that the sizes of AgNPs prepared by incubating for 6 hours and 12 hours were 29.1 nm and 35.2 nm, respectively. After that, the different concentrations of the smallest AgNPs were used to dope the DFS scaffold to determine the cell viability. Additionally, an agar well diffusion method was used to screen for antimicrobial activity. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were used to correlate the concentration of AgNPs with its bactericidal effect which was seen from 50 μg/ml. Then, the toxicity with human cells was investigated using a 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay with no significant cell viability from the concentration of 50 μg/ml to 200 μg/ml compared to the cocultured and commercial treatments.

Self-Standing Bioinspired Polymer Films Doped with Ultrafine Silver Nanoparticles as Innovative Antimicrobial Material

Thin self-standing films with potential antimicrobial synergistic activity have been produced by a simple green chemical synthesis with overnight thermal treatment. Their properties have been studied by scanning electron microscopy, X-ray photoelectron spectroscopy and other techniques to understand their potential range of applications. In this work, the focus was set on the development of a potential novel and effective alternative to conventional antimicrobial materials. By creating an antimicrobial polymer blend, and using it to develop and immobilize fine (~25 nm) silver nanophases, we further aimed to exploit its film-forming properties and create a solid composite material. The resulting polymer matrix showed improved water uptake percentage and better stability in the presence of water. Moreover, the antimicrobial activity of the films, which is due to both organic and inorganic components, has been evaluated by Kirby-Bauer assay against common foodborne pathogens (Staphylococcus aureus and Salmonella enterica) and resulted in a clear inhibition zone of 1.2 cm for the most complex nanocomposition. The excellent performance against bacteria of fresh and 6-month-old samples proves the prospects of this material for the development of smart and biodegradable food packaging applications.

Chitosan-Coated Polymeric Silver and Gold Nanoparticles: Biosynthesis, Characterization and Potential Antibacterial Applications: A Review

Biosynthesized metal nanoparticles, especially silver and gold nanoparticles, and their conjugates with biopolymers have immense potential in various fields of science due to their enormous applications, including biomedical applications. Polymeric nanoparticles are particles of small sizes from 1 nm to 1000 nm. Among different polymeric nanoparticles, chitosan-coated silver and gold nanoparticles have gained significant interest from researchers due to their various biomedical applications, such as anti-cancer, antibacterial, antiviral, antifungal, anti-inflammatory technologies, as well as targeted drug delivery, etc. Multidrug-resistant pathogenic bacteria have become a serious threat to public health day by day. Novel, effective, and safe antibacterial agents are required to control these multidrug-resistant pathogenic microorganisms. Chitosan-coated silver and gold nanoparticles could be effective and safe agents for controlling these pathogens. It is proven that both chitosan and silver or gold nanoparticles have strong antibacterial activity. By the conjugation of biopolymer chitosan with silver or gold nanoparticles, the stability and antibacterial efficacy against multidrug-resistant pathogenic bacteria will be increased significantly, as well as their toxicity in humans being decreased. In recent years, chitosan-coated silver and gold nanoparticles have been increasingly investigated due to their potential applications in nanomedicine. This review discusses the biologically facile, rapid, and ecofriendly synthesis of chitosan-coated silver and gold nanoparticles; their characterization; and potential antibacterial applications against multidrug-resistant pathogenic bacteria.

Chitosan-Based Formulations Intended as Protective Spray for Mask Surfaces in Prevention of Coronavirus Dissemination

The extraordinary occurrence of COVID-19 by the fast expansion of viral infections has propelled particular interest in developing novel antiviral and virucidal agents to guarantee personal security. The main objective of this work is to propose novel formulations able to optimize the use of personal protection elements. In recent years, chitosan (CH) has attracted attention for being an interesting multifunctional, biodegradable, non-antigenic, non-toxic, and biocompatible natural polymer with antimicrobial properties. In this work, formulations based on a CH matrix containing silver, and Copper based nanoparticles have been developed. The novelty of this proposal is that almost liquid formulations have been reached, possessing verified properties to inhibit evolved virus such as herpes simplex type 1 (HSV-1) and bovine betacoronavirus (BCoV), the latter belonging to the same family of the well-known the well-known SARS-CoV-2. Besides antibacterial bioactivity; as well as the ability of these formulations to be easily sprayed on various surfaces, including conventional face masks, have been verified and discussed. The results presented in this contribution provide strong evidence on CH films as an ideal biosafe surface-protective for several daily used materials including the conventional face masks.

