Enhanced Antimicrobial Activity of Biofunctionalized Zirconia Nanoparticles

Antimicrobial activity of silver-copper coating against aerosols containing surrogate respiratory viruses and bacteria

The transmission of bacteria and respiratory viruses through expelled saliva microdroplets and aerosols is a significant concern for healthcare workers, further highlighted during the SARS-CoV-2 pandemic. To address this issue, the development of nanomaterials with antimicrobial properties for use as nanolayers in respiratory protection equipment, such as facemasks or respirators, has emerged as a potential solution. In this study, a silver and copper nanolayer called SakCu® was deposited on one side of a spun-bond polypropylene fabric using the magnetron sputtering technique. The antibacterial and antiviral activity of the AgCu nanolayer was evaluated against droplets falling on the material and aerosols passing through it. The effectiveness of the nanolayer was assessed by measuring viral loads of the enveloped virus SARS-CoV-2 and viability assays using respiratory surrogate viruses, including PaMx54, PaMx60, PaMx61 (ssRNA, Leviviridae), and PhiX174 (ssDNA, Microviridae) as representatives of non-enveloped viruses. Colony forming unit (CFU) determination was employed to evaluate the survival of aerobic and anaerobic bacteria. The results demonstrated a nearly exponential reduction in SARS-CoV-2 viral load, achieving complete viral load reduction after 24 hours of contact incubation with the AgCu nanolayer. Viability assays with the surrogate viruses showed a significant reduction in viral replication between 2-4 hours after contact. The simulated viral filtration system demonstrated inhibition of viral replication ranging from 39% to 64%. The viability assays with PhiX174 exhibited a 2-log reduction in viral replication after 24 hours of contact and a 16.31% inhibition in viral filtration assays. Bacterial growth inhibition varied depending on the species, with reductions ranging from 70% to 92% for aerobic bacteria and over 90% for anaerobic strains. In conclusion, the AgCu nanolayer displayed high bactericidal and antiviral activity in contact and aerosol conditions. Therefore, it holds the potential for incorporation into personal protective equipment to effectively reduce and prevent the transmission of aerosol-borne pathogenic bacteria and respiratory viruses.

Nanoparticles and Their Antibacterial Application in Endodontics

Root canal treatment represents a significant challenge as current cleaning and disinfection methodologies fail to remove persistent bacterial biofilms within the intricate anatomical structures. Recently, the field of nanotechnology has emerged as a promising frontier with numerous biomedical applications. Among the most notable contributions of nanotechnology are nanoparticles, which possess antimicrobial, antifungal, and antiviral properties. Nanoparticles cause the destructuring of bacterial walls, increasing the permeability of the cell membrane, stimulating the generation of reactive oxygen species, and interrupting the replication of deoxyribonucleic acid through the controlled release of ions. Thus, they could revolutionize endodontics, obtaining superior results and guaranteeing a promising short- and long-term prognosis. Therefore, chitosan, silver, graphene, poly(lactic) co-glycolic acid, bioactive glass, mesoporous calcium silicate, hydroxyapatite, zirconia, glucose oxidase magnetic, copper, and zinc oxide nanoparticles in endodontic therapy have been investigated in the present review. The diversified antimicrobial mechanisms of action, the numerous applications, and the high degree of clinical safety could encourage the scientific community to adopt nanoparticles as potential drugs for the treatment of endodontic diseases, overcoming the limitations related to antibiotic resistance and eradication of the biofilm.

Synthesis and Structural Characterization of Selenium Nanoparticles-Bacillus sp. MKUST-01 Exopolysaccharide (SeNPs-EPS) Conjugate for Biomedical Applications

Exopolysaccharides (EPS) are exogenous microbial metabolites generated predominantly during the development of bacteria. They have several biological potentials, including antibacterial, antioxidant, and anticancer actions. Polysaccharide-coated nanoparticles have high biological activity and are used in treatments and diagnostics. In this research, selenium nanoparticles (SeNPs) are synthesized and conjugated with bacterial (Bacillus sp. MKUST-01) exopolysaccharide (EPS). Initially, the creation of SeNPs conjugates was verified through UV-Vis spectral examination, which exhibited a prominent peak at 264 nm. Additionally, X-ray diffraction (XRD) analysis further substantiated the existence of crystalline Se, as evidenced by a robust reflection at 29.78°. Another reflection observed at 23.76° indicated the presence of carbon originating from the EPS. Fourier transform infrared spectroscopy (FT-IR) analysis of the EPS capped with SeNPs displayed characteristic peaks at 3425 cm-1, 2926 cm-1, 1639 cm-1, and 1411 cm-1, corresponding to the presence of O-H, C-H, C=O, and COO-groups. The SeNPs themselves were found to possess elongated rod-shaped structures with lengths ranging from 250 to 550 nm and a diameter of less than 70 nm, as confirmed using scanning electron microscopy and particle size analysis. In contrast to the SeNPs, the SeNPs-EPS conjugates showed no hemolytic activity. The overall antioxidant activity of SeNPs-EPS conjugates outperformed 20% higher than SeNPs and EPS. Additionally, experimental observations involving gnotobiotic Artemia nauplii experiments were also recorded, such as the supplementation of EPS and SeNPs-EPS conjugates corresponding to enhanced growth and increased survival rates compared to Artemia nauplii fed with SeNPs and a microalgal diet.

