Dual UV irradiation-based metal oxide nanoparticles for enhanced antimicrobial activity in Escherichia coli and M13 bacteriophage

Enhanced antimicrobial efficacy of biogenic ZnO nanoparticles through UV-B activation: A novel approach for textile garment

Zinc oxide nanoparticles (ZnO NP) are characterized by novel properties which have been attracting the attention of different lines of research due to their wide applicability. Obtaining this nanomaterial is strongly linked to biogenic synthesis methods, which have also been developed in this research, using Coriandrum sativum extract as a reducing agent. ZnO NPs have been properly characterized by techniques to evaluate their morphology by transmission electron microscopy (TEM) and elemental analysis by EDX. The evaluation of the antimicrobial and antifungal effects is linked to the use of a system provided by "locker sanitizer" equipment, which has been designed and built as part of this research, and is intended to treat textile garments by nebulizing the ZnO NP colloid (99.08 μg/mL) + UV-B, water + UV-B, and UV-B only, and also to evaluate the influence of the treatment time for 1, 2 and 3 min. In this sense, it is known that the nanomaterial used shows a better response to UV light because more hydroxyl radicals are produced, leading to a higher reaction rate, which results in greater efficiency in inhibitory processes. The results show that the use of the locker sanitizer is more efficient when using ZnO NP + UV-B light since it achieved 100 % growth inhibition against E. coli, C. albicans, and A. brasiliensis, and >99 % against S. aureus, after 3 min of treatment.

Review on Additives in Hydrogels for 3D Bioprinting of Regenerative Medicine: From Mechanism to Methodology

The regeneration of biological tissues in medicine is challenging, and 3D bioprinting offers an innovative way to create functional multicellular tissues. One common way in bioprinting is bioink, which is one type of the cell-loaded hydrogel. For clinical application, however, the bioprinting still suffers from satisfactory performance, e.g., in vascularization, effective antibacterial, immunomodulation, and regulation of collagen deposition. Many studies incorporated different bioactive materials into the 3D-printed scaffolds to optimize the bioprinting. Here, we reviewed a variety of additives added to the 3D bioprinting hydrogel. The underlying mechanisms and methodology for biological regeneration are important and will provide a useful basis for future research.

Preparation of zinc oxide nanoparticles using laser-ablation technique: Retinal epithelial cell (ARPE-19) biocompatibility and antimicrobial activity when activated with femtosecond laser

The unusual physical, chemical, and biological features of nanoparticles have sparked considerable attention in the ophthalmological applications. This study reports the synthesis and characterization of zinc oxide nanoparticles (ZnONPs) using laser-ablation at 100 mJ with different ablation times. The synthesized ZnONPs were spherical with an average size of 10.2 nm or 9.8 nm for laser ablation times of 20 and 30 min, respectively. The ZnONPs were screened for their antimicrobial activity against ophthalmological bacteria, methicillin-resistant S. aureus (MRSA) and Pseudomonas aeruginosa. The significant decrease in bacterial growth was observed after treatment with ZnONPs in combination with 400 nm femtosecond laser irradiation. ZnONPs were investigated for their antioxidant activity and biocompatibility towards retinal epithelial cells (ARPE-19). ZnONPs showed moderate antioxidant and free radical scavenging activity. ZnONPs prepared with an ablation time of 20 min were safer and more biocompatible than those prepared with an ablation time of 30 min, which were toxic to ARPE-19 cells with LC₅₀ (11.3 μg/mL) and LC₉₀ (18.3 μg/mL). In this study, laser ablation technique was used to create ZnONPs, and it was proposed that ZnONPs could have laser-activated antimicrobial activity for ophthalmological applications.

Multiscale Metal Oxide Particles to Enhance Photocatalytic Antimicrobial Activity against Escherichia coli and M13 Bacteriophage under Dual Ultraviolet Irradiation

