Zinc Oxide Nanoparticles Cytotoxicity and Release from Newly Formed PMMA-ZnO Nanocomposites Designed for Denture Bases

Zinc oxide nanoparticles prevent the onset of diabetic nephropathy by inhibiting multiple pathways associated with oxidative stress

BACKGROUND

Zinc deficiency is strongly correlated with prolonged diabetes mellitus and diabetic nephropathy (DN). Previously, glucose-lowering, insulinomimetic, and β-cell proliferative activities of zinc oxide nanoparticles (ZON) have been reported. Considering these pleiotropic effects, we hypothesized that ZON modulates multiple cellular pathways associated with necroptosis, inflammation, and renal fibrosis, which are involved in progressive loss of renal function.

AIM

This study evaluated the effect of ZON on renal function, leading to the alleviation of DN in streptozotocin (STZ)-induced type 1 diabetic Wistar rats and proposed a probable mechanism for its activity.

METHODS

Wistar rats (n = 6/group) were used as healthy controls, diabetic controls, diabetic rats treated with ZON (1, 3, and 10 mg/kg), and insulin controls. Urine and serum biochemical parameters, glomerular filtration rate (GFR), and renal histology were also evaluated. Cultured E11 podocytes were evaluated in vitro for markers of oxidative stress, proteins associated with the loss of renal function, and genes associated with renal damage.

KEY FINDINGS

STZ-treated rats receiving oral doses of ZON showed enhanced renal function, with no histological alterations in the kidney tissue. ZON inhibited the TGF-β/Samd3 pathway in renal fibrosis; blocked Ripk1/Ripk3/Mlkl mediated necroptosis and protected against hyperglycemia-induced pyroptosis. In E11 podocytes, ZON reduced oxidative stress under high glucose conditions and retained podocyte-specific proteins.

SIGNIFICANCE

A probable mechanism by which ZON prevents DN has been proposed, suggesting its use as a complementary therapeutic agent for the treatment of diabetic complications. To the best of our knowledge, this is the first study to demonstrate the in vitro effects of ZON in cultured podocytes.

Synthesis and characterization of mesoporous zinc oxide nanoparticles and evaluation of their biocompatibility in L929 fibroblasts

OBJECTIVES

This study aimed to synthesize and characterize mesoporous zinc oxide nanoparticles (ZnO NPs) and also to evaluate the cytotoxicity of mesoporous ZnO NPs on L929 mouse fibroblast cell lines using 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay.

MATERIALS AND METHODS

The synthesized mesoporous ZnO NPs were extensively characterized using X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectra (EDAX), Fourier-transform infrared spectroscopy (FTIR), and dynamic light scattering (DLS). The cytotoxicity of mesoporous ZnO NPs was assessed by MTT assay. The study groups for cytotoxicity assay were normal saline, 0.1% calcined mesoporous ZnO NP solution, 1% calcined mesoporous ZnO NP solution, 0.1% noncalcined mesoporous ZnO NP solution, 1% noncalcined mesoporous ZnO NP solution, 0.1% ZnO NP solution, 1% ZnO NP solution, 2% chlorhexidine, and phosphate-buffered saline (PBS). The percentages of mean ± standard deviation of viable cells were analyzed.

RESULTS

Characterization of mesoporous ZnO NPs revealed that all the particles were in a more or less spherical shape with a wide particle size distribution of 70-100 nm. TEM image showed the uniformed and aggregated ZnO NPs with a typical size of 10-15 nm. BET analysis showed a mesoporous structure for the prepared mesoporous ZnO NPs. According to the MTT assay, chlorhexidine had the lowest cell viability percentage. Cell viability percentages of 0.1% mesoporous ZnO NP solutions (calcined and noncalcined) were statistically, significantly higher than 0.1% ZnO NP solution (p < .05). Cell viability percentages of 0.1% calcined and noncalcined mesoporous ZnO NP solutions and 0.1% ZnO NP solution were statistically, significantly higher than the 1% solutions (p < .05).

CONCLUSION

Mesoporous ZnO NPs exhibited less cytotoxicity against L929 mouse fibroblast cell lines compared to CHX and ZnO NPs, hence are safe to use.

Local and systemic adverse effects of nanoparticles incorporated in dental materials- a critical review

Introduction

Nanotechnology is the science and engineering of nanoparticles whose dimensions range from 1 to 100 nm. Nanoparticles have special characteristics like increased surface area, high reactivity, and enhanced mechanical, thermal, and optical properties that make them attractive for use in dental applications. However, the use of nanoparticles in dental materials can have toxic effects on the human body. The objective of this paper is to discuss the toxic effects of various nanoparticles in dental materials, their adverse effect on human health, and measures to overcome such effects.

Objectives

Nanoparticles are used in the diagnosis, prevention, and treatment of oral diseases like dental caries, pulpo periodontal lesions, oral cancer, denture stomatitis, and candidiasis. Exposure to nanoparticles may occur to the dental professional, and the patient during procedures like restoration, finishing, and polishing. Such exposure to nanoparticles through inhalation, and ingestion causes toxic effects in the lungs, skin, brain, liver, and kidney. Proper risk assessment methods and preventive measures may help reduce these toxic effects to some extent.

Significance

Toxic effects of nanoparticles that are released during dental procedures, their route of exposure, and the concentration at which nanoparticles can induce toxic effects on the human body are discussed in detail in this review. The paper also aims to create awareness among dental professionals, students, and patients regarding nanoparticle exposure and its adverse effects, and methods to prevent and overcome these effects. Currently, it is ignored or taken lightly by the stakeholders and this review may throw light.