Instantaneous Inactivation of Herpes Simplex Virus by Silicon Nitride Bioceramics

Hydrolytic reactions taking place at the surface of a silicon nitride (Si3N4) bioceramic were found to induce instantaneous inactivation of Human herpesvirus 1 (HHV-1, also known as Herpes simplex virus 1 or HSV-1). Si3N4 is a non-oxide ceramic compound with strong antibacterial and antiviral properties that has been proven safe for human cells. HSV-1 is a double-stranded DNA virus that infects a variety of host tissues through a lytic and latent cycle. Real-time reverse transcription (RT)-polymerase chain reaction (PCR) tests of HSV-1 DNA after instantaneous contact with Si3N4 showed that ammonia and its nitrogen radical byproducts, produced upon Si3N4 hydrolysis, directly reacted with viral proteins and fragmented the virus DNA, irreversibly damaging its structure. A comparison carried out upon testing HSV-1 against ZrO2 particles under identical experimental conditions showed a significantly weaker (but not null) antiviral effect, which was attributed to oxygen radical influence. The results of this study extend the effectiveness of Si3N4's antiviral properties beyond their previously proven efficacy against a large variety of single-stranded enveloped and non-enveloped RNA viruses. Possible applications include the development of antiviral creams or gels and oral rinses to exploit an extremely efficient, localized, and instantaneous viral reduction by means of a safe and more effective alternative to conventional antiviral creams. Upon incorporating a minor fraction of micrometric Si3N4 particles into polymeric matrices, antiherpetic devices could be fabricated, which would effectively impede viral reactivation and enable high local effectiveness for extended periods of time.

Prospective in vitro A431 cell line anticancer efficacy of zirconia nanoflakes derived from Enicostemma littorale aqueous extract

Biomedical applications of zirconia nanomaterials were limited in biological systems. In this research, 8-15 nm size zirconia nanoflakes (ZrNFs) were fabricated and their nature, morphology, and biocompatibility were evaluated. The synthesis was carried out using Enicostemma littorale plant extract as an effective reducing and capping agent. Physiochemical properties of prepared ZrNFs were characterized using diverse instrumental studies such as UV-vis spectrophotometer, Fourier-transform infrared, powder X-ray diffractometer, scanning electron microscope, transmission electron microscope (TEM), energy dispersive X-ray, and cyclic voltammetry (CV). The XRD pattern confirmed the tetragonal phases of ZrNFs and the highest crystallite size of Zr0.02, Zr0.02, and Zr0.06 was 56, 50, and 44 nm, respectively. The morphology of samples was assessed using TEM. Electrophysiological effects of ZrNFs in the cellular interaction process were revealed by the slower rate of electron transfer results in CV demonstration. Biocompatibility of synthesized ZrNFs was studied on A431 human epidermoid carcinoma epithelial cells. The cell viability was increased with an increasing the concentration of nanoflakes up to 6.50-100 μg/mL. The cell viability and observed IC50 values (44.25, 36.49, and 39.62 μg/mL) reveals that the synthesized ZrNFs using E. littorale extract is found to be efficient toxic to A431 cancer cell lines.

New Carbamoyl Surface-Modified ZrO2 Nanohybrids for Selective Au Extraction from E-Waste

Efficient and selective extractions of precious and critical metal ions such as Au(III) and Pd(II) were investigated using zirconia nanoparticles surface modified with different organic mono- and di-carbamoyl phosphonic acid ligands. The modification is made on the surface of commercial ZrO₂ that is dispersed in aqueous suspension and was achieved by optimizing the Bronsted acid-base reaction in ethanol/H₂O solution (1:2), resulting in inorganic-organic systems of ZrO₂-Lⁿ (Lⁿ: organic carbamoyl phosphonic acid ligand). The presence, binding, amount, and stability of the organic ligand on the surface of zirconia nanoparticles were confirmed by different characterizations such as TGA, BET, ATR-FTIR, and ³¹P-NMR. Characterizations showed that all the prepared modified zirconia had a similar specific surface area (50 m².g^-1) and the same amount of ligand on the zirconia surface in a 1:50 molar ratio. ATR-FTIR and ³¹P-NMR data were used to elucidate the most favorable binding mode. Batch adsorption results showed that (i) ZrO₂ surface modified with di-carbamoyl phosphonic acid ligands had the highest adsorption efficiency to extract metals than mono-carbamoyl ligands, and (ii) higher hydrophobicity of the ligand led to better adsorption efficiency. The surface-modified ZrO₂ with di-N,N-butyl carbamoyl pentyl phosphonic acid ligand (ZrO₂-L⁶) showed promising stability, efficiency, and reusability in industrial applications for selective gold recovery. In terms of thermodynamic and kinetic adsorption data, ZrO₂-L⁶ fits the Langmuir adsorption model and pseudo-second-order kinetic model for the adsorption of Au(III) with maximum experimental adsorption capacity q_max = 6.4 mg.g^-1.