Composite Coatings of Chitosan and Silver Nanoparticles Obtained by Galvanic Deposition for Orthopedic Implants

In this work, composite coatings of chitosan and silver nanoparticles were presented as an antibacterial coating for orthopedic implants. Coatings were deposited on AISI 304L using the galvanic deposition method. In galvanic deposition, the difference of the electrochemical redox potential between two metals (the substrate and a sacrificial anode) has the pivotal role in the process. In the coupling of these two metals a spontaneous redox reaction occurs and thus no external power supply is necessary. Using this process, a uniform deposition on the exposed area and a good adherence of the composite coating on the metallic substrate were achieved. Physical-chemical characterizations were carried out to evaluate morphology, chemical composition, and the presence of silver nanoparticles. These characterizations have shown the deposition of coatings with homogenous and porous surface structures with silver nanoparticles incorporated and distributed into the polymeric matrix. Corrosion tests were also carried out in a simulated body fluid at 37 °C in order to simulate the same physiological conditions. Corrosion potential and corrosion current density were obtained from the polarization curves by Tafel extrapolation. The results show an improvement in protection against corrosion phenomena compared to bare AISI 304L. Furthermore, the ability of the coating to release the Ag+ was evaluated in the simulated body fluid at 37 °C and it was found that the release mechanism switches from anomalous to diffusion controlled after 3 h.

Modification of Thin Film Composite Membrane by Chitosan-Silver Particles to Improve Desalination and Anti-Biofouling Performance

Reverse osmosis (RO) desalination is a technology that is commonly used to mitigate water scarcity problems; one of its disadvantages is the bio-fouling of the membranes used, which reduces its performance. In order to minimize this problem, this study prepared modified thin film composite (TFC) membranes by the incorporation of chitosan-silver particles (CS-Ag) of different molecular weights, and evaluated them in terms of their anti-biofouling and desalination performances. The CS-Ag were obtained using ionotropic gelation, and were characterized by Fourier transform infrared spectroscopy (FTIR), high-resolution scanning electron microscopy (HR-SEM), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA) and dynamic light scattering (DLS). The modified membranes were synthetized by the incorporation of the CS-Ag using the interfacial polymerization method. The membranes (MCS-Ag) were characterized by Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and contact angle. Bactericidal tests by total cell count were performed using Bacillus halotolerans MCC1, and anti-adhesion properties were confirmed through biofilm cake layer thickness and total organic carbon (%). The desalination performance was defined by permeate flux, hydraulic resistance, salt rejection and salt permeance by using 2000 and 5000 mg L^-1 of NaCl. The MCS-Ag-L presented superior permeate flux and salt rejection (63.3% and 1% higher, respectively), as well as higher bactericidal properties (76% less in total cell count) and anti-adhesion capacity (biofilm thickness layer 60% and total organic carbon 75% less, compared with the unmodified membrane). The highest hydraulic resistance value was for MCS-Ag-M. In conclusion, the molecular weight of CS-Ag significantly influences the desalination and the antimicrobial performances of the membranes; as the molecular weight decreases, the membranes' performances increase. This study shows a possible alternative for increasing membrane useful life in the desalination process.

Green Synthesis of Silver Nanoparticles Coated by Water Soluble Chitosan and Its Potency as Non-Alcoholic Hand Sanitizer Formulation

The synthesis of silver nanoparticles using plant extracts, widely known as a green synthesis method, has been extensively studied. Nanoparticles produced through this method have applications as antibacterial agents. Bacterial and viral infection can be prevented by use of antibacterial agents such as soap, disinfectants, and hand sanitizer. Silver nanoparticles represent promising hand sanitizer ingredients due to their antibacterial activity and can enable reduced use of alcohol and triclosan. This study employed silver nanoparticles synthesized using Kepok banana peel extract (Musa paradisiaca L.). Nanoparticle effectiveness as a hand sanitizer can be enhanced by coating with a biocompatible polymer such as chitosan. The characterization of silver nanoparticles was conducted using UV-Vis, with an obtained peak at 434.5 nm. SEM-EDX analysis indicated nanoparticles with a spherical morphology. Silver nanoparticles coated with chitosan were characterized through FTIR to verify the attached functional groups. Gel hand sanitizers were produced using silver nanoparticles coated with different chitosan concentrations. Several tests were undertaken to determine the gel characteristics, including pH, syneresis, and antibacterial activity. Syneresis leads to unstable gels, but was found to be inhibited by adding chitosan at a concentration of 2%. Antibacterial activity was found to increase with increase in chitosan concentration.