Development of alginate-based film incorporated with anthocyanins of red cabbage and zinc oxide nanoparticles as freshness indicator for prawns

The objective of this study was to develop pH-sensitive film indicators for intelligent food packaging by incorporating red cabbage anthocyanins (RCA) and zinc oxide nanoparticles (ZnO NPs) into an alginate (Alg) film, aiming to mitigate the risk of foodborne illnesses. The films were fabricated using a solvent-casting method and crosslinked with a calcium chloride (CaCl2) solution. Thorough evaluations of the films' physical, mechanical, and structural properties demonstrated significant improvements in elastic modulus and UV/vis light barrier characteristics, reduced water vapor permeability (WVP), and moisture content attributed to integrating RCA and ZnO NPs. The resulting film displayed discernible color changes when exposed to various pH buffer solutions and ammonia vapor, indicating heightened sensitivity to pH fluctuations due to the presence of ZnO NPs. Visual assessment using prawns as test specimens revealed a color shift from violet (indicating satisfactory condition) to blue-greenish (indicating spoilage), corroborated by colorimetric analysis. Moreover, the Alg/ZnO/RCA film exhibited antioxidant and antibacterial properties, demonstrated biodegradation activity, and showed no toxic effects on RSC96 cells, further underscoring its potential as an effective freshness indicator for food products.

XRD and cytotoxicity assay of submitted nanomaterial industrial samples in the Philippines

Distinct properties that nanomaterials possess compared to their bulk counterparts are attributed to their characteristic high surface area to volume ratios, and the prevalence of structure and shape effects at the nanoscale. However, these interesting properties are also accompanied by health hazards that are not seen in bulk materials. In the context of Philippine research and industry, the issue of nanosafety and the creation of nanotechnology guidelines have long been overlooked. This is of particular importance considering that nanotechnology research in the Philippines leans heavily towards medicinal and agricultural applications. In this study, nanomaterial samples from the industry submitted through the Philippine Industrial Technology Development Institute (ITDI) were analyzed using XRD and MTT cytotoxicity assay. XRD results show significant band broadening in the diffraction patterns of halloysite nanoclay, bentonite nanoparticles, silver nanoparticles, and CaCO3 nanoparticles, indicating that samples were in the nanometer range. The diffraction pattern of TiO2, however, did not exhibit band broadening, which may be due to the tendency of TiO2 nanoparticles to aggregate. Submitted samples were also assessed for their effect on cell viability using MTT cytotoxicity assay. Among these samples, only silver nanoparticles exhibited cytotoxicity to the AA8 cell line.

Antimicrobial efficacy of zinc oxide nanoparticle-coated aligners on Streptococcus mutans and Candidaalbicans

INTRODUCTION

This study aimed to assess the antimicrobial effect of zinc oxide (ZnO) nanocoating on aligners.

METHODS

Twenty-six samples of aligners were sputter-coated with ZnO nanoparticles and compared with 26 uncoated samples. The antimicrobial effect was assessed on Streptococcus mutans and Candida albicans. The thickness of the ZnO coating was standardized at 100 nm. The antimicrobial effect was evaluated for 7 days at the following time points: 6 hours, 12 hours, first day, second day, fourth day, and seventh day. Colony culture tests were performed for microbial evaluation.

RESULTS

ZnO-coated aligners showed significant antimicrobial efficacy against S mutans at all time points tested (P <0.001). The antimicrobial effect was observed up to 2 days after a decline. The activity against C albicans was minimal at all time points, and no statistical significance was observed (P >0.05).

CONCLUSIONS

ZnO-nanocoated aligners were effective against S mutans, with the maximum antibacterial effect observed until 2 days and lasting for 7 days. The effect against C albicans was minimal. ZnO-coated aligners appears to be a promising technique to facilitate antimicrobial efficacy against S mutans.

Green Synthesized Zinc Oxide Nanoparticles Using Moringa olifera Ethanolic Extract Lessens Acrylamide-Induced Testicular Damage, Apoptosis, and Steroidogenesis-Related Gene Dysregulation in Adult Rats

This study assessed the possible protective role of green synthesized zinc oxide nanoparticles using Moringa olifera leaf extract (MO-ZNPs) in acrylamide (ACR)-induced reproductive dysfunctions in male rats. ACR (20 mg/kg b.wt/day) and/or MO-ZNPs (10 mg/kg b.wt/day) were given orally by gastric gavage for 60 days. Then, sperm parameters; testicular enzymes; oxidative stress markers; reproductive hormones including testosterone, luteinizing hormone (LH)-estradiol, and follicle-stimulating hormone (FSH) concentration; testis histology; steroidogenesis-related gene expression; and apoptotic markers were examined. The findings revealed that MO-ZNPs significantly ameliorated the ACR-induced decline in the gonadosomatic index and altered the pituitary-gonadal axis, reflected by decreased serum testosterone and FSH with increased estradiol and LH, and sperm analysis disruption. Furthermore, a notable restoration of the tissue content of antioxidants (catalase and reduced glutathione) but depletion of malondialdehyde was evident in MO-ZNPs+ACR-treated rats compared to ACR-exposed ones. In addition, MO-ZNPs oral dosing markedly rescued the histopathological changes and apoptotic caspase-3 reactions in the testis resulting from ACR exposure. Furthermore, in MO-ZNPs+ACR-treated rats, ACR-induced downregulation of testicular steroidogenesis genes and proliferating cell nuclear antigen (PCNA) immune-expression were reversed. Conclusively, MO-ZNPs protected male rats from ACR-induced reproductive toxicity by suppressing oxidative injury and apoptosis while boosting steroidogenesis and sex hormones.

Effect of Zinc Oxide Incorporation on the Antibacterial, Physicochemical, and Mechanical Properties of Pit and Fissure Sealants

This study aimed to evaluate the antibacterial, physicochemical, and mechanical properties of pit and fissure sealants containing different weight percentages of zinc oxide nanoparticles (ZnO NPs). The following amounts of ZnO NPs were added to a commercially available pit and fissure sealant (BeautiSealant, Shofu, Japan) to prepare the experimental materials: 0 wt.% (commercial control (CC)), 0.5 wt.% (ZnO 0.5), 1 wt.% (ZnO 1.0), 2 wt.% (ZnO 2.0), and 4 wt.% (ZnO 4.0). The antibacterial effect against S. mutans was confirmed by counting the colony-forming units (CFUs) and observing live/dead bacteria. In addition, ion release, depth of cure, water sorption and solubility, and flexural strength tests were conducted. When compared with the CC, the experimental groups containing ZnO NPs showed zinc ion emission and significantly different CFUs (p < 0.05) with fewer live bacteria. ZnO NP addition reduced the depth of cure and water solubility and increased water sorption in comparison with the CC (p < 0.05). However, all groups showed similar flexural strength (p > 0.05). The pit and fissure sealants containing ZnO NPs exhibited antibacterial activity against S. mutans with no negative effects on physicochemical and mechanical properties, and thus, these sealants can be ideal secondary caries prevention material.