Antimicrobial activity of multiscale metal oxide (MO) particles against Escherichia coli (E. coli) and M13 bacteriophage (phage) was investigated under dual ultraviolet (UV) irradiation. Zinc oxide (ZnO), magnesium oxide (MgO), cuprous oxide (Cu₂O), and cupric oxide (CuO) were selected as photocatalytic antimicrobials in MO particles. Physicochemical properties including morphology, particle size/particle size distribution, atomic composition, crystallinity, and porosity were evaluated. Under UV-A and UV-C irradiation with differential UV-C intensities, the antimicrobial activity of MO particles was monitored in E. coli and phage. MO particles had nano-, micro- and nano- to microscale sizes with irregular shapes, composed of atoms as ratios of chemical formulae and presented crystallinity as pure materials. They had wide-range specific surface area levels of 0.40–46.34 m²/g. MO particles themselves showed antibacterial activity against E. coli, which was the highest among the ZnO particles. However, no viral inactivation by MO particles occurred in phage. Under dual UV irradiation, multiscale ZnO and CuO particles had superior antimicrobial activities against E. coli and phage, as mixtures of nano- and microparticles for enhanced photocatalytic antimicrobials. The results showed that the dual UV-multiscale MO particle hybrids exhibit enhanced antibiotic potentials. It can also be applied as a next-generation antibiotic tool in industrial and clinical fields.

Antimicrobial activity and biocompatibility of the mixture of mineral trioxide aggregate and nitric oxide-releasing compound

Background/purpose

Antimicrobial activity and biocompatibility of root canal sealer are related to the success of endodontic treatments. This study investigated the efficacy of mixture of mineral trioxide aggregate (MTA) and a NO-releasing compound for the antimicrobial activity, biocompatibility, and physical properties.

Materials and methods

MTA was mixed with diethylenetriamine-NO (MTA-NO), and the extracts from MTA and the MTA-NO mixture before and after setting was obtained were investigated the antimicrobial activity against Enterococcus faecalis and Porphyromonas endodontalis. After setting MTA and MTA-NO, pulp cell was incubated in the presence of MTA and MTA-NO disk using Transwell® cell culture insert, and the proliferation assay and mineralization-stimulated factors of the cells were analyzed by MTT assay and real-time RT-PCR, respectively. The physical properties of MTA and the MTA-NO mixture, such as surface hardness and flowability was also analyzed.

Results

The MTA-NO mixture showed stronger antimicrobial activity against E. faecalis and P. endodontalis than that by MTA. Both MTA and MTA-NO mixture increase the ratio of cell proliferation and induced the expression of alkaline phosphatase, collagen type I, osteocalcin, and osteopontin. Moreover, the induction of gene expression by MTA-NO mixture was higher than that by MTA alone. No significant difference was observed for surface hardness and flowability between MTA and MTA-NO mixture.

Conclusion

The addition of a NO-releasing compound to the endodontic treatment using MTA root canal sealer might reduce the risk of bacterial infection and help to regenerate the dental pulp tissue.

Zinkicide Is a ZnO-Based Nanoformulation with Bactericidal Activity against Liberibacter crescens in Batch Cultures and in Microfluidic Chambers Simulating Plant Vascular Systems

Phloem-limited bacterial "Candidatus Liberibacter" species are associated with incurable plant diseases worldwide. Antimicrobial treatments for these pathogens are challenging due to the difficulty of reaching the vascular tissue they occupy at bactericidal concentrations. Here, in vitro antimicrobial mechanisms of Zinkicide TMN110 (ZnK), a nonphytotoxic zinc oxide (ZnO)-based nanoformulation, were compared to those of bulk ZnO (b-ZnO) using as a model the only culturable species of the genus, Liberibacter crescens Minimum bactericidal concentration (MBC) determination and time-kill assays showed that ZnK has a bactericidal effect against L. crescens, whereas b-ZnO is bacteriostatic. When ZnK was used at the MBC (150 ppm), its antimicrobial mechanisms included an increase in Zn solubility, generation of intracellular reactive oxygen species, lipid peroxidation, and cell membrane disruption; all of these were of greater intensity than those of b-ZnO. Inhibition of biofilms, which are important during insect vector colonization, was stronger by ZnK than by b-ZnO at concentrations between 2.5 and 10 ppm in batch cultures; however, neither ZnK nor b-ZnO removed L. crescens preformed biofilms when applied between 100 and 400 ppm. In microfluidic chambers simulating source-to-sink phloem movement, ZnK significantly outperformed b-ZnO in Zn mobilization and bactericidal activity against L. crescens planktonic cells in sink reservoirs. In microfluidic chamber assays assessing antibiofilm activity, ZnK displayed a significantly enhanced bactericidal activity against L. crescens individual attached cells as well as preformed biofilms compared to that of b-ZnO. The superior mobility and antimicrobial activity of ZnK in microenvironments make this formulation a promising product to control plant diseases caused by "Candidatus Liberibacter" species and other plant vascular pathogens.IMPORTANCE "Candidatus Liberibacter" species are associated with incurable plant diseases that have caused billions of dollars of losses for United States and world agriculture. Chemical control of these pathogens is complicated, because their life cycle combines intracellular vascular stages in plant hosts with transmission by highly mobile insect vectors. To date, "Candidatus Liberibacter" species are mostly unculturable, except for Liberibacter crescens, a member of the genus that has been used as a model for in vitro assays. Here, we evaluated the potential of Zinkicide (ZnK) as an antimicrobial against "Candidatus Liberibacter" species in batch cultures and under flow conditions, using L. crescens as a biological model. ZnK displayed bactericidal activity against L. crescens in batch cultures and showed increased mobility and bactericidal activity in microfluidic devices resembling "Candidatus Liberibacter" species natural habitats. ZnK performance observed here against L. crescens makes this compound a promising candidate to control plant diseases caused by vascular pathogens.