Multifunctional Silver Nanoparticles Based on Chitosan: Antibacterial, Antibiofilm, Antifungal, Antioxidant, and Wound-Healing Activities

The purpose of this study is to create chitosan-stabilized silver nanoparticles (Chi/Ag-NPs) and determine whether they were cytotoxic and also to determine their characteristic antibacterial, antibiofilm, and wound healing activities. Recently, the development of an efficient and environmentally friendly method for synthesizing metal nanoparticles based on polysaccharides has attracted a lot of interest in the field of nanotechnology. Colloidal Chi/Ag-NPs are prepared by chemical reduction of silver ions in the presence of Chi, giving Chi/Ag-NPs. Physiochemical properties are determined by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) analyses. TEM pictures indicate that the generated Chi/Ag-NPs are nearly spherical in shape with a thin chitosan covering around the Ag core and had sizes in the range of 9–65 nm. In vitro antibacterial activity was evaluated against Staphylococcus aureus and Pseudomonas aeruginosa by a resazurin-mediated microtiter plate assay. The highest activity was observed with the lowest concentration of Chi/Ag-NPs, which was 12.5 µg/mL for both bacterial strains. Additionally, Chi/Ag-NPs showed promising antifungal features against Candida albicans, Aspergillus fumigatus, Aspergillus terreus, and Aspergillus niger, where inhibition zones were 22, 29, 20, and 17 mm, respectively. Likewise, Chi/Ag-NPs revealed potential antioxidant activity is 92, 90, and 75% at concentrations of 4000, 2000, and 1000 µg/mL, where the IC₅₀ of Chi/Ag-NPs was 261 µg/mL. Wound healing results illustrated that fibroblasts advanced toward the opening to close the scratch wound by roughly 50.5% after a 24-h exposure to Chi/Ag-NPs, greatly accelerating the wound healing process. In conclusion, a nanocomposite based on AgNPs and chitosan was successfully prepared and exhibited antibacterial, antibiofilm, antifungal, antioxidant, and wound healing activities that can be used in the medical field.

Non-Thermal Plasma Reduction of Ag+ Ions into Silver Nanoparticles in Open Atmosphere under Statistically Optimized Conditions for Biological and Photocatalytic Applications

An environmentally friendly non-thermal DC plasma reduction route was adopted to reduce Ag+ ions at the plasma−liquid interface into silver nanoparticles (AgNPs) under statistically optimized conditions for biological and photocatalytic applications. The efficiency and reactivity of AgNPs were improved by statistically optimizing the reaction parameters with a Box−Behnken Design (BBD). The size of the AgNPs was chosen as a statistical response parameter, while the concentration of the stabilizer, the concentration of the silver salt, and the plasma reaction time were chosen as independent factors. The optimized parameters for the plasma production of AgNPs were estimated using a response surface methodology and a significant model p < 0.05. The AgNPs, prepared under optimized conditions, were characterized and then tested for their antibacterial, antioxidant, and photocatalytic potentials. The optimal conditions for these three activities were 3 mM of stabilizing agent, 5 mM of AgNO3, and 30 min of reaction time. Having particles size of 19 to 37 nm under optimized conditions, the AgNPs revealed a 82.3% degradation of methyl orange dye under UV light irradiation. The antibacterial response of the optimized AgNPs against S. aureus and E. coli strains revealed inhabitation zones of 15 mm and 12 mm, respectively, which demonstrate an antioxidant activity of 81.2%.