Phyto-assisted synthesis of zinc oxide nanoparticles for developing antibiofilm surface coatings on central venous catheters

Medical devices such as Central Venous Catheters (CVCs), are routinely used in intensive and critical care settings. In the present scenario, incidences of Catheter-Related Blood Stream Infections (CRBSIs) pose a serious challenge. Despite considerable advancements in the antimicrobial therapy and material design of CVCs, clinicians continue to struggle with infection-related complications. These complications are often due colonization of bacteria on the surface of the medical devices, termed as biofilms, leading to infections. Biofilm formation is recognized as a critical virulence trait rendering infections chronic and difficult to treat even with 1,000x, the minimum inhibitory concentration (MIC) of antibiotics. Therefore, non-antibiotic-based solutions that prevent bacterial adhesion on medical devices are warranted. In our study, we report a novel and simple method to synthesize zinc oxide (ZnO) nanoparticles using ethanolic plant extracts of Eupatorium odoratum. We investigated its physio-chemical characteristics using Field Emission- Scanning Electron Microscopy and Energy dispersive X-Ray analysis, X-Ray Diffraction (XRD), Photoluminescence Spectroscopy, UV-Visible and Diffuse Reflectance spectroscopy, and Dynamic Light Scattering characterization methods. Hexagonal phase with wurtzite structure was confirmed using XRD with particle size of ∼50 nm. ZnO nanoparticles showed a band gap 3.25 eV. Photoluminescence spectra showed prominent peak corresponding to defects formed in the synthesized ZnO nanoparticles. Clinically relevant bacterial strains, viz., Proteus aeruginosa PAO1, Escherichia coli MTCC 119 and Staphylococcus aureus MTCC 7443 were treated with different concentrations of ZnO NPs. A concentration dependent increase in killing efficacy was observed with 99.99% killing at 500 μg/mL. Further, we coated the commercial CVCs using green synthesized ZnO NPs and evaluated it is in vitro antibiofilm efficacy using previously optimized in situ continuous flow model. The hydrophilic functionalized interface of CVC prevents biofilm formation by P. aeruginosa, E. coli and S. aureus. Based on our findings, we propose ZnO nanoparticles as a promising non-antibiotic-based preventive solutions to reduce the risk of central venous catheter-associated infections.

Dimensions of Hybrid and Nanohybrid Mouthguards for Mixed Martial Arts Fighters-Evaluation of a New Method of Fabrication

Ethylene vinyl acetate mouthguards are the most often used custom protective intraoral appliances by combat sports practitioners. However, due to the difficulties in maintaining the hygiene of such mouthguards and thinning during fabrication, resulting in difficulty in predicting final dimensions, they may not be the optimal solution. The aim of this research was to evaluate an innovative method of mouthguard formation using intraoral modeling of the mouthguard pattern, hybrid acrylic material, and the addition of ZnO nanoparticles. Seventeen mouthguards patterns and 34 custom mouthguards were evaluated: 17 hybrid and 17 nanohybrid. A total of 1122 measurements were performed: each mouthguard and pattern was measured at 22 points. Statistical analyses were performed with the use of IBM^® SPSS^® Statistics 27.0.0 software (IBM, Armonk, NY USA). The mean thickness of the patterns and mouthguards at all labial areas of central incisors were between 4.65 and 4.80 mm. The thickness at the buccal surface of the first molar was between 3.71 and 4 mm, and at the occlusal surface between 3.40 and 3.56 mm in the cusp area. All measurements of hybrid and nanohybrid mouthguards were strongly and highly correlated with the measurements of the mouthguard patterns. Hybrid and nanohybrid mouthguards are an advantageous alternative to thermoformed custom appliances.

Composite Coating for the Food Industry Based on Fluoroplast and ZnO-NPs: Physical and Chemical Properties, Antibacterial and Antibiofilm Activity, Cytotoxicity

Bacterial contamination of meat products during its preparation at the enterprise is an important problem for the global food industry. Cutting boards are one of the main sources of infection. In order to solve this problem, the creation of mechanically stable coatings with antibacterial activity is one of the most promising strategies. For such a coating, we developed a composite material based on "liquid" Teflon and zinc oxide nanoparticles (ZnO-NPs). The nanoparticles obtained with laser ablation had a rod-like morphology, an average size of ~60 nm, and a ζ-potential of +30 mV. The polymer composite material was obtained by adding the ZnO-NPs to the polymer matrix at a concentration of 0.001-0.1% using the low-temperature technology developed by the research team. When applying a composite material to a surface with damage, the elimination of defects on a micrometer scale was observed. The effect of the composite material on the generation of reactive oxygen species (H₂O₂, •OH), 8-oxoguanine in DNA in vitro, and long-lived reactive protein species (LRPS) was evaluated. The composite coating increased the generation of all of the studied compounds by 50-200%. The effect depended on the concentration of added ZnO-NPs. The antibacterial and antibiofilm effects of the Teflon/ZnO NP coating against L. monocytogenes, S. aureus, P. aeruginosa, and S. typhimurium, as well as cytotoxicity against the primary culture of mouse fibroblasts, were studied. The conducted microbiological study showed that the fluoroplast/ZnO-NPs coating has a strong bacteriostatic effect against both Gram-positive and Gram-negative bacteria. In addition, the fluoroplast/ZnO-NPs composite material only showed potential cytotoxicity against primary mammalian cell culture at a concentration of 0.1%. Thus, a composite material has been obtained, the use of which may be promising for the creation of antibacterial coatings in the meat processing industry.

