A Review on Green Synthesis of TiO2 NPs: Synthesis and Applications in Photocatalysis and Antimicrobial

Preparation of titanium dioxide nanoparticles from Solanum Tuberosum peel extract and its applications

The present study describes a method for the preparation of green titanium dioxide (TiO2) nanoparticles from the peel of Solanum tuberosum, commonly known as potato, and the potato peel being a kitchen waste. The green synthesized TiO2 (G- TiO2) nanoparticles were characterized using UV-visible spectroscopy, dynamic light scattering, scanning electron microscopy, TEM, XRD, and FTIR spectroscopy. The photocatalytic activity of the G- TiO2 nanoparticles was also shown using the dye bromophenol blue. To explore the biocompatibility of the G- TiO2, the cell viability in normal as well as cancer cells was assessed. Further, the in vivo toxicity of the G- TiO2 nanoparticles was assessed using zebrafish embryos. The novelty of the present invention is to utilize kitchen waste for a useful purpose for the synthesis of titanium dioxide nanoparticles which is known to have UV light scavenging properties. Moreover, the potato peel is a natural antioxidant and possesses a skin-lightening effect. A combination of the potato peel extract and titanium dioxide prepared using the extract will have a combinatorial effect for protecting UV light exposure to the skin and lightening the skin colour.

Mechanistic Insights into Toxicity of Titanium Dioxide Nanoparticles at the Micro- and Macro-levels

Titanium oxide nanoparticles (TiO2 NPs) have been regarded as a legacy nanomaterial due to their widespread usage across multiple fields. The TiO2 NPs have been and are still extensively used as a food and cosmetic additive and in wastewater and sewage treatment, paints, and industrial catalysis as ultrafine TiO2. Recent developments in nanotechnology have catapulted it into a potent antibacterial and anticancer agent due to its excellent photocatalytic potential that generates substantial amounts of highly reactive oxygen radicals. The method of production, surface modifications, and especially size impact its toxicity in biological systems. The anatase form of TiO2 (<30 nm) has been found to exert better and more potent cytotoxicity in bacteria as well as cancer cells than other forms. However, owing to the very small size, anatase particles are able to penetrate deep tissue easily; hence, they have also been implicated in inflammatory reactions and even as a potent oncogenic substance. Additionally, TiO2 NPs have been investigated to assess their toxicity to large-scale ecosystems owing to their excellent reactive oxygen species (ROS)-generating potential compounded with widespread usage over decades. This review discusses in detail the mechanisms by which TiO2 NPs induce toxic effects on microorganisms, including bacteria and fungi, as well as in cancer cells. It also attempts to shed light on how and why it is so prevalent in our lives and by what mechanisms it could potentially affect the environment on a larger scale.

Biosynthesis of TiO2/CuO and Its Application for the Photocatalytic Removal of the Methylene Blue Dye

In this study, we successfully synthesized a TiO2/CuO nanocomposite using the aqueous extract of Impatiens tinctoria A.rich. leaf extract as a capping, reducing, and stabilizing agent for the first time in an environmentally friendly, low-cost, straightforward, and sustainable technique. Numerous characterization techniques such as ultraviolet-visible diffuse reflectance spectroscopy (UV-vis-DRS), photoluminescence (PL), Raman spectroscopy, Fourier-transform infrared (FTIR), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), and high resolution TEM (HRTEM) were used to characterize the obtained TiO2/CuO nanocomposite. XRD verified that the TiO2/CuO nanocomposite has an average crystallite size of about 21 nm. The TEM result revealed an average particle size of 29 nm for the biosynthesized TiO2/CuO NC. The HRTEM analysis showed the presence of polycrystalline structures with the predominant lattice fringes 0.352 and 0.19 which were attributed to anatase phase TiO2 in the crystal plane of (101) and (200), respectively. The lattice fringes for monoclinic CuO were observed with values of 0.213 and 0.252 for the lattice planes of (111) and (111̅), respectively. The photoluminescence spectroscopic analysis revealed that the TiO2/CuO NC showed the lowest intensity compared to the pristine TiO2 and CuO indicating the reduction of exciton recombination in the case of the TiO2/CuO NC. The BET analysis showcased the formation of mesoporous materials with a surface area of 87.5 m2/g. The photocatalytic degradation performance of the biosynthesized TiO2, CuO, and TiO2/CuO nanomaterials against the potentially harmful MB dye was tested using the light source of a 150 tungsten-halogen lamp with a wavelength range of 360-2800 nm. The factors affecting photodegradation efficiencies like catalyst dose (20 mg), dye concentration(15 ppm), pH (9), and reaction time (90 min) were optimized for the degradation of the MB dye. The TiO2/CuO catalyst showed the highest degradation efficiency of 99% under the optimized conditions. The degradation rate of the MB dye in the presence of the TiO2/CuO NC was evaluated and found to be fitted to the pseudo-first-order kinetics with a rate constant of 0.03 min-1. The reusability test of the TiO2/CuO catalyst showed its good stability.