Metal Oxide Nanoparticles as Biomedical Materials

The development of new nanomaterials with high biomedical performance and low toxicity is essential to obtain more efficient therapy and precise diagnostic tools and devices. Recently, scientists often face issues of balancing between positive therapeutic effects of metal oxide nanoparticles and their toxic side effects. In this review, considering metal oxide nanoparticles as important technological and biomedical materials, the authors provide a comprehensive review of researches on metal oxide nanoparticles, their nanoscale physicochemical properties, defining specific applications in the various fields of nanomedicine. Authors discuss the recent development of metal oxide nanoparticles that were employed as biomedical materials in tissue therapy, immunotherapy, diagnosis, dentistry, regenerative medicine, wound healing and biosensing platforms. Besides, their antimicrobial, antifungal, antiviral properties along with biotoxicology were debated in detail. The significant breakthroughs in the field of nanobiomedicine have emerged in areas and numbers predicting tremendous application potential and enormous market value for metal oxide nanoparticles.

Synthesis, Characterization, and Three-Dimensional Structure Generation of Zinc Oxide-Based Nanomedicine for Biomedical Applications

Zinc oxide (ZnO) nanoparticles have been studied as metal-based drugs that may be used for biomedical applications due to the fact of their biocompatibility. Their physicochemical properties, which depend on synthesis techniques involving physical, chemical, biological, and microfluidic reactor methods affect biological activity in vitro and in vivo. Advanced tool-based physicochemical characterization is required to identify the biological and toxicological effects of ZnO nanoparticles. These nanoparticles have variable morphologies and can be molded into three-dimensional structures to enhance their performance. Zinc oxide nanoparticles have shown therapeutic activity against cancer, diabetes, microbial infection, and inflammation. They have also shown the potential to aid in wound healing and can be used for imaging tools and sensors. In this review, we discuss the synthesis techniques, physicochemical characteristics, evaluation tools, techniques used to generate three-dimensional structures, and the various biomedical applications of ZnO nanoparticles.

Photocatalytic antibacterial application of zinc oxide nanoparticles and self-assembled networks under dual UV irradiation for enhanced disinfection

Background

Zinc oxide (ZnO) nanoparticles and their networks have been developed for use in various applications such as gas sensors and semiconductors.

Aim

In this study, their antibacterial activity against Escherichia coli under dual ultraviolet (UV) irradiation for disinfection was investigated.

Materials and methods

ZnO nanoparticles were synthesized and immobilized onto silicon (Si) wafers by self-assembly. The physicochemical properties and antibacterial activity of ZnO nanoparticles and their networks were evaluated. Gene ontology was analyzed and toxicity levels were also monitored.

Results

Synthesized ZnO nanoparticles were spherical nanocrystals (<100 nm; Zn, 47%; O, 53%) that formed macro–mesoporous three-dimensional nanostructures on Si wafers in a concentration-dependent manner. ZnO nanoparticles and their networks on Si wafers had an excellent antibacterial activity against E. coli under dual UV irradiation (>3log CFU/mL). Specifically, arrayed ZnO nanoparticle networks showed superior activity compared with free synthesized ZnO nanoparticles. Oxidative stress-responsive proteins in E. coli were identified and categorized, which indicated antibacterial activity. Synthesized ZnO nanoparticles were less cytotoxic in HaCaT with an IC50 of 6.632 mg/mL, but phototoxic in Balb/c 3T3.

Conclusion

The results suggested that ZnO nanoparticles and their networks can be promising photocatalytic antibiotics for use in next-generation disinfection systems. Their application could also be extended to industrial and clinical use as effective and safe photocatalytic antibiotics.