Mechanochemical Synthesis of Nanoparticles for Potential Antimicrobial Applications

There is an increased interest in porous materials due to their unique properties such as high surface area, enhanced catalytic properties, and biological applications. Various solvent-based approaches have been already used to synthesize porous materials. However, the use of large volume of solvents, their toxicity, and time-consuming synthesis make this process less effective, at least in terms of principles of green chemistry. Mechanochemical synthesis is one of the effective eco-friendly alternatives to the conventional synthesis. It adopts the efficient mixing of reactants using ball milling without or with a very small volume of solvents, gives smaller size nanoparticles (NPs) and larger surface area, and facilitates their functionalization, which is highly beneficial for antimicrobial applications. A large variety of nanomaterials for different applications have already been synthesized by this method. This review emphasizes the comparison between the solvent-based and mechanochemical methods for the synthesis of mainly inorganic NPs for potential antimicrobial applications, although some metal-organic framework NPs are briefly presented too.

Smart delivery systems for microbial biofilm therapy: Dissecting design, drug release and toxicological features

Bacterial biofilms are highly protected surface attached communities of bacteria that typically cause chronic infections. To address their recalcitrance to antibiotics and minimise side effects of current therapies, smart drug carriers are being explored as promising platforms for antimicrobials. Herein, we briefly summarize recent efforts and considerations that have been applied in the design of these smart carriers. We guide readers on a journey on how they can leverage the inherent biofilm microenvironment, external stimuli, or combine both types of stimuli in a predictable manner. The specific carrier features that are responsible for their 'on-demand' properties are detailed and their impact on antibiofilm property are further discussed. Moreover, an analysis on the impact of such features on drug release profiles is provided. Since nanotechnology represents a significant slice of the drug delivery pie, some insights on the potential toxicity are also depicted. We hope that this review inspires researchers to use their knowledge and creativity to design responsive systems that can eradicate biofilm infections.

Metallic Nanosystems in the Development of Antimicrobial Strategies with High Antimicrobial Activity and High Biocompatibility

Antimicrobial resistance is a major and growing global problem and new approaches to combat infections caused by antibiotic resistant bacterial strains are needed. In recent years, increasing attention has been paid to nanomedicine, which has great potential in the development of controlled systems for delivering drugs to specific sites and targeting specific cells, such as pathogenic microbes. There is continued interest in metallic nanoparticles and nanosystems based on metallic nanoparticles containing antimicrobial agents attached to their surface (core shell nanosystems), which offer unique properties, such as the ability to overcome microbial resistance, enhancing antimicrobial activity against both planktonic and biofilm embedded microorganisms, reducing cell toxicity and the possibility of reducing the dosage of antimicrobials. The current review presents the synergistic interactions within metallic nanoparticles by functionalizing their surface with appropriate agents, defining the core structure of metallic nanoparticles and their use in combination therapy to fight infections. Various approaches to modulate the biocompatibility of metallic nanoparticles to control their toxicity in future medical applications are also discussed, as well as their ability to induce resistance and their effects on the host microbiome.

Electron Beam Irradiation on the Production of a Si- and Zr-Based Hybrid Material: A Study by FTIR and WDXRF

Sol-gel production of hybrid materials has, to some extent, revolutionised materials' engineering and the way science and technology perceive the creation of new materials. Despite that, the method presents some limitations that are circumvented by radiation processing. Electron beam irradiation was used to promote synthesis of hybrid structures while using silanol-terminated PDMS, TEOS and TPOZ as precursors. Evaluation of the method's performance was executed by gel fraction determination, WDXRF and FTIR-ATR. Results showed that, although there is some pre-irradiation reactivity between precursors, radiolysis induces scission on multiple sites of precursor's structures, which induces hybrid network formation to a greater extent. Characterisation allowed determining electron beam irradiation to be effective in the creation of Si-O-Zr bonds, resulting in the production of a Class II hybrid material.

Optimization of Antibacterial, Structures, and Thermal Properties of Alginate-ZrO2 Bionanocomposite by the Taguchi Method

Developing novel antibacterial chemicals is constantly necessary since bacterial resistance to antibiotics is an inevitable occurrence. This research aimed to find the ideal conditions for using antibacterial zirconia (ZrO2) NPs with polymer alginate nanocomposites. Using the Taguchi method, alginate biopolymer, zirconia NPs, and stirring time were utilized to construct nine nanocomposites. Analysis of Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-vis), spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA) indicated the development of nanocomposites with appropriate structural properties. Antibacterial efficacy against Streptococcus mutans (S. mutans) biofilm was the highest when the nanocomposite was formed under the circumstances of experiment 6 (zirconia 8 mg/ml, alginate 70 mg/ml, and 40 min stirring time). Alginate/zirconia bionanocomposites generated using the in situ technique proved efficient against S. mutans. Nanoparticles have a high surface-to-volume ratio and surface energy, which can cause them to agglomerate and make their antimicrobial effectiveness problematic. Using zirconia nanoparticles in an alginate polymer matrix in the form of nanocomposite can increase the stability of nanoparticles. Due to the advantageous antibacterial qualities of this bionanocomposite, it can be utilized in various medical materials and dental appliances.