Coating of silver nanoparticles on polyurethane film surface by green chemistry approach and investigation of antibacterial activity against S. epidermidis

Silver nanoparticles with potential antibacterial properties are included in biomaterials for the production of medical devices, which are used for diagnoses or treatment purposes. The aim of the current study was coating the polyurethane (PU) films with silver nanoparticles (AgNPs) due to their antibacterial efficacy. PU films were first modified by chitosan (CH), treated with AgNO3 to let CH chelate with silver ions, and then treated with vitamin-C (vit C) or glucose (Glu) to reduce the adsorbed ions to atomic silver to form AgNPs. The surfaces of the films were examined by ATR-FTIR, XPS, XRD, and SEM. Chemical bond formation between CH and Ag ions and AgNPs were determined by ATR-FTIR. Meanwhile, XPS and SEM analyses proved the presence of reduced metallic silver and nanoparticles on the film surfaces, respectively. According to the SEM analyses, a homogeneous distribution of AgNPs, with sizes 99–214 nm and 37–54 nm, on the film surfaces were obtained depending on Glu or vit C reduction, respectively. The films presented excellent antibacterial performance against Gram positive Staphylococcus epidermidis ( S. epidermidis). These results suggested that the mentioned green technology can be easily applied to obtain AgNP coated polymeric surfaces with very high antibacterial efficacy. Although there are some studies dealing with AgNP formation on PU sponges or fibers, to the best of our knowledge, this is the first study showing AgNP formation on the CH conjugated PU films.

Overview of the Influence of Silver, Gold, and Titanium Nanoparticles on the Physical Properties of PEDOT:PSS-Coated Cotton Fabrics

Metallic nanoparticles have been of interest to scientists, and they are now widely used in biomedical and engineering applications. The importance, categorization, and characterization of silver nanoparticles, gold nanoparticles, and titanium nanoparticles have been discussed. Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) is the most practical and reliable conductive polymer used in the manufacturing of conductive textiles. The effects of metallic nanoparticles on the performance of PEDOT:PSS thin films are discussed. The results indicated that the properties of PEDOT:PSS significantly depended on the synthesis technique, doping, post-treatment, and composite material. Further, electronic textiles known as smart textiles have recently gained popularity, and they offer a wide range of applications. This review provides an overview of the effects of nanoparticles on the physical properties of PEDOT:PSS-coated cotton fabrics.

Preparation, Characterization, and Antimicrobial and Antiviral Properties of Silver-Containing Nanocomposites Based on Polylactic Acid-Chitosan

Antimicrobial and antiviral nanocomposites based on polylactic acid (PLA) and chitosan were synthesized by a thermochemical reduction method of Ag⁺ ions in the PLA-Ag⁺-chitosan polymer films. Features of the structural, morphological, thermophysical, antimicrobial, antiviral, and cytotoxic properties of PLA-Ag-chitosan nanocomposites were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and antiviral, antimicrobial, and cytotoxic studies. The effects of temperature and the duration of reduction of Ag⁺ ions on the structure of PLA-Ag-chitosan nanocomposites were established. During the thermochemical reduction (T = 160 °C, t = 5 min) of silver palmitate ions in PLA-Ag⁺-chitosan polymer films, Ag nanoparticles with an average size of 4.2 nm were formed. PLA-Ag-chitosan polymer nanocomposites have strong antimicrobial activity against S. aureus and E. coli strains. In particular, for PLA-chitosan samples containing 4% Ag, the diameters of the S. aureus and E. coli growth inhibition zones were 25.8 and 25.0 mm, respectively. The antiviral activity of the nanocomposites against influenza A virus, herpes simplex virus type 1, and adenovirus serotype 2 was also revealed. The PLA-4%Ag-chitosan nanocomposites completely inhibited the cytopathic effect (CPE) of herpes virus type 1 by 5.12 log₁₀TCID₅₀/mL (high antiviral activity) and the development of the CPE of influenza virus and adenovirus by 0.60 and 1.07 log₁₀TCID₅₀/mL (relative antiviral activity). The obtained nanocomposites were not cytotoxic; they did not inhibit the viability of MDCK, BHK-21, and Hep-2 cell cultures.