Optimizing the green synthesis of antibacterial TiO2 - anatase phase nanoparticles derived from spinach leaf extract

Titanium dioxide nanoparticles, renowned for their abundance, non-toxicity, and stability, have emerged as indispensable components in various fields such as air purification, healthcare, and industrial processes. Their applications as photocatalysts and antibacterial agents are particularly prominent. The synthesis methods significantly influence the properties and subsequent applications of these nanoparticles. While several techniques exist, the biological approach using plant extracts offers advantages such as simplicity, biocompatibility, and cost-effectiveness. This study focused on the green synthesis of titanium dioxide nanoparticles utilizing spinach leaf extract. Within the scope of this investigation, the green synthesis of titanium dioxide nanoparticles through spinach leaf extract were synthesized and optimized, followed by a comprehensive examination of their morphological, structural, and chemical attributes with UV-visible spectroscopy, FTIR spectroscopy, XRD, FESEM, and EDX. The minimum inhibitory concentration (MIC) against E. coli and S. aureus was determined to evaluate their antibacterial potential. Optimal synthesis conditions were identified at 50 °C, using a 1/30 concentration and 20 ml of spinach leaf extract. Spherical anatase nanoparticles, ranging from 10 to 40 nm, were produced under these conditions. The change in the color of the extract, absorption at 247 nm, change and increase of the peak at 800 - 400 wavelengths, and the maximum intensity of X-ray diffraction at the angle of 25.367 with the crystal plane 101 were indications of the synthesis of these nanoparticles. Notably, the synthesized nanoparticles exhibited antibacterial activity with MIC values of 0.5 mg/ml against E. coli and 2 mg/ml against S. aureus. This research presents a novel, eco-friendly approach to synthesizing titanium dioxide nanoparticles with promising antibacterial properties.

Titanium Dioxide Nanomaterials: Progress in Synthesis and Application in Drug Delivery

Background: Recent developments in nanotechnology have provided efficient and promising methods for the treatment of diseases to achieve better therapeutic results and lower side effects. Titanium dioxide (TiO2) nanomaterials are emerging inorganic nanomaterials with excellent properties such as low toxicity and easy functionalization. TiO2 with special nanostructures can be used as delivery vehicles for drugs, genes and antigens for various therapeutic options. The exploration of TiO2-based drug delivery systems shows great promise for translating nanotechnology into clinical applications; Methods: Comprehensive data on titanium dioxide were collected from reputable online databases including PubMed, GreenMedical, Web of Science, Google Scholar, China National Knowledge Infrastructure Database, and National Intellectual Property Administration; Results: In this review, we discuss the synthesis pathways and functionalization strategies of TiO2. Recent advances of TiO2 as a drug delivery system, including sustained and controlled drug release delivery systems were introduced. Rigorous long-term systematic toxicity assessment is an extremely critical step in application to the clinic, and toxicity is still a problem that needs to be closely monitored; Conclusions: Despite the great progress made in TiO2-based smart systems, there is still a great potential for development. Future research may focus on developing dual-reaction delivery systems and single-reaction delivery systems like redox and enzyme reactions. Undertaking thorough in vivo investigations is necessary prior to initiating human clinical trials. The high versatility of these smart drug delivery systems will drive the development of novel nanomedicines for personalized treatment and diagnosis of many diseases with poor prognosis.

Inorganic nanoparticles incorporated with transdermal drug delivery systems

INTRODUCTION

Transdermal drug delivery (TDD) is becoming more recognized as a noninvasive method particularly suitable for vulnerable populations. TDD offers an alternative to oral drug delivery, bypassing issues related to poor absorption and metabolism. However, the application of TDD is limited to a few drugs due to the skin's barrier. Various techniques, including passive methods like nanoparticles (NPs), are being explored to enhance drug permeability through the skin.