Nano-antivirals: A comprehensive review

Nanoparticles can be used as inhibitory agents against various microorganisms, including bacteria, algae, archaea, fungi, and a huge class of viruses. The mechanism of action includes inhibiting the function of the cell membrane/stopping the synthesis of the cell membrane, disturbing the transduction of energy, producing toxic reactive oxygen species (ROS), and inhibiting or reducing RNA and DNA production. Various nanomaterials, including different metallic, silicon, and carbon-based nanomaterials and nanoarchitectures, have been successfully used against different viruses. Recent research strongly agrees that these nanoarchitecture-based virucidal materials (nano-antivirals) have shown activity in the solid state. Therefore, they are very useful in the development of several products, such as fabric and high-touch surfaces. This review thoroughly and critically identifies recently developed nano-antivirals and their products, nano-antiviral deposition methods on various substrates, and possible mechanisms of action. By considering the commercial viability of nano-antivirals, recommendations are made to develop scalable and sustainable nano-antiviral products with contact-killing properties.

Peppermint-Mediated Green Synthesis of Nano ZrO2 and Its Adsorptive Removal of Cobalt from Water

Zirconium oxide nanoparticles (ZrO2NPs) were green synthesized for the first time using an aqueous peppermint extract as a precipitating and capping agent. Addition of the extract to Zr4+ solution was followed by calcination of the resulting precipitate at 570 and 700 °C to form ZrO2NPs570 and ZrO2NPs700, respectively. These oxides were characterized using X-ray diffraction, transmission electron microscopy, and BET surface area analysis, and used as adsorbents for cobalt ions (Co2+) in water. The effects of pH, initial Co2+ concentration, ZrO2NPs mass, and contact time on adsorption efficiency were studied. Characterization results showed formation of cubic ZrO2 with average crystallite sizes (XRD data) of 6.27 and 7.26 nm for ZrO2NPs570 and ZrO2NPs700, respectively. TEM images of the two oxides exhibited nearly spherical nanoparticles and BET surface area measurements indicated the formation of mesoporous oxides having surface areas of 94.8 and 62.4 m2/g, respectively. The results of the adsorption study confirmed that the synthesized ZrO2NPs can be efficiently used for the adsorption of Co2+ from water. The uptake of Co2+ from the treated solution is favored at pH values higher than its point of zero charge (6.0). In addition, the adsorption of Co2+ by ZrO2 follows a pseudo-second order kinetics (R2 = 1.0) and can be explained by the Langmuir adsorption isotherm (R2 = 0.973).

Biomolecule conjugated inorganic nanoparticles for biomedical applications: A review

Last decade has witnessed impressive progress in the fields of medicine and bioengineering with the aid of nanomaterials. Nanomaterials are favoured for their improved bio-chemical as well as mechanical properties with tremendous applications in biomedical domains such as disease diagnosis, targeted drug delivery, medical imaging, in vitro diagnostics, designing innovatory cross-functional implants and regenerative tissue engineering. The current situation insists upon crafting nanotools that are capable of catering to biological needs and construct more efficient biomedical strategies. In the recent years, surface functionalization and capping with biomolecules has initiated substantial interest towards research. In this regard, search of suitable biofunctionalized nanoparticles seem to be like finding pearls from ocean. Conjugating biological molecules with inorganic materials has paved the way for unravelling innovative functional materials with dramatically improved properties and a wide range of uses. Inorganic nanoparticles such as metals, metal oxides, as well as quantum dots have been hybridised or conjugated with biomolecules such as proteins, peptides, carbohydrates, and nucleic acids. The present review reports on various biomolecule functionalized inorganic nanomaterials highlighting the biomolecule-inorganic nanoparticle interaction studies, the mechanism of functionalization, antimicrobial efficacy of the functionalised nanoconjugates and its use in various biomedical applications.

Influence of Graphene Sheets on Compaction and Sintering Properties of Nano-Zirconia Ceramics

The use of a nanostructured graphene-zirconia composite will allow the development of new materials with improved performance properties and a high functionality. This work covers a stepwise study related to the creation of a nanostructured composite based on ZrO₂ and graphene. A composite was prepared using two suspensions: nano-zirconia obtained by sol-gel synthesis and oxygen-free graphene obtained sonochemically. The morphology of oxygen-free graphene sheets, phase composition and the morphology of a zirconia powder, and the morphology of the synthesized composite were studied. The effect of the graphene sheets on the rheological and sintering properties of a nanostructured zirconia-based composite powder has been studied. It has been found that graphene sheets in a hybrid nanostructure make it difficult to press at the elastic deformation stage, and the composite passes into the plastic region at a lower pressure than a single nano-zirconia. A sintering mechanism was proposed for a composite with a graphene content of 0.635 wt%, in which graphene is an important factor affecting the process mechanism. It has been determined that the activation energy of the composite sintering is more than two times higher than for a single nano-zirconia. Apparently, due to the van der Waals interaction, the graphene sheets partially stabilize the zirconia and prevent the disordering of the surface monolayers of its nanocrystals and premelting prior to the sintering. This leads to an increase in the activation energy of the composite sintering, and its sintering occurs, according to a mixed mechanism, in which the grain boundary diffusion predominates, in contrast to the single nano-zirconia sintering, which occurs through a viscous flow.