Development of Chitosan Silver Nanocomposites: Its Characteristic Study and Toxicity Effect against 3T3-L1 Cell Line

Nanocomposite from the natural source is opened a wide area for the researchers to find a natural remedy to replace the chemicals or harmful products in all the fields of agricultural, food and medical fields. Here the biopolymer (chitosan) was extracted from the two white rot fungi of Pleurotus floridanus and Pleurotus djamor, and biologically synthesized with 1mM AgNO3 solution. Synthesized chitosan nanocomposite was characterized with UV-Visible study, FTIR, FESEM, XRD, EDAS for the confirmation based upon the peaks, functional group, crystalline nature, size, morphology and the percentage of elements respectively. Toxicity study was carried out using 3T3 L1 (Mouse embryo fibroblast Cell Line) normal Cell Line to find out the cytotoxicity effect of the chitosan nanocomposite and found that the nanocomposites were non toxic to the Cell Line.

Silk Sericin Enrichment through Electrodeposition and Carbonous Materials for the Removal of Methylene Blue from Aqueous Solution

The recycling and reuse of biomass waste for the preparation of carbon-based adsorbents is a sustainable development strategy that has a positive environmental impact. It is well known that a large amount of silk sericin (SS) is dissolved in the wastewater from the silk industry. Utilizing the SS instead of discharging it into the environment without further treatment would reduce environmental and ecological problems. However, effective enrichment of the SS from the aqueous solution is a challenge. Here, with the help of carboxymethyl chitosan (CMCS), which can form a gel structure under low voltage, an SS/CMCS hydrogel with SS as the major component was prepared via electrodeposition at a 3 V direct-current (DC) voltage for five minutes. Following a carbonization process, an SS-based adsorbent with good performance for the removal of methylene blue (MB) from an aqueous solution was prepared. Our results reveal that the SS/CMCS hydrogel maintains a porous architecture before and after carbonization. Such structure provides abundant adsorption sites facilitating the adsorption of MB molecules, with a maximum adsorptive capacity of 231.79 mg/g. In addition, it suggests that the adsorption is an exothermic process, has a good fit with the Langmuir model, and follows the intra-particle diffusion model. The presented work provides an economical and feasible path for the treatment of wastewater from dyeing and printing.

Optimization of anti-corrosion performance of novel magnetic polyaniline-Chitosan nanocomposite decorated with silver nanoparticles on Al in simulated acidizing environment using RSM

The suitability of newly synthesized magnetic polyaniline-Chitosan nanocomposite decorated with silver nanoparticles (Ag@PANI-CS-Fe₃O₄) as a robust corrosion inhibitor for Aluminum (Al) in a 5 M HCl environment has been investigated via Weight Loss (WL), Alternating Current (AC)-Impedance Spectroscopy (IS), Potentiontiodynamic polarization (Tafel plots), and Scanning Electron Microscopy (SEM) techniques. The protection efficiency (PE) was mathematically modeled using the Response Surface Methodology (RSM) to fit an empirical relation in terms of temperature, nanocomposite concentration, and time using the face-centered central composite design. The model was accurate with a coefficient of determination (R² = 99.27%). The negative Gibb's free energy of adsorption (ΔG_ads) values confirmed the spontaneity of Freundlich adsorption isotherm process on Al in 5 M HCl solution. The optimization simulation yielded maximum protection efficiency (of 97.88%) at 5 mg/L nanocomposite concentration, 1 h time, and an intermediate temperature of 304.8 K. Furthermore, the sensitivity of PE was evaluated to find that the low temperature 303 K is favorable for PE, whereas higher temperature will act adversely on PE. The results obtained by the RSM model are in agreement with the experimental observations.

Active Double-Layered Films Enriched with AgNPs in Great Water Dock Root and Pu-Erh Extracts

A novel, eco-friendly, and biocompatible method was applied to form silver nanoparticles (AgNPs) in great water dock (Lapathi radix) (KB) and pu-erh (Camellia sinensis) (PE) extracts. The surface plasma resonance peak of green synthesized AgNPs at 451.8 nm for AgNPs+KB and 440.8 nm for AgNPs+PE was observed via spectral analysis of UV absorbance. In this study, double-layered biopolymer films (FUR/CHIT+HGEL) with AgNPs incorporated in KB solution (AgNPs+KB) and AgNPs in PE solution (AgNPs+PE), were successfully prepared using the casting method. The SEM, XRD, zeta potential and size analyses confirmed the presence of AgNP in the films. The addition of AgNPs in plant extracts improved antimicrobial and antioxidant activity and thermal stability, whereas WVTR experienced a decrease. The nanocomposite films’ orange-brown colour may aid in the protection of food products against UV rays. The composite films demonstrated antibacterial activity against food-borne pathogens and may offer potential in food packaging applications.

