Evaluation of synergistic effect of polyglycine functionalized gold/iron doped silver iodide for colorimetric detection, photocatalysis, drug delivery and bactericidal applications

Role of silver nanoparticles and silver nanoclusters for the detection and removal of Hg(ii)

Silver metal, being a 3d transition metal in group 11 in the periodic table, is widely used in material science for its distinguished plasmonic properties. Nanoparticles (NPs) and nanoclusters (NCs) are widely used in sensing applications having a surface plasmon band and emissive properties, respectively. Mercury is one of the detrimental toxins and threats to various ecosystems. The distinction between nanoparticles and nanoclusters, the utility and toxicity of heavy metal mercury, fluorometric and colorimetric approaches to the recognition of mercury ions with NPs and NCs, the mechanism of detection, spot detection, and natural water sample analyses were illustrated in detail in this review article. Moreover, the sensing platform and analyte (Hg2+) fate were described for substantiating the mechanism. It was observed that NCs are mostly utilized for fluorometric approaches, while NPs are mostly employed for colorimetric approaches. Fluorometric detection is mainly quenching-based. However, sensing with enhancement was found in a few reports. Adulteration of other metals with silver particles often modifies the sensing platform.

Formulation of silver phosphate/graphene/silica nanocomposite for enhancing the photocatalytic degradation of trypan blue dye in aqueous solution

Photocatalytic degradation of several harmful organic compounds has been presented as a potential approach to detoxify water in recent decades. Trypan Blue (TB) is an acidic azo dye used to distinguish live cells from dead ones and it's classified as a carcinogenic dye. In this study, silver phosphate (Ag3PO4) nanoparticles and novel Ag3PO4/graphene/SiO2 nanocomposite have been successfully prepared via simple precipitation method. Afterward, their physical properties, chemical composition, and morphology have been characterized using SEM, EDS, TEM, SAED, BET, XRD, FTIR and UV-VIS spectroscopy. The specific surface area of Ag3PO4 and Ag3PO4/G/SiO2 nanocomposite were reported to be 1.53 and 84.97 m2/g, respectively. The band gap energy of Ag3PO4 and Ag3PO4/G/SiO2 nanocomposite was measured to be 2.4 and 2.307 eV, respectively. Photocatalytic degradation of Trypan blue (TB) was studied at different parameters such as pH, catalyst dosage, initial concentration, and contact time. The results showed that, at initial dye concentration of 20 ppm, pH = 2, and using 0.03 g of Ag3PO4/G/SiO2 as a photocatalyst, the degradation percent of TB dye in the aqueous solution was 98.7% within 10 min of light exposure. Several adsorption isotherms such as Langmuir, Freundlich, and Temkin adsorption isotherms have been tested in addition to the photocatalytic degradation kinetics. Both catalysts were found to follow the Langmuir isotherm model and pseudo-second-order kinetic model. Finally, the possible photocatalytic performance mechanism of Ag3PO4/G/SiO2 was proposed.

Evaluation of photocatalysis inactivation in indoor air purification of pathogenic microbes by using the different nanomaterials based on TiO2 nanomaterials

The photocatalytic technology for indoor air disinfection has been broadly studied in the last decade. Selecting proper photocatalysts with high disinfection efficiency remains to be a challenge. By doping with the incorporation of metals, the bandgap can be narrowed while avoiding the recombination of photogenerated charge. Three photocatalysts (Ag-TiO2, MnO2-TiO2, and MnS2-TiO2) were tested in photocatalytic sterilization process. The results revealed that Ag-TiO2 had the best antibacterial performance. Within 20 min, the concentration of Serratia marcescens (the tested bacteria) decreased log number of ln 4.04 under 640 w/m2 light intensity with 1000 µg/mL of Ag-TiO2. During the process of inactivating bacteria, the cell membranes of bacterial was destructed and thus decreasing the activity of enzymes and releasing the cell contents, due to the generation of reactive oxygen species (O2•- and •OH) and thermal effect. Spectral regulation has the greatest impact on the sterilization efficiency of MnO2-TiO2, which reduces the probability of photocatalytic materials being excited.