Zirconia-based nanomaterials: recent developments in synthesis and applications

In the last decade, the whole scientific community has witnessed great advances and progress in the various fields of nanoscience. Among the different nanomaterials, zirconia nanomaterials have found numerous applications as nanocatalysts, nanosensors, adsorbents, etc. Additionally, their exceptional biomedical applications in dentistry and drug delivery, and interesting biological properties, viz. anti-microbial, antioxidant, and anti-cancer activity, have further motivated the researchers to explore their physico-chemical properties using different synthetic pathways. With such an interest in zirconia-based nanomaterials, the present review focuses systematically on different synthesis approaches and their impact on the structure, size, shape, and morphology of these nanomaterials. Broadly, there are two approaches, viz., chemical synthesis which includes hydrothermal, solvothermal, sol-gel, microwave, solution combustion, and co-precipitation methods, and a greener approach which employs bacteria, fungus, and plant parts for the preparation of zirconia nanoparticles. In this review article, the aforementioned methods have been critically analyzed for obtaining specific phases and shapes. The review also incorporates a detailed survey of the applications of zirconia-based nanomaterials. Furthermore, the influence of specific phases, morphology, and the comparison with their counterpart composites for different applications have also been included. Finally, the concluding remarks, prospects and possible scope are given in the last section.

Combination Strategies of Different Antimicrobials: An Efficient and Alternative Tool for Pathogen Inactivation

Despite the discovery and development of an array of antimicrobial agents, multidrug resistance poses a major threat to public health and progressively increases mortality. Recently, several studies have focused on developing promising solutions to overcome these problems. This has led to the development of effective alternative methods of controlling antibiotic-resistant pathogens. The use of antimicrobial agents in combination can produce synergistic effects if each drug invades a different target or signaling pathway with a different mechanism of action. Therefore, drug combinations can achieve a higher probability and selectivity of therapeutic responses than single drugs. In this systematic review, we discuss the combined effects of different antimicrobial agents, such as plant extracts, essential oils, and nanomaterials. Furthermore, we review their synergistic interactions and antimicrobial activities with the mechanism of action, toxicity, and future directions of different antimicrobial agents in combination. Upon combination at an optimum synergistic ratio, two or more drugs can have a significantly enhanced therapeutic effect at lower concentrations. Hence, using drug combinations could be a new, simple, and effective alternative to solve the problem of antibiotic resistance and reduce susceptibility.

Antimicrobial, antibiofilm, and anticancer potential of silver nanoparticles synthesized using pigment-producing Micromonospora sp. SH121

Silver nanoparticles (AgNPs) have gained interest as an alternative pharmaceutical agent because of antimicrobial resistance and drug toxicity. Considering the increasing request, eco-friendly, sustainable, and cost-effective synthesis of versatile AgNPs has become necessary. In this study, green-made AgNPs were successfully synthesized using Micromonospora sp. SH121 (Mm-AgNPs). Synthesis was verified by surface plasmon resonance (SPR) peak at 402 nm wavelength in the UV-Visible (UV-Vis) absorption spectrum. Scanning electron microscopy (SEM) analysis depicted that Mm-AgNPs were in the size range of 10-30 nm and spherical. Fourier transform infrared spectroscopy (FTIR) confirmed the existence of bioactive molecules on the surface of nanoparticles. The X-ray diffraction (XRD) analysis revealed the face-centered cubic (fcc) structure of the Mm-AgNPs. Their polydispersity index (PDI) and zeta potential were 0. 284 and -35.3 mV, respectively. Mm-AgNPs (4-32 µg/mL) exhibited strong antimicrobial activity against Bacillus cereus, Enterococcus faecalis, Enterococcus hirae, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Pseudomonas putida, Staphylococcus epidermidis, Streptococcus pneumoniae, and Aspergillus flavus. Mm-AgNPs partially inhibited the biofilm formation in Acinetobacter baumannii, E. coli, K. pneumoniae, and Pseudomonas aeruginosa. Furthermore, results showed that low concentrations of Mm-AgNPs (1 and 10 µg/mL) caused higher cytotoxicity and apoptosis in DU 145 cells than human fibroblast cells. Based on the results, Mm-AgNPs have an excellent potential for treating infectious diseases and prostate cancer.

Potential of metal and metal oxide nanoparticles in plant disease diagnostics and management: Recent advances and challenges

Plant diseases caused by phytopathogens are a severe threat to global food production. Management of plant diseases mostly rely on the application of pesticides which have several adverse effects on the ecosystem. Innovative and high-performance diagnostic tools are useful for the early detection of phytopathogens. Emerging role of metal and metal oxides nanoparticles (NPs) in plant disease diagnostics to combat crop diseases has been described. These NPs constitute new weapons against plant pathogens and facilitate the early diagnosis/management of crop diseases specifically in resource-poor conditions. The interactions between NPs, phytopathogens and plants showed great diversity and multiplicity which reduces chances of the development of resistant pathogen strains. The present article discusses the available literature as well as challenges and research gaps that are essential in the successful utilization of metal and metal oxide NPs for precise and timely detection and management of plant diseases.

Safer plant-based nanoparticles for combating antibiotic resistance in bacteria: A comprehensive review on its potential applications, recent advances, and future perspective

BACKGROUND

Antibiotic resistance is one of the current threats to human health, forcing the use of drugs that are more noxious, costlier, and with low efficiency. There are several causes behind antibiotic resistance, including over-prescription of antibiotics in both humans and livestock. In this scenario, researchers are shifting to new alternatives to fight back this concerning situation.

