Preparation of antibacterial film-based biopolymer embedded with vanadium oxide nanoparticles using one-pot laser ablation

Tuning the band gap, optical, mechanical, and electrical features of a bio-blend by Cr2O3/V2O5 nanofillers for optoelectronics and energy applications

This work presents a facile approach for controlling the optical and electrical parameters of a biopolymeric matrix for optoelectronics. Vanadium oxide (V2O5) and chromium oxide (Cr2O3) nanoparticles (NPs) were prepared and incorporated into the carboxymethylcellulose/polyethylene glycol (CMC/PEG) blend by simple chemical techniques. Transmission electron microscopy (HR-TEM), and X-ray diffraction (XRD) data showed that V2O5 and Cr2O3 exhibited spherical shapes with sizes in the range of 40-50 nm and 10-20 nm, respectively. In addition, the blend's degree of crystallinity was sensitive to the V2O5 and Cr2O3 doping ratios. The scanning electron microscopy (FE-SEM) and the elemental chemical analysis (EDAX) used to study the filler distribution inside the blend, and confirmed the existence of both V and Cr in the matrix. Fourier transform infrared (FTIR) spectroscopy showed that the dopants significantly affected the blend reactive (C-O-C, OH, and C=O) groups. The stress-strain curves illustrated the reinforcing effect of the dopants up to 1.0 wt\% Cr2O3/V. The transmittance and absorption index spectra in the visible-IR wavelengths decreased with increasing filler content. Utilizing Tauc's relation and (optical) dielectric loss, the direct (indirect) band gap narrowed from 5.6 (4.5) eV to 4.7 (3.05) eV at 1.0   wt\% Cr2O3/V. All films have an index of refraction in the range of 1.93-2.17. AC conductivity was improved with increasing filler content and temperature. The energy density at 50 °C is in the range of 1-3 J/m3. The influence of V2O5 and Cr2O3 content on the optical conductivity, dielectric constant, loss, and dielectric modulus of CMC/PEG was reported. These enhancements in electrical and optical properties, along with the potential for band gap engineering, offer promising prospects for advanced applications in optoelectronics and energy-related fields.

Biodegradable film based on barley sprout powder/pectin modified with quercetin and V2O5 nanoparticles: Investigation of physicochemical and structural properties

In this study, barley sprout powder/pectin (BS/Pec) composite film was prepared. Quercetin (Qu) and vanadium oxide (V2O5) nanoparticles were used to improve the physicochemical and structural characteristics of the film. The structural, physicochemical and thermal properties of the films were investigated by various techniques such as TGA, SEM, XRD, FTIR, texture analysis, etc. The thickness and tensile strength of the films increased from 120 μm to 2.4 MPa to 220 μm and 6 MPa respectively with the increase of V2O5 nanoparticles and quercetin pigment. Nanoparticles of V2O5 and quercetin decreased the moisture content of the film from 50% to 20%. Quercetin had little effect in reducing water vapor permeability (WVP), but V2O5 nanoparticles had a significant effect in reducing WVP. The pure BS/Pec film had almost 30% antioxidant properties, which increased to 81% with the increase of quercetin. Adding quercetin and V2O5 nanoparticles to the film increased the antimicrobial properties of the film against both Escherichia coli and Staphylococcus aureus bacteria. The SEM images showed the inhomogeneous surface of the BS/Pec film caused by BS powder fibers. The interactions between the components of the films (electrostatic type) was confirmed by FTIR results. The degradation temperature of the overall structure of the film in the presence of nanoparticles indicated the positive effect of nanoparticles in increasing the thermal resistance of the film. Investigating the crystal structure of the film showed that the BS/Pec film has an amorphous/crystalline or semi-crystalline structure. Considering that the prepared film has good mechanical properties and as well as antioxidant/antimicrobial properties, this film as an active composite can be used in food products packaging.

Green Synthesis of ZnO and V-Doped ZnO Nanoparticles Using Vinca rosea Plant Leaf for Biomedical Applications

The present work focused on the synthesis of Vinca rosea leaf extract derived ZnO and vanadium-doped ZnO nanoparticles (V-ZnO NPs). The chemical composition, structural, and morphology of ZnO and vanadium-doped ZnO NPs were examined by FTIR, XRD, and SEM-EDX. The FTIR confirmed the presence of functional groups corresponding to ZnO and vanadium-doped ZnO NPs. SEM-EDX clearly indicated the morphology of synthesised NPs; the hexagonal crystal of NPs was confirmed from XRD. In addition, the cytotoxic effect of ZnO and V-ZnO NPs was estimated against the breast cancer (MCF-7) cell line. From the assay, Vinca rosea (V. rosea) capped ZnO NPs have shown improved cytotoxic activity than that of Vinca rosea capped V-ZnO NPs. ZnO and vanadium-doped ZnO NPs showed the strongest antibacterial activity against Enterococcus, Escherichia coli, Candida albicans, and Aspergillus niger. The α-amylase inhibition assays demonstrated antidiabetic activity of synthesised NPs. From the assay test, results obtained Vinca rosea capped ZnO nanoparticles prepared using the green approach showed high effective antioxidant, antidiabetic activity, and anticancer activity than vanadium-doped ZnO NPs.