Color Stability of Zinc Oxide Poly(methyl methacrylate) Nanocomposite-A New Biomaterial for Denture Bases

(1) Background: The purpose of this in vitro study was to evaluate the color change and stability of a zinc oxide nanoparticle-poly(methyl methacrylate) (ZnO NP-PMMA) nanocomposite for denture base material after immersion in different dietary and cleaning agent solutions. (2) Methods: One hundred samples were prepared and divided into four equinumerous groups depending on the weight content of ZnO NPs. The color coordinates (CIE L*a*b*) were measured using a digital colorimeter, ColorReader (Datacolor AG Europe, Rotkreuz, Switzerland), before and after immersion of the specimens in five different solutions (distilled water, coffee, red wine, black tea, denture cleaning tablet solution) for 6 months. The color changes (ΔE) were calculated using Euclidean distance and analyzed by the Shapiro-Wilk test and the ANOVA/Kruskal-Wallis multiple comparison and adequate post hoc tests. (3) Results: All tested materials showed significant color changes after their exposure to all solutions. Color changes were greatest in the case of red wine and progressed with the duration of the study. (4) Conclusions: The modification of PMMA with ZnO nanoparticles is acceptable in aesthetic terms in 2.5% and 5% weight content; however, color changes are more noticeable with higher nanoparticle content and must be discussed with the patient prior to possible use.

Mg-Doped ZnO Nanoparticles with Tunable Band Gaps for Surface-Enhanced Raman Scattering (SERS)-Based Sensing

Semiconductors have great potential as surface-enhanced Raman scattering (SERS) substrates due to their excellent physiochemical properties. However, they provide low signal enhancements relative to their plasmonic counterparts, which necessitates innovation in their synthesis and application. Substitutional atomic doping is proposed to improve SERS enhancement by controlling electronic properties, such as the band gap. In this work, zinc oxide (ZnO) nanoparticles were synthesized by co-precipitation and doped with magnesium (Mg) at concentrations ranging from 2-10%. Nanoparticle morphology and size were obtained by scanning electron microscopy (SEM). Elemental composition and chemical states were determined using X-ray photoelectron spectroscopy (XPS). Optical properties were obtained with a UV-vis spectrophotometer, while a Raman spectrometer was used to acquire Raman signal enhancements. Stability was assessed by UV-vis spectroscopy, while cytotoxicity was evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results showed that the absorption edge of Mg-doped ZnO nanoparticles was red-shifted compared to pure ZnO nanoparticles. The band gap decreased (3.3-3.01 eV) with increasing Mg doping, while the highest Raman enhancement was observed at 2% doping. No significant cytotoxic effects were observed at low concentrations (3-12 μg/mL). Overall, this study provides evidence for the tunability of ZnO substrates and may serve as a platform for applications in molecular biosensing.

The denture microbiome in health and disease: an exploration of a unique community

The United Nations suggests the global population of denture wearers (an artificial device that acts as a replacement for teeth) is likely to rise significantly by the year 2050. Dentures become colonized by microbial biofilms, the composition of which is influenced by complex factors such as patient’s age and health, and the nature of the denture material. Since colonization (and subsequent biofilm formation) by some micro‐organisms can significantly impact the health of the denture wearer, the study of denture microbiology has long been of interest to researchers. The specific local and systemic health risks of denture plaque are different from those of dental plaque, particularly with respect to the presence of the opportunist pathogen Candida albicans and various other nonoral opportunists. Here, we reflect on advancements in our understanding of the relationship between micro‐organisms, dentures, and the host, and highlight how our growing knowledge of the microbiome, biofilms, and novel antimicrobial technologies may better inform diagnosis, treatment, and prevention of denture‐associated infections, thereby enhancing the quality and longevity of denture wearers.

Assessment of antimicrobial, cytotoxicity, and antiviral impact of a green zinc oxide/activated carbon nanocomposite

This work deals with the synthesis of zinc oxide nanoparticles/activated carbon (ZnO NPs/AC) nanocomposites with different weight ratios (3:1, 1:1, and 1:3), where the antimicrobial, antiviral, and cytotoxicity impact of the formulated nanocomposites were evaluated versus the crude ZnO and AC samples. The formula (3:1; designated Z3C1) exhibited the utmost bactericidal effect against Gram positive group, unicellular and filamentous fungi. Regarding Gram negative group, the sample (Z3C1) was remarkably effective against Klebsiella pneumonia, unlike the case of Escherichia coli. Moreover, the whole samples showed negligible cytotoxicity against the human WI38 cell line, where the most brutality (4%) was exerted by 1000 µg/mL of the formula (Z1C3). Whilst, the formula (Z3C1) exerted the apical inhibition impact against Herpes simplex (HSV1) virus. Consequently, the synthesized (Z3C1) nanocomposite was sorted out to be fully characterized via different physicochemical techniques including FTIR, XRD, SEM, TEM, Zeta potential, TGA, and BET. XRD indicated a predominance of the crystalline pattern of ZnO NPs over the amorphous AC, while the FTIR chart confirmed an immense combination between the ZnO NPs and AC. SEM, TEM, and size distribution images illustrated that the fabricated ZnO NPs/AC was in the nanoscale size swung from 30 to 70 nm. The distinctive surface area of composite material, recording 66.27 m²/g, clearly disclosed its bioactivity toward different bacterial, fungal, and virus species.

Zinc Oxide Nanoparticles: A Review on Its Applications in Dentistry

Nanotechnology in modern material science is a research hot spot due to its ability to provide novel applications in the field of dentistry. Zinc Oxide Nanoparticles (ZnO NPs) are metal oxide nanoparticles that open new opportunities for biomedical applications that range from diagnosis to treatment. The domains of these nanoparticles are wide and diverse and include the effects brought about due to the anti-microbial, regenerative, and mechanical properties. The applications include enhancing the anti-bacterial properties of existing restorative materials, as an anti-sensitivity agent in toothpastes, as an anti-microbial and anti-fungal agent against pathogenic oral microflora, as a dental implant coating, to improve the anti-fungal effect of denture bases in rehabilitative dentistry, remineralizing cervical dentinal lesions, increasing the stability of local drug delivery agents and other applications.