SCOPE AND APPROACH

Nanoparticles have emerged as new tools that can be used to combat deadly bacterial infections directly or indirectly to overcome antibiotic resistance. Although nanoparticles are being used in the pharmaceutical industry, there is a constant concern about their toxicity toward human health because of the involvement of well-known toxic chemicals (i.e., sodium/potassium borohydride) making their use very risky for eukaryotic cells.

KEY FINDINGS AND CONCLUSIONS

Multiple nanoparticle-based approaches to counter bacterial infections, providing crucial insight into the design of elements that play critical roles in the creation of antimicrobial nanotherapeutic drugs, are currently underway. In this context, plant-based nanoparticles will be less toxic than many other forms, which constitute promising candidates to avoid widespread damage to the microbiome associated with current practices. This article aims to review the actual knowledge on plant-based nanoparticle products for antibiotic resistance and the possible replacement of antibiotics to treat multidrug-resistant bacterial infections.

Review on synthesis, properties and multifarious therapeutic applications of nanostructured zirconia in dentistry

Amongst dental ceramics, nano zirconia (ZrNp) has shown exceptional developments in the field of dentistry in recent years. Zirconia is an oxide that possess superior optical, mechanical, and biological properties. As a novel nanoparticle, it has been widely used in various fields of dentistry due to its improved mechanical properties, biocompatibility, and stable structure. Provision of metal free solutions is one of the prime requirements in dental materials. Many metal alloys used extensively possess unaesthetic colors and display chemical interactions in the oral cavity encouraging use of zirconia for dental use. Use of ZrNp based ceramics has increased due to its resistance to corrosion, superior color matching that enhances esthetics and improved strength compared to conventional biomaterials. This review discusses the recent scientific literature on the synthesis, properties and types, applications, and toxicity of ZrNp in the field of dentistry.

Recent trends and advances in polyindole-based nanocomposites as potential antimicrobial agents: a mini review

Infections caused by multi-drug resistant microbes are a big challenge to the medical field and it necessitates the need for new biomedical agents that can act as potential candidates against these pathogens. Several polyindole based nanocomposites were found to exhibit the ability to release reactive oxygen species (ROS) and hence they show excellent antimicrobial properties. The features of polyindole can be fine-tuned to make them potential alternatives to antibiotics and antifungal medicines. This review clearly portrays the antimicrobial properties of polyindole based nanocomposites, reported so far for biomedical applications. This review will give a clear insight into the scope and possibilities for further research on the biomedical applications of polyindole based nanocomposites.

Engineered Nanomaterials in Soil: Their Impact on Soil Microbiome and Plant Health

A staggering number of nanomaterials-based products are being engineered and produced commercially. Many of these engineered nanomaterials (ENMs) are finally disposed into the soil through various routes in enormous quantities. Nanomaterials are also being specially tailored for their use in agriculture as nano-fertilizers, nano-pesticides, and nano-based biosensors, which is leading to their accumulation in the soil. The presence of ENMs considerably affects the soil microbiome, including the abundance and diversity of microbes. In addition, they also influence crucial microbial processes, such as nitrogen fixation, mineralization, and plant growth promoting activities. ENMs conduct in soil is typically dependent on various properties of ENMs and soil. Among nanoparticles, silver and zinc oxide have been extensively prepared and studied owing to their excellent industrial properties and well-known antimicrobial activities. Therefore, at this stage, it is imperative to understand how these ENMs influence the soil microbiome and related processes. These investigations will provide necessary information to regulate the applications of ENMs for sustainable agriculture and may help in increasing agrarian production. Therefore, this review discusses several such issues.

Design and development of electrospun SPEEK incorporated with aminated zirconia and curcumin nanofibers for periodontal regeneration

Periodontal disease disturbs the supportive tissues around the teeth such as connective tissue, gingival tissue, periodontal ligaments and alveolar bone. Previously, treatment of periodontitis was embattled by repopulating the affected site with cells that has capacity to regenerate damaged tissue by endorsing the perception of guided tissue regeneration but it entails additional surgery owing to non-biodegradability. Biodegradable polymeric nanofibrous scaffold imitating extracellular matrix (ECM) delivering functionalized nanoparticles loaded with therapeutic drug have the ability to support cellular functions thereby enhancing regeneration. Present study explores novel amine functionalized zirconia nanoparticle loaded curcumin incorporated SPEEK nanofibrous scaffolds to address periodontal regeneration. Zirconia - crown of dental therapeutics, its amine functionalization further enhanced the strength and cyto-compatibility. Carbon-Silica NMR (59.9 and 69.8 ppm), FT-IR (3426 cm^-1), EDAX and XRD (28.9°_, 31.6° and 38.2° pertaining to [-1 1 1], [1 1 1] and [1 2 0] planes) analysis confirmed the effective functionalization of the zirconia nanoparticle with the amine group. Electrospinning was carried out at a voltage of 20 kV and flow rate of 0.05 ml/h. Fabricated nanofibers were highly dense, porous with interconnected fibrous structures that bio-mimic ECM. They exhibited an average diameter of 187 ± 2 nm (SPEEK), 192 ± 2 nm (SPEEK + NH₂-ZrO₂), and 256 ± 17 nm (SPEEK + NH₂-ZrO₂+Cur). Extensively discovered anti-bacterial traits of curcumin supplemented the advantage for the treatment of periodontitis. Incorporated materials improve the physico-chemical, mechanical and biological characteristics of nanofibers. FT-IR, EDAX and XRD analysis of the fabricated nanofibrous scaffold demonstrated the effective incorporation of aminated zirconia loaded curcumin. Results of cyto-compatibility analysis of SPEEK + NH₂-ZrO₂+Cur nanofibrous scaffold depicted a cell viability of 100 ± 1.62%. Results of anti-bacterial assay with zone of inhibition was 6.5 ± 0.5 mm (SPEEK), 7.5 ± 1 mm (SPEEK + NH₂-ZrO₂), and 8 ± 1 mm (SPEEK + NH₂-ZrO₂+Cur). Thus, the fabricated bio-material is cyto-compatible, non-toxic and effective against pathogens exploiting higher potential for periodontal regeneration applications.