AREAS COVERED

This review shows the benefit of incorporating inorganic NPs with TDD in improving drug delivery through the skin. Despite the potential of these techniques, there are currently only a few research studies that utilize them. This review addresses the scarcity of research incorporating inorganic NPs with TDD. It also aims to summarize both inorganic NPs and TDD in the pharmaceutical industry, highlighting the advantages of incorporating these novel drug delivery systems with each other.

EXPERT OPINION

Given the potential benefits of incorporating inorganic NPs into TDD systems, there is a need for increased research and attention in this area. The review encourages scientists to address the existing research gap and explore the advantages of combining these innovative drug delivery systems to advance the field.

Applications of nanotechnology in orthodontics: a comprehensive review of tooth movement, antibacterial properties, friction reduction, and corrosion resistance

Nanotechnology has contributed important innovations to medicine and dentistry, and has also offered various applications to the field of orthodontics. Intraoral appliances must function in a complex environment that includes digestive enzymes, a diverse microbiome, mechanical stress, and fluctuations of pH and temperature. Nanotechnology can improve the performance of orthodontic brackets and archwires by reducing friction, inhibiting bacterial growth and biofilm formation, optimizing tooth remineralization, improving corrosion resistance and biocompatibility of metal substrates, and accelerating or decelerating orthodontic tooth movement through the application of novel nanocoatings, nanoelectromechanical systems, and nanorobots. This comprehensive review systematically explores the orthodontic applications of nanotechnology, particularly its impacts on tooth movement, antibacterial activity, friction reduction, and corrosion resistance. A search across PubMed, the Web of Science Core Collection, and Google Scholar yielded 261 papers, of which 28 met our inclusion criteria. These selected studies highlight the significant benefits of nanotechnology in orthodontic devices. Recent clinical trials demonstrate that advancements brought by nanotechnology may facilitate the future delivery of more effective and comfortable orthodontic care.

Progress in the Sustainable Development of Biobased (Nano)materials for Application in Water Treatment Technologies

Water pollution remains a widespread problem, affecting the health and wellbeing of people around the globe. While current advancements in wastewater treatment and desalination show promise, there are still challenges that need to be overcome to make these technologies commercially viable. Nanotechnology plays a pivotal role in water purification and desalination processes today. However, the release of nanoparticles (NPs) into the environment without proper safeguards can lead to both physical and chemical toxicity. Moreover, many methods of NP synthesis are expensive and not environmentally sustainable. The utilization of biomass as a source for the production of NPs has the potential to mitigate issues pertaining to cost, sustainability, and pollution. The utilization of biobased nanomaterials (bio-NMs) sourced from biomass has garnered attention in the field of water purification due to their cost-effectiveness, biocompatibility, and biodegradability. Several research studies have been conducted to efficiently produce NPs (both inorganic and organic) from biomass for applications in wastewater treatment. Biosynthesized materials such as zinc oxide NPs, phytogenic magnetic NPs, biopolymer-coated metal NPs, cellulose nanocrystals, and silver NPs, among others, have demonstrated efficacy in enhancing the process of water purification. The utilization of environmentally friendly NPs presents a viable option for enhancing the efficiency and sustainability of water pollution eradication. The present review delves into the topic of biomass, its origins, and the methods by which it can be transformed into NPs utilizing an environmentally sustainable approach. The present study will examine the utilization of greener NPs in contemporary wastewater and desalination technologies.

Nanomaterial in controlling biofilms and virulence of microbial pathogens

The escalating threat of antimicrobial resistance (AMR) poses a grave concern to global public health, exacerbated by the alarming shortage of effective antibiotics in the pipeline. Biofilms, intricate populations of bacteria encased in self-produced matrices, pose a significant challenge to treatment, as they enhance resistance to antibiotics and contribute to the persistence of organisms. Amid these challenges, nanotechnology emerges as a promising domain in the fight against biofilms. Nanomaterials, with their unique properties at the nanoscale, offer innovative antibacterial modalities not present in traditional defensive mechanisms. This comprehensive review focuses on the potential of nanotechnology in combating biofilms, focusing on green-synthesized nanoparticles and their associated anti-biofilm potential. The review encompasses various aspects of nanoparticle-mediated biofilm inhibition, including mechanisms of action. The diverse mechanisms of action of green-synthesized nanoparticles offer valuable insights into their potential applications in addressing AMR and improving treatment outcomes, highlighting novel strategies in the ongoing battle against infectious diseases.