ZnO nanoparticles embedded silk fibroin-a piezoelectric composite for nanogenerator applications

This paper demonstrates a flexible nanogenerator (NG) using Silk-Zinc Oxide (ZnO) composite by exploiting the inherent piezoelectric properties of silk and ZnO. A direct precipitation method was employed to synthesize Zinc Oxide nanoparticles (NPs). Silk-ZnO composite film was then prepared by spin-coating the homogenous silk-ZnO solution. The composition and morphology of silk-ZnO composite were analyzed using various standard characterization procedures. The biocompatibility study of the composite film was also performed through cell viability testing. The utility of as prepared composites was demonstrated through the fabrication of piezoelectric nanogenerator. This hybrid nanogenerator was capable to generate a maximum open circuit voltage of 25 V (peak to peak value) in the bending state for a specific ZnO concentration. The output response of the nanogenerator exhibited a good correlation with the bending angle of the device. A peak outputpower density of 6.67 mW cm^-3was achieved from the nanogenerator. The fabricated prototype is efficient to light-up commercial red LEDs and to harvest energy from human body movement. The piezoelectric coefficient (d₃₃) of silk-ZnO composite film was also experimentally figured out.

Adhesive Bond Integrity of Experimental Zinc Oxide Nanoparticles Incorporated Dentin Adhesive: An SEM, EDX, μTBS, and Rheometric Analysis

OBJECTIVE

Our study is aimed at preparing an experimental adhesive (EA) and assessing the influence of adding 5-10 wt.% concentrations of zinc oxide (ZnO) nanoparticles on the adhesive's mechanical properties.

METHODS

Field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopy were employed to investigate the morphology and elemental distribution of the filler nanoparticles. To examine the adhesive properties, microtensile bond strength (μTBS) testing, an investigation of the rheological properties, degree of conversion (DC), and analysis of the interface between the adhesive and dentin were carried out.

RESULTS

The SEM micrographs of ZnO nanoparticles demonstrated spherical agglomerates. The EDX plotting confirmed the incidence of Zn and oxygen (O) in the ZnO nanoparticles. The highest μTBS was observed for nonthermocycled (NTC) 5 wt.% ZnO group (32.11 ± 3.60 MPa), followed by the NTC-10 wt.% ZnO group (30.04 ± 3.24 MPa). Most of the failures observed were adhesive in nature. A gradual reduction in the viscosity was observed at higher angular frequencies, and the addition of 5 and 10 wt.% ZnO to the composition of the EA lowered its viscosity. The 5 wt.% ZnO group demonstrated suitable dentin interaction by showing the formation of resin tags, while for the 10 wt.% ZnO group, compromised resin tag formation was detected. DC was significantly higher in the 0% ZnO (EA) group.

CONCLUSION

The reinforcement of the EA with 5 and 10 wt.% concentrations of ZnO nanoparticles produced an improvement in the adhesive's μTBS. However, a reduced viscosity was observed for both nanoparticle-reinforced adhesives, and a negotiated dentin interaction was seen for 10 wt.% ZnO adhesive group. Further research exploring the influence of more filler concentrations on diverse adhesive properties is recommended.

Zinc Oxide Nanoparticles Exhibit Favorable Properties to Promote Tissue Integration of Biomaterials

Due to the demographic change, medicine faces a growing demand for tissue engineering solutions and implants. Often, satisfying tissue regeneration is difficult to achieve especially when co-morbidities hamper the healing process. As a novel strategy, we propose the incorporation of zinc oxide nanoparticles (ZnO NPs) into biomaterials to improve tissue regeneration. Due to their wide range of biocompatibility and their antibacterial properties, ZnO NPs are already discussed for different medical applications. As there are versatile possibilities of modifying their form, size, and function, they are becoming increasingly attractive for tissue engineering. In our study, in addition to antibacterial effects of ZnO NPs, we show for the first time that ZnO NPs can foster the metabolic activity of fibroblasts as well as endothelial cells, both cell types being crucial for successful implant integration. With the gelatin sponge method performed on the chicken embryo’s chorioallantoic membrane (CAM), we furthermore confirmed the high biocompatibility of ZnO NPs. In summary, we found ZnO NPs to have very favorable properties for the modification of biomaterials. Here, incorporation of ZnO NPs could help to guide the tissue reaction and promote complication-free healing.

Comparison Study of Cytotoxicity of Bare and Functionalized Zinc Oxide Nanoparticles

In this paper, a study of the cytotoxicity of bare and functionalized zinc oxide nanoparticles (ZnO NPs) is presented. The functionalized ZnO NPs were obtained by various types of biological methods including microbiological (intra- and extracellular with Lactobacillus paracasei strain), phytochemical (Medicago sativa plant extract) and biochemical (ovalbumin from egg white protein) synthesis. As a control, the bare ZnO NPs gained by chemical synthesis (commercially available) were tested. The cytotoxicity was measured through the use of (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) dye as well as lactate dehydrogenase (LDH) assays against murine fibroblast L929 and Caco-2 cell lines. As a complementary method, scanning electron microscopy (SEM) was performed to assess the morphology of the tested cells after treatment with ZnO NPs. The microscopic data confirmed the occurrence of apoptotic blebbing and loss of membrane permeability after the administration of all ZnO NPs. The reactive oxygen species (ROS) concentration during the cell lines’ exposure to ZnO NPs was measured fluorometrically. Additionally, the photocatalytic degradation of methylene blue (MB) dye in the different light conditions, as well as the antioxidant activity of bare and functionalized ZnO NPs, is also reported. The addition of all types of tested ZnO NPs to methylene blue resulted in enhanced rates of photo-degradation in the presence of both types of irradiation, but the application of UV light resulted in higher photocatalytic activity of ZnO NPs. Furthermore, bare (chemically synthetized) NPs have been recognized as the strongest photocatalysts. In the context of the obtained results, a mechanism underlying the toxicity of bio-ZnO NPs, including (a) the generation of reactive oxygen species and (b) the induction of apoptosis, is proposed.