Preparing metallic bulk samples for transmission electron microscopy analysis via laser ablation in an acidic liquid

The laser ablation process has been presented as a state-of-the-art and robust method for eliminating surface layers of metallic bulk materials on the micro/nanoscale with considerable accuracy and speed. These capabilities make it an ideal instrument for the primary step of metallic bulk sample preparation for transmission electron microscopy (TEM) analysis with minimal damage to the crystal structure of the sample. This work prepared a pure aluminum plate by fiber laser scanning immersed in a 5 % perchloric acid and 95 % ethanol (by volume) solution. The laser ablation in an acidic liquid condition was used in the chemical etching process, to prevent oxidation, minimize the heat-affected region, and induce crystalline defects. For this purpose, a continuous wave fiber laser with a power of 100 W, a wavelength of 1064 nm, and a focusing distance of 305 mm was applied. The TEM analysis for the as-prepared sample by the laser ablation process was compared to the standard jet electro-polishing method in the same solution. The results showed that crystal structure variations such as grain size and lattice defects did not occur in the aluminum sample due to the thermal effects of the laser ablation process. The average size of the grains and zone axis were about 600-800 nm and z = [011], respectively, in as-prepared samples by both methods; In addition, very few dislocations were observed in the grain boundaries and inside the grains. Therefore, based on the obtained results, laser ablation could be considered an eco-friendly, comfortable, fast, and cost-effective method with a small volume of chemicals used, compared to the standard jet electro-polishing method for the TEM preparation of the metallic bulk samples.

Effects of Nd2O3 Nanoparticles on the Structural Characteristics and Dielectric Properties of PVA Polymeric Films

Polyvinyl alcohol (PVA) and Neodymium (III) oxide (Nd2O3) were combined to synthesized flexible innovative PVA/Nd2O3 polymer composite samples utilizing a solution casting approach for use in dielectric devices. The XRD, FTIR, and SEM methods are all investigated to characterize the composite films. In a frequency of 50 Hz to 5 MHz, the effects of additive Nd2O3 on the dielectric behavior of PVA were recorded. The PVA/Nd2O3 composite films were successfully fabricated, as shown by XRD and infrared spectroscopy. The scanning microscopy pictures showed that the Nd2O3 was loaded and distributed uniformly throughout the PVA. After the incorporation of Nd2O3, the composite PVA/Nd2O3 has a conductivity of 6.82 × 10-9 S·cm-1, while the PVA has a conductivity of 0.82 × 10-9 S·cm-1. Another improvement is the decrease in the relaxation time from 14.2 × 10-5 s for PVA to 6.35 × 10-5 s for PVA/Nd2O3, and an increase in the dielectric constant of 0.237 for PVA to 0.484 at a frequency of 100 Hz. The results showed that the composite samples have considerable changes as flexible films in different applications, including batteries and electronic circuits.

Bio-based antimicrobial food packaging films based on hydroxypropyl starch/polyvinyl alcohol loaded with the biosynthesized zinc oxide nanoparticles

In the last decades, bio-based active food packaging materials have received much attention. It is known that the utilization of traditional materials for food packaging applications lack some critical characteristics such as resistance to the harmful microbes that cause a damage to the preserved foods. Therefore, the current study aimed to find an alternative packaging films comprises an efficient biopolymers. This research work was designed to prepare film mats using hydroxypropyl starch (HPS), polyvinyl alcohol (PVA), palmitic acid (PA) and biosynthesized zinc oxide nanoparticles (ZnONPs). The fabricated films were coded as 1H, 2H, 3H and 4H based on the utilized concentration of ZnONPs. The biosynthesized ZnONPs and the bio-based films loaded with ZnONPs were characterized. The results revealed that ZnONPs exhibited nearly spherical shape and size ∼40 nm. The surface structure of the produced bioactive packaging films exhibited smooth with homogeneous features, excellent mechanical and thermal stability properties. The prepared bioactive packaging film loaded with ZnONPs (4H) exhibited superior antibacterial activity among other films against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 with inhibition zones 15.1 ± 0.76 and 12.1 ± 0.71 mm respectively. Correspondingly, packing film 4H exhibited potential antifungal activity toward Aspergillus niger RCMB 02724, A. flavus RCMB 02782, Penicillium expansum IMI 89372 and Fusarium oxysporum RCMB 001004 with inhibition zones (16 ± 1.0, 22 ± 0.90, 18.0 ± 1.1 and12.3 ± 0.57 mm respectively). Moreover, all prepared films did not show cytotoxicity on the normal cell line (Wi38) and recorded biodegradability properties that reached around 85 % after four weeks in soil. Based on these results, the antimicrobial films comprising HPS/PVA and loaded with the biosynthesized ZnONPs can be considered as a suitable film for food packaging purposes.