Photocatalytic Bacterial Destruction and Mineralization by TiO2-Based Photocatalysts: A Mini Review

This work presents an overview of the reports on the bacterial cell photocatalytic destruction and mineralization process in the presence of TiO2-based photocatalysts. The presented research included experiments conducted in air and water. Numerous works confirmed that a photocatalytic process with TiO2 led to bacteria and their organic residues' mineralization. Additionally, based on the obtained results, a possible two-stage mechanism of photocatalytic mineralization in the presence of TiO2-based materials was proposed. To help future studies, challenges of photocatalytic microorganism mineralization are also proposed. There are some aspects that need to be addressed, such as the lack of standardization of conducted research or relatively small amount of research on photocatalytic microorganism mineralization. According to our best knowledge, in the available literature, no work regarding a summary of previous research on photocatalytic bacterial mineralization process was found.

Recent Advancements and Unexplored Biomedical Applications of Green Synthesized Ag and Au Nanoparticles: A Review

Green synthesis of silver (Ag) and gold (Au) nanoparticles (NPs) has acquired huge popularity owing to their potential applications in various fields. A large number of research articles exist in the literature describing the green synthesis of Ag and Au NPs for biomedical applications. However, these findings are scattered, making it time-consuming for researchers to locate promising advancements in Ag and Au NPs synthesis and their unexplored biomedical applications. Unlike other review articles, this systematic study not only highlights recent advancements in the green synthesis of Ag and Au NPs but also explores their potential unexplored biomedical applications. The article discusses the various synthesis approaches for the green synthesis of Ag and Au NPs highlighting the emerging developments and novel strategies. Then, the article reviews the important biomedical applications of green synthesized Ag and Au NPs by critically evaluating the expected advantages. To expose future research direction in the field, the article describes the unexplored biomedical applications of the NPs. Finally, the articles discuss the challenges and limitations in the green synthesis of Ag and Au NPs and their biomedical applications. This article will serve as a valuable reference for researchers, working on green synthesis of Ag and Au NPs for biomedical applications.

Fabrication of Poly(Lactic Acid)@TiO2 Electrospun Membrane Decorated with Metal-Organic Frameworks for Efficient Air Filtration and Bacteriostasis

The development of high-performance filtration materials is essential for the effective removal of airborne particles, and metal-organic frameworks (MOFs) anchored to organic polymer matrices are considered to be one of the most promising porous adsorbents for air pollutants. Nowadays, most air filters are generally based on synthetic fiber polymers derived from petroleum residues and have limited functionality, so the use of MOFs in combination with nanofiber air filters has received a lot of attention. Here, a conjugated electrostatic spinning method is demonstrated for the one-step preparation of poly(lactic acid) (PLA) nanofibrous membranes with a bimodal diameter distribution and the anchoring of Zeolitic Imidazolate Framework-8 (ZIF-8) by the introduction of TiO2 and in situ generation to construct favorable multiscale fibers and rough structures. The prepared PLA/TZ maintained a good PM2.5 capture efficiency of 99.97%, a filtration efficiency of 96.43% for PM0.3, and a pressure drop of 96.0 Pa, with the highest quality factor being 0.08449 Pa-1. Additionally, ZIF-8 was uniformly generated on the surface of PLA and TiO2 nanofibers, obtaining a roughened structure and a larger specific surface area. An enhanced filtration retention effect and electrostatic interactions, as well as active free radicals, can be generated for the deep inactivation of bacteria. Compared with the unmodified membrane, PLA/TZ prepared antibacterial characteristics induced by photocatalysis and Zn2+ release, with excellent bactericidal effects against S. aureus and E. coli. Overall, this work may provide a promising approach for the development of efficient biomass-based filtration materials with antimicrobial properties.