An overview of recent progress in dental applications of zinc oxide nanoparticles

Nanotechnology is an emerging field of science, engineering, and technology concerning the materials in nanoscale dimensions. Several materials are used in dentistry, which can be modified by applying nanotechnology. Nanotechnology has various applications in dentistry to achieve reliable treatment outcomes. The most common nanometals used in dental materials are gold, silver, copper oxide, magnesium oxide, iron oxide, cerium oxide, aluminum oxide, titanium dioxide, and zinc oxide (ZnO). ZnO nanoparticles (NPs), with their unparalleled properties such as high selectivity, enhanced cytotoxicity, biocompatibility, and easy synthesis as important materials were utilized in the field of dentistry. With this background, the present review aimed to discuss the current progress and gain an insight into applications of ZnO NPs in nanodentistry, including restorative, endodontic, implantology, periodontal, prosthodontics, and orthodontics fields.

In-vitro Cytotoxicity Evaluation of Green Synthesized Gold Nanoparticles and Its Indigenous Mouthwash

The aim of this study was to evaluate the cytotoxicity of the prepared Gold Nanoparticles from Triphala Plant extract and of the indigenous mouthwash prepared from these Triphala based gold nanoparticles (AuNP’s) using Artemia salina test. Its objective was to assess whether the prepared mouthwash was safe and biocompatible to use as an alternative to commercial mouthwashes in orthodontic patients to reduce the plaque load around brackets and bands as an adjuvant to tooth brushing. 15 g of brine shrimps was hatched in salt solution after incubating them for 24 – h. Prepared AuNP’s at concentrations 0µL (microliter), 5µL, 10µL, 20µL, 30µL, 50µL were added using a micropipette in one of the microtiter plates and mouthwash prepared from these AuNP’s were added at concentrations 0µL, 10µL, 20µL, 30µL, 40µL, 50µL in another microtiter plate. 10 Hatched nauplii (brine shrimps) were added in each of these microtiter plates and incubated for 24 – h. All nauplii were alive at the end of 24 – h in the microtiter plate containing AuNP’s. At concentrations 0µL, 10µL, 20µL, 30µL nauplii were alive and at 40µL, 50µL concentrations no nauplii were alive at the end of 24 – h in the microtiter plate containing mouthwash. Triphala mediated AuNP’s showed no toxic effect on the brine shrimps. AuNP’s based mouthwash showed excellent compatibility at lower concentrations. Mild toxic effects were elicited at higher concentrations. Hence, AuNP’s could be used to prepare mouthwashes at 20- 30 µL concentrations.

Enhanced Activity and Sustained Release of Protocatechuic Acid, a Natural Antibacterial Agent, from Hybrid Nanoformulations with Zinc Oxide Nanoparticles

Hybrid nanostructures can be developed with inorganic nanoparticles (NPs) such as zinc oxide (ZnO) and natural antibacterials. ZnO NPs can also exert antibacterial effects, and we used them here to examine their dual action in combination with a natural antibacterial agent, protocatechuic acid (PCA). To produce hybrid nanoformulations, we functionalized ZnO NPs with four types of silane organic molecules and successfully linked them to PCA. Physicochemical assessment confirmed PCA content up to ~18% in hybrid nanoformulations, with a PCA entrapment efficiency of ~72%, indicating successful connection. We then investigated the in vitro release kinetics and antibacterial effects of the hybrid against Staphylococcus aureus. PCA release from hybrid nanoformulations varied with silane surface modification. Within 98 h, only 8% of the total encapsulated PCA was released, suggesting sustained long-term release. We used nanoformulation solutions collected at days 3, 5, and 7 by disc diffusion or log reduction to evaluate their antibacterial effect against S. aureus. The hybrid nanoformulation showed efficient antibacterial and bactericidal effects that also depended on the surface modification and at a lower minimum inhibition concentration compared with the separate components. A hybrid nanoformulation of the PCA prodrug and ZnO NPs offers effective sustained-release inhibition of S. aureus growth.

Preparation and Characterisation of Poly(methyl metacrylate)-Titanium Dioxide Nanocomposites for Denture Bases

Introduction of titanium dioxide nanoparticles (TiO₂ NPs) to poly(methyl methacrylate) (PMMA) aims to improve the mechanical, microbiological and tribological properties of dental prosthesis bases. The aim of the research was to assess the polymerisation time and the change in the colour of the new biomaterial. Samples with the 1 wt% and 2 wt% content of TiO₂ additionally modified by ultrasounds were created. The effectiveness of ultrasounds was assessed by comparing the average size of conglomerates in a liquid acrylic resin monomer by means of a dynamic light scattering (DLS) analysis. The biomaterial structure was assessed by the energy-dispersive X-ray spectroscopy (EDS) analysis. The colour change was analysed by means of a colorimetric test and provided in the CIE (Commission internationale de l’éclairage) L*a*b* and RGB (Red Green Blue) colour palette. It was observed during the DLS test that the ultrasonic homogenisation process caused an increase in the suspension heterogeneity. The EDS analysis confirmed the presence of nanoparticles sized below 100 nm, which constitutes a ground for calling the new biomaterial a nanocomposite. The addition of TiO₂ NPs as well as the ultrasounds result in the reduction of the average PMMA polymerisation time. The obtained data reveal that the addition of both 1 wt% and 2 wt% causes a considerable change in the PMMA colour: its whitening. To summarise, the reduced polymerisation time of the new biomaterial fully enables performance of standard procedures related to creation of dental prosthesis bases. Due to the considerable change in the colour, the clinical application is limited to performance of repairs or relining of the prosthesis, where the new material is located in an unaesthetic zone.