Evaluating arsenic contamination in northwestern Bangladesh: A GIS-Based assessment of groundwater vulnerability and human health impacts

One of the biggest environmental worries in the world today is the risk of arsenic (As) contamination in groundwater. The Atomic Absorption Spectrometer (AAS) was used in this work to assess the As content in groundwater samples from 38 shallow (27 m) tubewells in northwest Bangladesh to determine the existing situation, potential source(s), and likely health risk of As and other important water quality parameters. The range of arsenic concentrations (μgL-1) was troublesome and greater than the WHO recommended level for drinking water, ranging from 0.50 to 164 (mean ± SD: 20.22 ± 36.46). In groundwater, the concentrations of Fe, and Mn vary from 0.04 to 52.75 mgL-1 (mean ± SD: 4.23 ± 9.68), and 0.23 to 3.27 mgL-1 (mean ± SD: 1.10 ± 0.67). The obtained groundwater samples have pH values ranging from 5.9 to 7.1, which indicates a somewhat acidic to neutral character. Major cations have an average abundance that is as follows: Ca2+ > Mg2+ > Na+ > K+, while major anions have an average abundance that is as follows: HCO3- > Cl- > SO42- > NO3-; Ca2+ and HCO3- are the main cation and anion, respectively. The groundwater in the Rajarampur village was deemed unfit for drinking or irrigation based on analyses of water quality performed using the entropy water quality index. The Ca-HCO3 type of water, in which Ca2+ and HCO3- are the main positive ions and negative ions, is suggested by the Piper tri-linear diagram. It was discovered that silicate weathering regulates the hydro-geochemical activities in groundwater using a bi-variate examination of several hydro-chemical variables. Four major clusters were observed for the water sample. According to reductive dissolution processes and principal component analysis, the arsenic in groundwater is geogenic in origin. Arsenic is discharged from sediment to groundwater by reductive dissolution of FeOOH and MnOOH, as shown by the modest connection between As, Fe, and Mn. The United Nations Environmental Protection Agency's (USEPA) suggested value for probable cancer risk assessment was 10-6, however the probable cancer risk assessment found a higher value, indicating that the population in the study region was at high risk for cancer. Remedial measures for arsenic mitigation include removing arsenic from groundwater after it is extracted, searching for alternative aquifers, and implementing various water-supply technologies such as dugwells, deep tubewells, pond-sand filters, and rainwater harvesting systems.

Development of a standard evaluation method for microbial UV sensitivity using light-emitting diodes

Ultraviolet (UV) light is an effective disinfection method. In particular, UV light-emitting diodes (UV-LEDs) are expected to have many applications as light sources owing to their compact form factor and wide range of choices of wavelengths. However, the UV sensitivity of microorganisms for each UV wavelength has not been evaluated comprehensively because standard experimental conditions based on LED characteristics have not been established. Therefore, it is necessary to establish a standard evaluation method based on LED characteristics. Here, we developed a new UV-LED device based on strictly controlled irradiation conditions using LEDs for each wavelength (250-365 nm), checked the validity of the device characteristics and evaluated the UV sensitivity of Escherichia coli using this new evaluation method. For this new device, we considered accurate irradiance, accurate spectra, irradiance uniformity, accurate dose, beam angle, surrounding material reflections, and sample condition. From our results, the following UV irradiation conditions were established as standard: 1 mW/cm2 irradiance, bacterial solution with absorbance value of A600 = 0.5 diluted 10 times solution, solution volume of 1 mL, working distance (WD) of 100 mm. In order to compare the effects of irradiation under uniform conditions on inactivation of microorganisms, we assessed inactivation effect of E. coli by LED irradiation at each wavelength using the U280 LED as a standard wavelength. The inactivation effect for U280 LED irradiation was -0.95 ± 0.21 log at a dose of 4 mJ/cm2. Under this condition of dose, our results showed a high wavelength dependence of the inactivation effect at each UV wavelength peaking at 267 nm. Our study showed that this irradiation system was validated for the standard UV irradiation system and could be contributed to the establishment of food and water hygiene control methods and the development of equipment for the prevention of infectious diseases.