Combinational antimicrobial activity of biogenic TiO2 NP/ZnO NPs nanoantibiotics and amoxicillin-clavulanic acid against MDR-pathogens

The development of effective strategies against multidrug-resistant (MDR) pathogens is an urgent need in modern medicine. Nanoantibiotics (nABs) offer a new hope in countering the surge of MDR-pathogens. The aim of the current study was to evaluate the antibacterial activity of two attractive nABs, TiO2 NPs and ZnO NPs, and their performance in improving the antimicrobial activity of defined antibiotics (amoxicillin-clavulanic acid, amox-clav) against MDR-pathogens. The nABs were synthesized using a green method. The physicochemical characteristics of the synthesized nanoparticles were determined using standard methods. The results showed the formation of pure anatase TiO2 NPs and hexagonal ZnO NPs with an average particle size of 38.65 nm and 57.87 nm, respectively. The values of zeta potential indicated the high stability of the samples. At 8 mg/mL, both nABs exhibited 100 % antioxidant activity, while ZnO showed significantly higher activity at lower concentrations. The antibiofilm assay showed that both nABs could inhibit the formation of biofilms of Acinetobacter baumannii 80 and Escherichia coli 27G (MDR-isolates). However, ZnO NPs showed superior antibiofilm activity (100 %) against E. coli 27G. The MIC values were determined to be 8 (1), 2 (2), and 4 (4) mg/mL for amox-clav, TiO2 NPs, and ZnO NPs against A. baumannii 80 (E. coli 27G), respectively. The results showed that both nABs had synergistically enhanced antibacterial performance in combination with amox-clav. Specifically, an 8-fold reduction in MIC values of antibiotics was observed when they were combined with nABs. These findings highlight the potential of TiO2 NPs and ZnO NPs as effective nanoantibiotics against MDR-pathogens. The synergistic effect observed when combining nABs with antibiotics suggests a promising approach for combating antibiotic resistance. Further research and development in this area could lead to the development of more effective treatment strategies against MDR infections.

Recent advances in the use of composite titanium dioxide nanomaterials in the food industry

Titanium dioxide (TiO2 ) nanomaterials have attracted significant attention due to their good biocompatibility and potential for multifunctional applications. In the last few years, there has been growing interest in the use of TiO2 nanomaterials in the food industry. However, a systematic review of the synthesis methods, properties, and applications of TiO2 nanomaterials in the food industry is lacking. In this review, we provide a summary of the synthesis and properties of TiO2 nanomaterials and their composites, with a focus on their applications in the food industry. We also discuss the potential benefits and risks of using TiO2 nanomaterials in food applications. This review aims to promote food innovation and improve food quality and safety.

Revisiting the smart metallic nanomaterials: advances in nanotechnology-based antimicrobials

Despite significant advancements in diagnostics and treatments over the years, the problem of antimicrobial drug resistance remains a pressing issue in public health. The reduced effectiveness of existing antimicrobial drugs has prompted efforts to seek alternative treatments for microbial pathogens or develop new drug candidates. Interestingly, nanomaterials are currently gaining global attention as a possible next-generation antibiotics. Nanotechnology holds significant importance, particularly when addressing infections caused by multi-drug-resistant organisms. Alternatively, these biomaterials can also be combined with antibiotics and other potent biomaterials, providing excellent synergistic effects. Over the past two decades, nanoparticles have gained significant attention among research communities. Despite the complexity of some of their synthesis strategies and chemistry, unrelenting efforts have been recorded in synthesizing potent and highly effective nanomaterials using different approaches. With the ongoing advancements in nanotechnology, integrating it into medical procedures presents novel approaches for improving the standard of patient healthcare. Although the field of nanotechnology offers promises, much remains to be learned to overcome the several inherent issues limiting their full translation to clinics. Here, we comprehensively discussed nanotechnology-based materials, focusing exclusively on metallic nanomaterials and highlighting the advances in their synthesis, chemistry, and mechanisms of action against bacterial pathogens. Importantly, we delve into the current challenges and prospects associated with the technology.

Biogenic Punica granatum Flower Extract Assisted ZnFe2O4 and ZnFe2O4-Cu Composites for Excellent Photocatalytic Degradation of RhB Dye

Globally, the textile industry contributes to pollution through accidental discharges or discharge of contaminated wastewater into waterways, significantly affecting water quality. These pollutants, including dye molecules, are environmental hazards for aquatic and terrestrial life. The field of visible light-mediated photocatalysis has experienced rapid growth, driven by the utilization of photocatalysts that can absorb low-energy visible light and effectively degrade dyes. In the present study, we report a simple method to controllably synthesize Fe2O3, ZnO, and ZnFe2O4 using the one-pot synthesis method. In the subsequent step, copper (Cu) was deposited on the surface of ZnFe2O4 (forming ZnFe2O4-Cu) using a facile, green, and cost-effective method. The synthesized samples were characterized using various techniques, including XRD, UV-Vis DRS, FT-IR, SEM-EDX, HR-TEM, XPS, PL, and BET analysis. These techniques were employed to investigate the composition, morphology, structure, and photophysical properties of as-prepared samples. The ZnFe2O4-Cu nanocomposite demonstrated efficient photocatalytic activity for degrading RhB dye pollutants under visible light. The photocatalyst was successfully reused for three consecutive cycles without significantly decreasing performance. Furthermore, during the study, the radical scavenging test emphasized the role of different radicals in the degradation of dye pollutants. This research has the potential to enable the efficient production of high-performance photocatalysts that can rapidly eliminate ecologically harmful dyes from aqueous solutions.