Sonochemical approach for synthesis of zinc oxide-poly methyl methacrylate hybrid nanoparticles and its application in corrosion inhibition

Hybrid nanoparticles (HNPs) with zinc oxide and polymethyl metha acrylate (inorganic/ polymer) were synthesized through the exploitation of ultrasound approach. The synthesized HNPs were further characterized employing transmission electron microscopy and x-ray diffraction. ZnO-PMMA based HNPs exhibit excellent protection properties to mild steel from corrosion when gets exposed to acidic condition. Electrochemical impendence spectroscopy (EIS) analysis was accomplished to evaluate the corrosion inhibition performance of MS panel coated with 2 wt% or 4 wt% of HNPs and its comparison with bare panel and that of loaded with only standard epoxy coating., Tafel plot and Nyquist plot analysis depicted that the corrosion current density (I_corr) decreases from 16.7 A/m² for bare material to 0.103 A/m² for 4% coating of HNPs. Applied potential (E_corr) values shifted from negative to positive side. These results were further supported by qualitative analysis. The images taken over a period of time indicated the increase in lifetime of MS panel from 2 to 3 days for bare panel to 10 days for HNPs coated panel, showing that ZnO-PMMA HNPs have potential application in metal protection from corrosion by forming a passive layer.

Development and Evaluation of qPCR Detection Method and Zn-MgO/Alginate Active Packaging for Controlling Listeria monocytogenes Contamination in Cold-Smoked Salmon

To answer to food industry requests to monitor the presence of L. monocytogenes in cold-smoked salmon samples and to extend their shelf-life, a qPCR protocol for the detection of L. monocytogenes, and an antibacterial active packaging reinforced with zinc magnesium oxide nanoparticles (Zn-MgO NPs) were developed. The qPCR allowed the sensitive and easy detection of L. monocytogenes in naturally contaminated samples, with specificity in full agreement with the standard methods. The halo diffusion study indicated a high antibacterial efficiency of 1 mg/mL Zn-MgO NPs against L. monocytogenes, while the flow cytometry showed only moderate cytotoxicity of the nanoparticles towards mammalian cells at a concentration above 1 mg/mL. Thus, the novel active packaging was developed by using 1 mg/mL of Zn-MgO NPs to reinforce the alginate film. Cold-smoked salmon samples inoculated with L. monocytogenes and air-packed with the Zn-MgO NPs-alginate nanobiocomposite film showed no bacterial proliferation at 4 °C during 4 days. In the same condition, L. monocytogenes growth in control contaminated samples packed with alginate film alone. Our results suggest that Zn-MgO nanoparticles can extend the shelf-life of cold-smoked salmon samples.

Microstructure Characterisation and Identification of the Mechanical and Functional Properties of a New PMMA-ZnO Composite

In this research work, we synthesised poly(methyl methacrylate) (PMMA) enriched with 2 wt.% zinc oxide nanoparticles (ZnO) through conventional heat polymerisation and characterised its microstructure. It was found that the distribution of ZnO nanoparticles was homogeneous through the volume of the PMMA. The mechanical testing of the PMMA-ZnO composite primarily included the determination of the compressive properties on real dentures, while density measurements were performed using a pycnometer. The testing of functional properties involved the identification of the colour of the new PMMA-ZnO composite, where pure PMMA acted as a control. In the second step, the PMMA-ZnO cytotoxicity assays were measured in vitro, which were shown to be similar to the control PMMA. Based on this, it could be concluded that the newly formed PMMA-ZnO composite did not induce direct or indirect cytotoxic effects in L929 cell cultures; therefore, according to ISO/DIN 10993-5:2009, this composite was categorised as non-cytotoxic.

A Review of Microwave Synthesis of Zinc Oxide Nanomaterials: Reactants, Process Parameters and Morphoslogies

Zinc oxide (ZnO) is a multifunctional material due to its exceptional physicochemical properties and broad usefulness. The special properties resulting from the reduction of the material size from the macro scale to the nano scale has made the application of ZnO nanomaterials (ZnO NMs) more popular in numerous consumer products. In recent years, particular attention has been drawn to the development of various methods of ZnO NMs synthesis, which above all meet the requirements of the green chemistry approach. The application of the microwave heating technology when obtaining ZnO NMs enables the development of new methods of syntheses, which are characterised by, among others, the possibility to control the properties, repeatability, reproducibility, short synthesis duration, low price, purity, and fulfilment of the eco-friendly approach criterion. The dynamic development of materials engineering is the reason why it is necessary to obtain ZnO NMs with strictly defined properties. The present review aims to discuss the state of the art regarding the microwave synthesis of undoped and doped ZnO NMs. The first part of the review presents the properties of ZnO and new applications of ZnO NMs. Subsequently, the properties of microwave heating are discussed and compared with conventional heating and areas of application are presented. The final part of the paper presents reactants, parameters of processes, and the morphology of products, with a division of the microwave synthesis of ZnO NMs into three primary groups, namely hydrothermal, solvothermal, and hybrid methods.

Eighteen Months Follow-Up with Patient-Centered Outcomes Assessment of Complete Dentures Manufactured Using a Hybrid Nanocomposite and Additive CAD/CAM Protocol

Abstract: The present study aimed to assess the eighteen month follow-up patient-centered outcomes of a simple and predictable protocol for 3D-printed functional complete dentures manufactured using an improved poly(methyl methacrylate) (PMMA)-nanoTiO2. A detailed morphological and structural characterization of the PMMA-TiO2 nanocomposite, using SEM, EDX, XRD, and AFM, after 3D-printing procedure and post-wearing micro-CT, was also performed.

METHODS

A total of 35 fully edentulous patients were enrolled in this prospective study. A 0.4% TiO2-nanoparticle-reinforced PMMA composite with improved mechanical strength, morphologically and structurally characterized, was used according to an additive computer-aided design and computer-aided manufacturing (CAD/CAM) protocol for complete denture fabrication. The protocol proposed involved a three-step appointment process. Before denture insertion, 1 week, 12 month, and 18-month follow up patients were evaluated via the Visual Analogue Scale (VAS, 0-10) and Oral Health Impact Profile for Edentulous Patients (OHIP-EDENT), with a higher score meaning poor quality of life.

RESULTS

A total of 45 complete denture sets were inserted. OHIP-EDENT scored significantly better after 18 months of denture wearing, 20.43 (±4.42) compared to 52.57 (±8.16) before treatment; mean VAS was improved for all parameters assessed.