Facile synthesis of carbon quantum dot/silver nanocomposite and its antimicrobial, catalytic and sensing applications

Environmentally benign synthesis of nanocomposite, a pivotal facet of nanotechnology, and gaining prominence due to the increasing demand for facile, sustainable, and safe synthesis methods. The present research reports an facile/cost-effective method for the preparation of carbon dots (CDs) and carbon dot silver nanocomposites ( CD@AgNCs) via a hydrothermal treatment of peanut shells. The well-dispersed and spherical CDs with an average diameter of 5-6 nm were obtained and further employed for the preparation of CD@AgNCs. The formation of CD@AgNCs. was confirmed by optical and microscopic studies and ared shift in the λmax from 277 nm (CDs) to 450 nm (CD@AgNCs) with a size range of 30-40 nm was observed. The synthesized CD@AgNCs exhibit excellent catalytic potency for the reduction of 4-nitrophenol to 4-aminophenol, and also displaying a unique interaction and sensing ability towards heavy metal ions (Hg2+), causing a pronounced change in color from reddish-brown to transparent with limit of detection (LOD) of 23.47 ppm. Also, the prepared composite exhibit efficient antimicrobial potential against gram-negative (Escherichia coli) bacteria. Consequently, this study delves into a unified effective remediation platform with the integration of catalysis, sensing, and antimicrobial potentials.

Integration of N, P-doped carbon quantum dots with hydrogel as a solid-phase fluorescent probe for adsorption and detection of Fe3

In this work, a novel nitrogen-phosphorus co-doped carbon quantum dots (N, P-CQDs) hydrogel was developed utilizing the as-synthesized N, P-CQDs and acrylamide (AM) with the existence of ammonium persulfate and N, N'-methylene bisacrylamide (N-MBA). In consistent with pure N, P-CQDs, the N, P-CQDs hydrogel also shows a dramatic fluorescence property with maximum emission wavelength of 440 nm, which can also be quenched after adsorbing iron ions (Fe3+). When the concentration of Fe3+is 0-6 mmol l-1, a better linear relationship between Fe3+concentration and the fluorescence intensities can be easily obtained. Additionally, the N, P-CQDs hydrogel exhibits better recyclability. This confirms that the N, P-CQDs hydrogel can be used for adsorbing and detecting Fe3+in aqueous with on-off-on mode. The fluorescence quenching mainly involves three procedures including the adsorption of Fe3+by hydrogel, integration of Fe3+with N, P-CQDs and the transportation of conjugate electrons in N, P-CQDs to the vacant orbits of Fe3+and the adsorption process follows a pseudo-second-order kinetic model confirmed in the Freundlich isotherm model. In conclusion, this work provides a novel route for synchronously removing and detecting the metal ions in aqueous by integrating N, P-CQDs with hydrogel with better recyclability.

Identification of novel glucocerebrosidase chaperone for potential treatment of Parkinson's disease: An approach using in silico virtual screening, molecular docking and molecular dynamics, and in vitro studies