High adsorption of sodium diclofenac on post-synthetic modified zirconium-based metal-organic frameworks: Experimental and theoretical studies

Water pollution by pharmaceuticals is currently a great concern due to their ecological risks. In this study, zirconium-based metal-organic frameworks (UiO-66-(COOH)₂) were used for removal of the nonsteroidal anti-inflammatory drug (NSAID) diclofenac sodium (DCF). They have been synthesized using a hydrothermal method. Copper and iron metal ions were incorporated in the framework using post-synthetic modification techniques to produce UiO-66-(COOCu)₂ and UiO-66-(COOFe)₂. The resulted MOFs were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning/transmission electron microscopy, and Brunauer-Emmett-Teller. The effects of the pH, initial concentration, and adsorption time on the adsorption process of diclofenac were studied. The maximum adsorption capacities obtained on UiO-66-(COOH)₂, UiO-66-(COOCu)₂, and UiO-66-(COOFe)₂ were 480.5, 624.3, and 769.1 mg/g, respectively. The adsorption of diclofenac was found to be better fitted with Langmuir isotherm and pseudo-second-order kinetic models. The adsorption mechanism was investigated using XRD, FT-IR, density functional theory and Monte Carlo simulation, in which the latter method was used to calculate the adsorption energies and determine the possible interactions between diclofenac and the adsorbents. UiO-66-(COOH)₂, UiO-66-(COOCu)₂, and UiO-66-(COOFe)₂ exhibited good recyclability for diclofenac removal, which confirms the sustainability of these materials.

Multimetallic Nanoparticles as Alternative Antimicrobial Agents: Challenges and Perspectives

Recently, infectious diseases caused by bacterial pathogens have become a major cause of morbidity and mortality globally due to their resistance to multiple antibiotics. This has triggered initiatives to develop novel, alternative antimicrobial materials, which solve the issue of infection with multidrug-resistant bacteria. Nanotechnology using nanoscale materials, especially multimetallic nanoparticles (NPs), has attracted interest because of the favorable physicochemical properties of these materials, including antibacterial properties and excellent biocompatibility. Multimetallic NPs, particularly those formed by more than two metals, exhibit rich electronic, optical, and magnetic properties. Multimetallic NP properties, including size and shape, zeta potential, and large surface area, facilitate their efficient interaction with bacterial cell membranes, thereby inducing disruption, reactive oxygen species production, protein dysfunction, DNA damage, and killing potentiated by the host's immune system. In this review, we summarize research progress on the synergistic effect of multimetallic NPs as alternative antimicrobial agents for treating severe bacterial infections. We highlight recent promising innovations of multimetallic NPs that help overcome antimicrobial resistance. These include insights into their properties, mode of action, the development of synthetic methods, and combinatorial therapies using bi- and trimetallic NPs with other existing antimicrobial agents.

Tangerine mediated synthesis of zirconia as potential protective dental coatings

Demand of bioactive materials that may create a bacteria-free environment while healing and regenerating the defect area is increasing day by day. Zirconia is a very interesting material because of its biocompatibility and high fracture toughness. In this research work, zirconia nanoparticles (NPs) have been synthesized using sol-gel method. Molarity of sols is varied in the range of 25 to 125 mM. The effect of acidic and basic nature of sols is studied by maintaining acidic (2) and basic (9) pH. As-synthesized NPs are made soluble in deionized (DI) water using tangerine drops. Dissolved NPs are spin coated onto glass substrate prior to characterization. Pure tetragonal phase, observed under all conditions using basic medium (pH 9), is accompanied by smaller crystallite size and unit cell volume. Presence of stabilized zirconia phase leads to higher value of density and higher mechanical strength. Nanodendrites with distinct features are observed for the sample prepared with high molarity using basic medium. Whereas, soft agglomerated nanodendrites are observed using acidic medium. Optical properties show transmission of 60-80% in the visible and infrared regions for acidic based samples and ~84% for basic samples. Direct energy band gap is varied from 4.96 eV to 5.1 eV in acidic (pH 2) and 4.91 eV to 4.97 eV in basic (pH 9) media. FTIR spectra show the formation of fundamental tetragonal band at 490 cm^-1 for basic samples. Antibacterial response of zirconia is tested against E. coli, Streptococcus and Bacillus bacteria. Human teeth, bare and zirconia coated, are tested for their possible weight loss after dipping in various beverages. Zirconia coated tooth shows negligible degradation in hardness and weight after 24 hr dipping period. Thus, coatings prepared using water soluble zirconia (WSZ) nanoparticles, without the use of toxic solvents/reagents, are promising material to be used as protective coatings in biomedical applications.