CONCLUSIONS

Within the limitations of this study, we can state that the proposed workflow with the improved material used is a viable treatment option for patients diagnosed with complete edentulism.

Double-edged effects and mechanisms of Zn2+ microenvironments on osteogenic activity of BMSCs: osteogenic differentiation or apoptosis

Zinc-incorporated biomaterials show promoting effects on osteogenesis; however, excessive zinc ions lead to cytotoxic reactions and also have other adverse effects. Therefore, the double-edged effects of Zn²⁺ microenvironments on osteogenesis may become critical issues for new material development. This study systematically investigated the bidirectional influences of diverse Zn²⁺ microenvironments on the cell adhesion, proliferation, osteogenic differentiation and apoptosis of rBMSCs. Furthermore, the mechanisms of zinc-induced osteogenic differentiation of rBMSCs and of cell apoptosis induced by high concentration of Zn²⁺ were both discussed in detail. The results indicated that the Zn²⁺ microenvironments of 2 μg mL⁻¹ and 5 μg mL⁻¹ effectively improved the initial adhesion and proliferation of rBMSCs, while that of 15 μg mL⁻¹ had exactly the opposite effect. More importantly, the suitable Zn²⁺ microenvironments (2 μg mL⁻¹ and 5 μg mL⁻¹) moderately increased the intracellular Zn²⁺ concentration by regulating zinc transportation, and then activated the MAPK/ERK signaling pathway to induce the osteogenic differentiation of rBMSCs. In contrast, the high Zn²⁺ concentration (15 μg mL⁻¹) not only inhibited the osteogenic differentiation of rBMSCs by damaging intracellular zinc homeostasis, but also induced rBMSC apoptosis by enhancing intracellular ROS generation. The current study clarified the double-edged effects of Zn²⁺ microenvironments on the osteogenic properties of rBMSCs and the related mechanisms, and may provide valuable guidance for optimizing the design of zinc-doped biomaterials and zinc-based alloys.

Dual-directional regulation of diverse Zn²⁺ microenvironments on osteogenic activity of BMSCs plays important roles in the design of zinc-containing biomaterials.

Anticancer and genotoxicity effect of (Clausena lansium (Lour.) Skeels) Peel ZnONPs on neuroblastoma (SH-SY5Y) cells through the modulation of autophagy mechanism

Nanotechnology is an emerged field to develop the plant mediated metal based nanodrugs by green method. In this current study, the zinc oxide metal based nanoparticles were developed using (Clausena lansium (Lour.) Skeels) Peel aqueous extracts and zinc nitrate. The C.L extract zinc nanoparticleswere indicated by the sharp peak seen at 350 nm utilizing the Ultraviolet-Visible spectroscopy (UV-Vis). The high peaks indicate the presence of phytochemicals and its functional groups in ZnONPs were studied by the Fourier Transform Infrared Spectroscopy (FT-IR). The X-Ray Diffraction analysis (XRD) explores the pattern and structure of ZnONPs as spherical and base-centered monoclinic crystalline shapes. The C.L extract with Zn nanoparticles were spherical in nature and the size of the synthesized particles were about 28.42 nm respectively. The autophagy (Beclin-1, LC3-I, LC3-II and ATG4B) and apoptotic (Bax, Bcl-2 and Caspase-3) proteins were regulated by the treatment with ZnONPs in SH-SY5Y neuroblastoma cells. The DNA loss or damage was occurred in the ZnONPs treatment and it was performed using Comet assay. The ZnONPs treatment generates the ROS in the cells and decreased its stability and viability. Addition of NAC prevents ROS in the cultured SH-SY5Y cells and prevents the cells from the apoptosis. We concluded that the ZnONPs potentially kills the neuroblastoma cells by producing the intracellular ROS.

Effect of Antibacterial Silver-Releasing Filler on the Physicochemical Properties of Poly(Methyl Methacrylate) Denture Base Material

Colonization of polymeric dental prosthetic materials by yeast-like fungi and the association of these microorganisms with complications occurring during prosthetic treatment are important clinical problems. In previously presented research, submicron inorganic particles of silver sodium hydrogen zirconium phosphate (S-P) were introduced into poly(methyl methacrylate) (PMMA) denture base material which allowed for obtaining the antimicrobial effect during a 90 day experiment. The aim of the present study was to investigate the flexural strength, impact strength, hardness, wear resistance, sorption, and solubility during three months of storage in distilled water. With increasing S-P concentration after 2 days of conditioning in distilled water, reduced values of flexural strength (107-72 MPa), impact strength (18.4-5.5 MPa) as well as enhanced solubility (0.95-1.49 µg/mm3) were registered, but they were at acceptable levels, and the sorption was stable. Favorable changes included increased hardness (198-238 MPa), flexural modulus (2.9-3.3 GPa), and decreased volume loss during wear test (2.9-0.2 mm3). The percentage changes of the analyzed properties during the 90 days of storage in distilled water were similar for all materials.

Nanoparticles And Human Saliva: A Step Towards Drug Delivery Systems For Dental And Craniofacial Biomaterials

Aim

The aims of this study were to investigate new nano-formulations based on ZnO and Ag nanoparticle (NP) compounds when used against clinical strains of oral gram-positive and gram-negative bacteria, and to examine the stability and behaviour of nano-formulation mixtures in saliva based on different compositions of Ag NPs, ZnO NPs and ZnO+x·Ag NPs. Methods: ZnO NPs with and without nanosilver were obtained by microwave solvothermal synthesis. Then, antibacterial activity was evaluated against bacteria isolated from human saliva. Behavior and nanoparticle solutions were evaluated in human saliva and control (artificial saliva and deionized water). Results were statistically compared.

Results

The NP mixtures had an average size of 30±3 nm, while the commercial Ag NPs had an average size of 55±5 nm. The suspensions displayed differing antibacterial activities and kinetics of destabilisation processes, depending on NPs composition and fluid types.

Conclusion

The present study showed that all NPs suspensions displayed significant destabilisation and high destabilisation over the 24 h of the analyses. The agglomeration processes of NPs in human saliva can be reversible.