Glucocerebrosidase (GCase), a GBA1 gene-encoded lysosomal enzyme, is a risk factor for Parkinson's disease (PD). Chaperones that increase GCase activity can potentially be disease-modifying agents in PD. To date, none of the registered treatments has demonstrated disease-modifying effects. Thus, chaperones for GCase were identified using in-silico virtual screening, molecular property filtering, and molecular dynamics and validated by circular dichroism, FT-IR, and Raman spectroscopies. In-vitro enzyme kinetics, thermal denaturation assay (TDA), and cell-line model were used to test their potential for GCase In-silico investigation revealed four compounds as candidate chaperones with adequate brain penetrability and binding energy (BE). Of them, GC466 showed ideal chaperoning characteristics, including potent BE -8.92 ± 0.68 Kcal/mol and binding affinity (K_i) 0.64 ± 0.12 μM against rGCase (Asp146, Phe265, and His329 residues) at pH 7.0 than at 4.5 (BE: -5.06 Kcal/mol, K_i: not found). Spectroscopic results confirmed the stability of GCase by GC466. TDA determined its chaperoning behavior, signified by improved rGCase thermal stabilization with stabilization ratio of 10.20 at 10 μM. In addition, it demonstrated GCase restorative, neurorestorative, and ROS scavenging activity in 6-OHDA treated cell-line model. Therefore, the present study may offer a novel chaperone with the potential to be a disease-modifying agent for PD.

Bio-photoelectrochemical degradation, and photocatalysis process by the fabrication of copper oxide/zinc cadmium sulfide heterojunction nanocomposites: Mechanism, microbial community and antifungal analysis

In this work, the fabrication of the CuO on ZnCdS as a heterojunction nanocomposites were conducted by hydrothermal method and the synthesis method was confirmed by the XRD, XPS, EDS, UV-vis spectrum analysis. The CuO/ZnCdS was used as a photocathode in the bio-photoelectrochemical system (BPES) for tetracycline (TC) degradation under solar irradiation. The CuO/ZnCdS photocathode indicated substantial photocatalytic efficiency for TC degradation, due to the fast separation and transfer of photogenerated carriers. The ESR test evaluates the mechanism of degradation, and shows that ·OH, and ·O₂^- were contributed to TC degradation. The TC degradation was 1.59 times higher than the unilluminated process (98.72% vs 61.71). The photocatalysis test shows that the TC was degraded about 90.5% in 1.5 h. Then, the synthesized CuO/ZnCdS nanocomposites were studied for the biological application such as antifungal activities. CuO/ZnCdS nanocomposites depicted substantial antimicrobial activity versus Candida-albicans by in vitro process. Therefore, this study suggests the novel system for the antibiotics degradation, and as antifungal application.

Strong anti-viral nano biocide based on Ag/ZnO modified by amodiaquine as an antibacterial and antiviral composite

In this paper, we synthesized Ag/ZnO composite colloidal nanoparticles and the surface of nanoparticles was improved by amodiaquine ligand. The synthesized nanoparticles were characterized using the XRD diffraction pattern, FT-IR Spectroscopy, TEM image, and UV-Vis spectroscopy. The antibacterial, antifungal, and antiviral effects of the synthesized colloid were examined on E.coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Enterococcus hirae bacteria, and Candida Albicans and form spore aspergillus fungi, also influenza, herpes simplex, and covid 19 viruses. The results indicate more than 7 log removal of the bacteria, fungi, and viruses by synthesized colloid with a concentration of 15 μg/L (Ag)/50 µg/ml (ZnO). This removal for covid 19 virus is from 3.2 × 10⁸ numbers to 21 viruses within 30 s. Also, irritation and toxicity tests of the synthesized colloid show harmless effects on human cells and tissues. These colloidal nanoparticles were used as mouthwash solution and their clinical tests were done on 500 people infected by the coronavirus. The results indicate that by washing their mouth and nose three times on day all patients got healthy at different times depending on the depth of the disease. Almost all people with no signs of infection and using this solution as a mouthwash didn't infect by the virus during the study.