Synthesis of silver nanoparticles using Plantago lanceolata extract and assessing their antibacterial and antioxidant activities

Silver nanoparticles (Ag. NPs) have shown a biological activity range, synthesized under different environment-friendly approaches. Ag. NPs were synthesized using aqueous crude extract (ACE) isolated from Plantago lanceolata. The ACE and Ag. NPs were characterized and assessed their biological and antioxidant activities. The existence of nanoparticles (NPs) was confirmed by color shift, atomic force microscopy (AFM), and UV-Vis's spectroscopy. The FT-IR analysis indicated the association of biomolecules (phenolic acid and flavonoids) to reduce silver (Ag⁺) ions. The SEM study demonstrated a sphere-shaped and mean size in the range of 30 ± 4 nm. The EDX spectrum revealed that the Ag. NPs were composed of 54.87% Ag with 20 nm size as identified by SEM and TEM. AFM has ended up being exceptionally useful in deciding morphological elements and the distance across of Ag. NPs in the scope of 23-30 nm. The TEM image showed aggregations of NPs and physical interaction. Ag. NPs formation also confirmed by XPS, DRS and BET studies. Ag. NPs showed efficient activity as compared to ACE, and finally, the bacterial growth was impaired by biogenic NPs. The lethal dose (LD₅₀) of Ag. NPs against Agrobacterium tumefaciens, Proteus vulgaris, Staphylococcus aureus, and Escherichia coli were 45.66%, 139.71%, 332.87%, and 45.54%, with IC50 (08.02 ± 0.68), (55.78 ± 1.01), (12.34 ± 1.35) and (11.68 ± 1.42) respectively, suppressing the growth as compared to ACE. The antioxidant capacity, i.e., 2,2-diphenyl-1-picrylhydrazyl (DPPH) of Ag. NPs were assayed. ACE and Ag. NPs achieved a peak antioxidant capacity of 62.43 ± 2.4 and 16.85 ± 0.4 μg mL^-1, compared to standard (69.60 ± 1.1 at 100 μg mL^-1) with IC₅₀ (369.5 ± 13.42 and 159.5 ± 10.52 respectively). Finally, the Ag. NPs synthesized by P. lanceolata extract have an excellent source of bioactive natural products (NP). Outstanding antioxidant, antibacterial activities have been shown by NPs and can be used in various biological techniques in future research.

Nanoencapsulation in low-molecular-weight chitosan improves in vivo antioxidant potential of black carrot anthocyanin

BACKGROUND

Anthocyanins are flavonoids that are potential antioxidant, anti-inflammatory, anti-obesity, and anti-carcinogenic nutraceutical ingredients. However, low chemical stability and low bioavailability limit the use of anthocyanins in food. Nanoencapsulation using biopolymers is a recent successful strategy for stabilization of anthocyanins. This study reports the development, characterization, and antioxidant activity of black carrot anthocyanin-loaded chitosan nanoparticles (ACNPs).

RESULTS

The ionic gelation technique yielded the ACNPs. The mean hydrodynamic diameter d and polydispersity index PDI of chitosan nanoparticles and ACNPs were found to be d = 455 nm and PDI = 0.542 respectively for chitosan nanoparticles and d = 274 nm and PDI = 0.376 respectively for ACNPs. The size distribution was bimodal. The surface topography revealed that the ACNPs are spherical and display a coacervate structure. Fourier transform infrared analysis revealed physicochemical interactions of anthocyanins with chitosan. The loading process could achieve an encapsulation efficiency of 70%. The flow behavior index η of encapsulated ACNPs samples revealed Newtonian and shear thickening characteristics. There was a marginal reduction in the in vitro antioxidant potential of anthocyanins after nanoencapsulation, as evidenced from 2,2-diphenyl-1-picrylhydrazyl, ferric reducing antioxidant power, and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) assays. Interestingly, the in vivo antioxidant potential of anthocyanins improved following nanoencapsulation, as observed in the serum antioxidant assays.