Modification on antibacterial activity of PVC/PVDF blend filled with CuO NPs using laser ablation technique

Nanocomposite of polyvinyl chloride (PVC)/polyvinylidene fluoride (PVDF) have been in situ synthesized. Copper oxide nanoparticles (CuONPs) have been prepared via using the laser ablation technique. Nanoparticles were added to the blend. The properties of the blend were studied before and after adding CuONPs. These properties were characterized by different techniques. Antimicrobial activity of the prepared nanocomposite film was investigated. FTIR data show vibrational spectral bands and the shift of the bands is related to the interaction and the complexation that occurs between blend and nanoparticles. Structural properties and crystallinity of the samples were investigated using XRD diffraction. XRD results illustrated the effect of CuONPs at two new peaks 2θ = 26.25º and 38.41º. These results confirmed the interaction CuO NPs and PVDF/PVC matrix. UV–Visible analyses confirmed the existing of copper oxide nanoparticles and were also used for determining the optical absorption edge. The absorption edges have been obtained at 430–520 nm for all of the doping films. The obtained values for indirect and direct bandgaps were reduced by raising the nanoparticles because of the presence of charge transfer between PVC/PVDF and CuONPs. SEM images illustrateed the presence of CuONPs on the surface of the blend and the morphology changes which occurred to the blend. The antibacterial activity for the nanocomposite proved the antimicrobial effect of copper oxide nanoparticles. The prepared PVC/PVDF/CuONPs are potentially suggesting to be applied for biomedical applications.

Synthesis of Nanocomposites of V₂O5©Selenium Nanoparticles and Multiwalled Carbon Nanotubes for Antimicrobial Activity

The authors report the preparation of the nanocomposite comprising of vanadium pentoxide (V₂O₅) and selenium (Se) nanoparticles and functionalized multiwalled carbon nanotubes (MWCNTs) (V₂O₅@Se NPs/MWCNTs). Since Se NPs possesses extraordinary physicochemical properties including larger surface area with higher adsorption capacity, V₂O₅ NPs were adsorbed onto Se NPs surface through physisorption process (designated as V₂O₅@Se NPs). The nanocomposite synthesized hydrothermally was evaluated for its antimicrobial activity. The morphology and microstructure of the nanocomposite were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis, respectively. Fourier transform infrared spectroscopy (FTIR) and UV-Visible spectroscopy (UV-Vis) were employed to analyze the spectral properties of nanocomposite. The microbicidal efficacy of nanocomposite was tested against Gram-negative (G-)ZGram-positive (G+) bacteria and fungus. This is the first report on the synthesis of V₂O₅@Se NPs/MWCNTs nanocomposites by chemical method that showed microbicidal effect on micro-organisms. The thiol (-SH) units facilitates the enrichment of V₂O₅@Se NPs onto MWCNTs surface. Ultimately, it reflects on the significant antimicrobial activity of V₂O₅@Se NPs/MWCNTs.

Emerging Trends in Nanomaterials for Antibacterial Applications

Around the globe, surges of bacterial diseases are causing serious health threats and related concerns. Recently, the metal ion release and photodynamic and photothermal effects of nanomaterials were demonstrated to have substantial efficiency in eliminating resistance and surges of bacteria. Nanomaterials with characteristics such as surface plasmonic resonance, photocatalysis, structural complexities, and optical features have been utilized to control metal ion release, generate reactive oxygen species, and produce heat for antibacterial applications. The superior characteristics of nanomaterials present an opportunity to explore and enhance their antibacterial activities leading to clinical applications. In this review, we comprehensively list three different antibacterial mechanisms of metal ion release, photodynamic therapy, and photothermal therapy based on nanomaterials. These three different antibacterial mechanisms are divided into their respective subgroups in accordance with recent achievements, showcasing prospective challenges and opportunities in clinical, environmental, and related fields.

A Comprehensive Review of Microneedles: Types, Materials, Processes, Characterizations and Applications

Drug delivery through the skin offers many advantages such as avoidance of hepatic first-pass metabolism, maintenance of steady plasma concentration, safety, and compliance over oral or parenteral pathways. However, the biggest challenge for transdermal delivery is that only a limited number of potent drugs with ideal physicochemical properties can passively diffuse and intercellularly permeate through skin barriers and achieve therapeutic concentration by this route. Significant efforts have been made toward the development of approaches to enhance transdermal permeation of the drugs. Among them, microneedles represent one of the microscale physical enhancement methods that greatly expand the spectrum of drugs for transdermal and intradermal delivery. Microneedles typically measure 0.1-1 mm in length. In this review, microneedle materials, fabrication routes, characterization techniques, and applications for transdermal delivery are discussed. A variety of materials such as silicon, stainless steel, and polymers have been used to fabricate solid, coated, hollow, or dissolvable microneedles. Their implications for transdermal drug delivery have been discussed extensively. However, there remain challenges with sustained delivery, efficacy, cost-effective fabrication, and large-scale manufacturing. This review discusses different modes of characterization and the gaps in manufacturing technologies associated with microneedles. This review also discusses their potential impact on drug delivery, vaccine delivery, disease diagnostic, and cosmetics applications.