High efficiency of Ag0 decorated Cu2MoO4 nanoparticles for heterogeneous photocatalytic activation, bactericidal system, and detection of glucose from blood sample

The novel Ag0/Cu2MoO4 nanoparticles was simply synthesized via chemical method. Ag/Cu2MoO4 nanoparticles was characterized by FESEM image, XRD curve, UV-vis spectroscopy, BET analysis, and XPS spectrum. XRD pattern depicts that the cubic crystalline phase of particles. The band gap of Ag/Cu2MoO4 nanoparticles was achieved to 2.04 eV, which that depicted the best activity under visible light irradiation. Ag/Cu2MoO4 nanoparticles exhibits 99.74% degradation under light and persulfate ion which was higher response than Cu2MoO4 nanoparticles (83.56%) under this condition. The scavenging test indicates the important reactive species in removal process were •OH, and •SO4-. The Ag/Cu2MoO4 nanoparticles was indicated highly photo-stability for the MG degradation after 5th cycle. Ag/Cu2MoO4 exhibits substantial antibacterial properties against P. aeruginosa and S. pneumoniae. Moreover, Ag/Cu2MoO4 nanoparticles was experimented to peroxidase-like performance for the colorimetric detection of glucose with the Limit of Detection about 52.23 nM.

Quick and sensitive colorimetric detection of amino acid with functionalized-silver/copper nanoparticles in the presence of cross linker, and bacteria detection by using DNA-template nanoparticles as peroxidase activity

In this project, poly (citric acid) (PCA) functionalized on nano Ag/Cu was synthesized by chemical analysis method. The nano probe was applied to detection of cysteine by using the magnesium (II) ions as a cross linker. The characterization of Ag/Cu/PCA nano probe was studied by using the UV-visible, morphological microscopy, dynamic light scattering, and zeta potential analyzer. The zeta potential and size of Ag/Cu/PCA were -38.0 mV and 18.0 nm, respectively. The prepared nano probe shows rapid response for detection of cysteine. The detection limit of Ag/Cu/PCA nano probe was 0.07 nM. Additional, the Ag/Cu/PCA nanoparticles was applied to cysteine detection from real samples in the presence of amino acids compounds. Rapidly and sensitive determination of Streptococcus pneumoniae is substantial for food safety and human health. The DNA-Ag/Cu/PCA were prepared as a template in chemical method and experimented as a bio-receptor for the cell bacteria detection as peroxidase-like catalytic process. The DNA-Ag/Cu/PCA nano probe shows a linear dynamic concertation range of Streptococcus pneumoniae via detection limit about 65 CFU/mL. The project presents that the DNA-Ag/Cu/PCA could detect the biological and bacterial samples via high accuracy.

Fabrication of Cu2MoS4 decorated WO3 nano heterojunction embedded on chitosan: Robust photocatalytic efficiency, antibacterial performance, and bacteria detection by peroxidase activity

In this study, the Cu₂MoS₄/WO₃ supported on chitosan was prepared by precipitation method, and applied to photocatalyst, antibacterial agent and biosensor. The presence of WO₃ and Cu₂MoS₄ crystals were confirmed by XRD analysis. The elemental information was investigated by EDS. FTIR spectra shows the presence of chitosan in nanocomposites. The as-synthesized Cu₂MoS₄/WO₃/Chitosan nanocomposites has a bandgap of 2.18 eV and it is effective for visible light condition. The average particle size of the Cu₂MoS₄/WO₃/Chitosan is 71 nm. The photocatalysis activity Cu₂MoS₄/WO₃/Chitosan was higher than Cu₂MoS₄ or WO₃.The Cu₂MoS₄/WO₃/Chitosan nanocomposites shows the highest efficiency (100%) in photocatalysis degradation of dye under visible light irradiation in 80 min. The •O^2- plays a main role in degradation process. The as-synthesized Cu₂MoS₄/WO₃/Chitosan nanocomposites depicted the antibacterial activity toward G+/- bacteria. Determination of enterococcus faecalis is important for human health. The DNA template was used to the Cu₂MoS₄/WO₃/Chitosan nanocomposites and applied in detection of enterococcus faecalis by H₂O₂ and 3,3',5,5' -tetramethylbenzidine in peroxidase like activity. The detection limit of enterococcus faecalis by DNA-Cu₂MoS₄/WO₃/Chitosan in peroxidase-like catalysis was about 55 CFU/mL. Therefore, the Cu₂MoS₄/WO₃/Chitosan can be applied in the photocatalysis, bactericidal and peroxidase process.