Zinc-Based Nanomaterials for Diagnosis and Management of Plant Diseases: Ecological Safety and Future Prospects

A facet of nanorenaissance in plant pathology hailed the research on the development and application of nanoformulations or nanoproducts for the effective management of phytopathogens deterring the growth and yield of plants and thus the overall crop productivity. Zinc nanomaterials represent a versatile class of nanoproducts and nanoenabled devices as these nanomaterials can be synthesized in quantum amounts through economically affordable processes/approaches. Further, these nanomaterials exhibit potential targeted antimicrobial properties and low to negligible phytotoxicity activities that well-qualify them to be applied directly or in a deviant manner to accomplish significant antibacterial, antimycotic, antiviral, and antitoxigenic activities against diverse phytopathogens causing plant diseases. The photo-catalytic, fluorescent, and electron generating aspects associated with zinc nanomaterials have been utilized for the development of sensor systems (optical and electrochemical biosensors), enabling quick, early, sensitive, and on-field assessment or quantification of the test phytopathogen. However, the proficient use of Zn-derived nanomaterials in the management of plant pathogenic diseases as nanopesticides and on-field sensor system demands that the associated eco- and biosafety concerns should be well discerned and effectively sorted beforehand. Current and possible utilization of zinc-based nanostructures in plant disease diagnosis and management and their safety in the agroecosystem is highlighted.

Long-Term Sorption and Solubility of Zirconia-Impregnated PMMA Nanocomposite in Water and Artificial Saliva

Exposure of denture base acrylic resins to the oral environment and storage media for extended periods of time results in sorption of saliva or water, leading to a reduction in physical properties and thus clinical service life. The purpose of this in vitro study was to assess the sorption and solubility of high-impact heat-polymerised denture base acrylic resin (HI PMMA) impregnated with zirconia nanoparticles after being stored for 180 days in distilled water (DW) and artificial saliva (AS). The specimens were divided into six groups for each storage medium, according to the concentration of zirconia nanoparticles (0, 1.5, 3.0, 5.0, 7.0, and 10.0 wt.%). Data were statistically analysed for sorption and solubility using one-way and two-way ANOVA statistical tests. Sorption in DW and AS for all groups containing zirconia showed sorption values lower than the control group at 90 days, though not significantly different (p > 0.05) compared to the control group. For both the DW and AS groups, the lowest solubility value was measured in the group containing 3 wt.% zirconia, however, there was no significant difference compared to the control group except when observing 10 wt.% zirconia in AS, which showed a significantly higher solubility (p < 0.05). High-impact PMMA, impregnated with low concentrations of ZrO₂, showed the lowest sorption and solubility in both media, but was not significantly different compared to pure HI PMMA.

Photocatalytic and bactericidal properties and molecular docking analysis of TiO2 nanoparticles conjugated with Zr for environmental remediation

Despite implementing several methodologies including a combination of physical, chemical and biological techniques, aquatic and microbial pollution remains a challenge to this day. Recently, nanomaterials have attracted considerable attention due to their extraordinary prospective for utilization toward environmental remediation. Among several probable candidates, TiO₂ stands out due to its potential for use in multifaceted applications. One way to improve the catalytic and antimicrobial potential of TiO₂ is to dope it with certain elements. In this study, Zr-doped TiO₂ was synthesized through a sol–gel chemical method using various dopant concentrations (2, 4, 6, and 8 wt%). Surface morphological, microstructural and elemental analysis was carried out using FESEM and HR-TEM along with EDS to confirm the formation of Zr–TiO₂. XRD spectra showed a linear shift of the (101) anatase peak to lower diffraction angles (from 25.4° to 25.08°) with increasing Zr⁴⁺ concentration. Functional groups were examined via FTIR, an ample absorption band appearing between 400 and 700 cm⁻¹ in the acquired spectrum was attributed to the vibration modes of the Ti–O–Ti linkage present within TiO₂ nanoparticles, which denotes the formation of TiO₂. Experimental results indicated that with increasing dopant concentrations, photocatalytic potential was enhanced significantly. In this respect, TiO₂ doped with 8 wt% Zr (sample 0.08 : 1) exhibited outstanding performance by realizing 98% elimination of synthetic MB in 100 minutes. This is thought to be due to a decreased rate of electron–hole pair recombination that transpires upon doping. Therefore, it is proposed that Zr-doped TiO₂ can be used as an effective photocatalyst material for various environmental and wastewater treatment applications. The good docking scores and binding confirmation of Zr-doped TiO₂ suggested doped nanoparticles as a potential inhibitor against selected targets of both E. coli and S. aureus. Hence, enzyme inhibition studies of Zr-doped TiO₂ NPs are suggested for further confirmation of these in silico predictions.

Despite implementing several methodologies including a combination of physical, chemical and biological techniques, aquatic and microbial pollution remains a challenge to this day.