CONCLUSION

The optimized nanoencapsulation process resulted in spherical nanoparticles with appreciable encapsulation efficiency. The nanoencapsulation process improved the in vivo antioxidant activity of anthocyanins, indicating enhanced stability and bioavailability. The promising antioxidant activity of the ACNPs suggests a potential for utilization as a nutraceutical supplement. © 2021 Society of Chemical Industry.

Dynamic Mechanical Analysis and Thermal Expansion of Lignin-Based Biopolymers

Biodegradable materials investigation has become a necessity and a direction for many researchers worldwide. The main goal is to find sustainable alternatives which gradually replace plastics based on fossil resources from the market, because they are very harmful to the environment and to overall quality of life. In order to get to the stage of obtaining different functional parts from biodegradable materials, it is necessary to study their properties. Taking into account these shortcomings, this paper aims at the mechanical characterization (DMA—Dynamic Mechanical Analysis) and thermal degradation (thermogravimetric analysis (TGA)) of lignin-based biopolymers: Arboform LV3 Nature^®, Arboblend^® V2 Nature, and Arbofill^® Fichte Arboform^® LV3 Nature reinforced with aramid fibers. The tested samples were obtained by using the most common fabrication technique for polymers—injection molding. The obtained results for the DMA analysis showed separate polymeric-specific regions for each material and, based on the tanδ values between (0.37–0.54), a series of plastics could be proposed for replacement. The mechano-dynamic behavior could be correlated with the thermal expansion of biopolymers for temperatures higher than 50/55 °C, which are thermally stable up to temperatures of at least 250 °C.

Green synthesis of antibacterial and cytotoxic silver nanoparticles by Piper nigrum seed extract and development of antibacterial silver based chitosan nanocomposite

In the present study, we have used seed extract of P. nigrum as an effective reducing agent for the synthesis of silver nanoparticles (Ag NPs) and silver based chitosan nanocomposite (Ag/CS NC). The silver nanoparticles were characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and Fourier transform infrared spectroscopy (FTIR). The appearance of a surface plasmon resonance (SPR) peak located at 430 nm reveals the formation of silver nanoparticles. The TEM analysis indicates that the attained silver nanoparticles were mostly in spherical shapes with sizes ranging between 15 and 38 nm. The high resolution liquid chromatography with mass spectroscopy (HR-LCMS) analysis was performed to screen the phytochemical constituents of P. nigrum seed extract. The silver nanoparticles synthesized by P. nigrum seed extract exhibited effective antibacterial activity against Bacillus subtilis (B. subtilis) and Escherichia coli (E. coli). In addition, the silver nanoparticles showed potent cytotoxicity against hazardous human cancer cell lines MDA-MB-231, PANC-1, SKOV-3, PC-3 and Hela. The observation of bright spots in the TEM dark field images represents the presence of Ag in CS suspension. Besides, the Ag/CS NC coated cotton fabric substantially showed remarkable antibacterial activity against B. subtilis and E. coli.

Biological Performances of Plasmonic Biohybrids Based on Phyto-Silver/Silver Chloride Nanoparticles

Silver/silver chloride nanoparticles (Ag/AgClNPs), with a mean size of 48.2 ± 9.5 nm and a zeta potential value of -31.1 ± 1.9 mV, obtained by the Green Chemistry approach from a mixture of nettle and grape extracts, were used as "building blocks" for the "green" development of plasmonic biohybrids containing biomimetic membranes and chitosan. The mechanism of biohybrid formation was elucidated by optical analyses (UV-vis absorption and emission fluorescence, FTIR, XRD, and SAXS) and microscopic techniques (AFM and SEM). The aforementioned novel materials showed a free radical scavenging capacity of 75% and excellent antimicrobial properties against Escherichia coli (IGZ = 45 mm) and Staphylococcus aureus (IGZ = 35 mm). The antiproliferative activity of biohybrids was highlighted by a therapeutic index value of 1.30 for HT-29 cancer cells and 1.77 for HepG2 cancer cells. At concentrations below 102.2 µM, these materials are not hemolytic, so they will not be harmful when found in the bloodstream. In conclusion, hybrid systems based on phyto-Ag/AgClNPs, artificial cell membranes, and chitosan can be considered potential adjuvants in liver and colorectal cancer treatment.