Pure Epigallocatechin-3-gallate-Assisted Green Synthesis of Highly Stable Titanium Dioxide Nanoparticles

Nanoparticles (NPs) are conventionally produced by using physical and chemical methods that are no longer in alignment with current society's demand for a low environmental impact. Accordingly, green synthesis approaches are considered a potential alternative due to the plant extracts that substitute some of the hazardous reagents. The general mechanism is based on the reducing power of natural products that allows the formation of NPs from a precursor solution. In this context, our study proposes a simple, innovative, and reproducible green approach for the synthesis of titanium dioxide (TiO2 NPs) that uses, for the first time, the major component of green tea (Camellia sinensis)-epigallocatechin-3-gallate (EGCG), a non-toxic, dietary, accessible, and bioactive molecule. The influence of EGCG on the formation of TiO2 NPs was analyzed by comparing the physicochemical characteristics of green synthesized NPs with the chemically obtained ones. The synthesis of bare TiO2 NPs was performed by hydrolysis of titanium isopropoxide in distilled water, and green TiO2 NPs were obtained in the same conditions, but in the presence of a 1 mM EGCG aqueous solution. The formation of TiO2 NPs was confirmed by UV-VIS and FTIR spectroscopy. SEM micrographs showed spherical particles with relatively low diameters. Our findings also revealed that green synthesized NPs were more stable in colloids than the chemically synthesized ones. However, the phytocompound negatively influenced the formation of a crystalline structure in the green synthesized TiO2 NPs. Furthermore, the synthesis of EGCG-TiO2 NPs could become a versatile choice for applications extending beyond photocatalysis, including promising prospects in the biomedical field.

Bacterial nano-factories as a tool for the biosynthesis of TiO2 nanoparticles: characterization and potential application in wastewater treatment

The development of reliable and eco-conscious processes for nanoparticle synthesis constitutes a significant element in nanotechnology. TiO2 nanoparticles (NPs) are becoming essential due to their potential uses in dentistry, surgery, agriculture, and pharmacy. This leads to the development of various procedures for producing TiO2 NPs using various physicochemical methods. Still, the drawbacks of these conventional methods are associated with the emission of toxic chemicals into the atmosphere and high energy demands in production, hence endangering the health and the environment. Problems issued are solved by green nanotechnology, which offers tools as nano-factories by utilizing biological sources to subside the improper effects of conventional methods and produces nanoparticles through synthesis methods that are clean, safe, energy-efficient, and cost-effective. Among the biogenic sources, microbial cells such as bacteria possess intrinsic pathways of converting metallic salt to nanoparticles due to their ability to produce reductase enzymes. Also, they can offer features to products such as high dispersity and produce sustainable nanoparticles at a large scale. Biosynthesized TiO2 NPs have high oxidizing potential and a wide range of applications, specifically as photosensitizers and antimicrobial agents. This review will address bacterial nano-factories that can be utilized for the biosynthesis of TiO2 NPs, the characterization of biosynthesized nanoparticles, and their potential application in wastewater treatment.

Microbial synthesis of titanium dioxide nanoparticles and their importance in wastewater treatment and antimicrobial activities: a review

Nanotechnology (NT) and nanoparticles (NPs) have left a huge impact on every field of science today, but they have shown tremendous importance in the fields of cosmetics and environmental cleanup. NPs with photocatalytic effects have shown positive responses in wastewater treatment, cosmetics, and the biomedical field. The chemically synthesized TiO2 nanoparticles (TiO2 NPs) utilize hazardous chemicals to obtain the desired-shaped TiO2. So, microbial-based synthesis of TiO2 NPs has gained popularity due to its eco-friendly nature, biocompatibility, etc. Being NPs, TiO2 NPs have a high surface area-to-volume ratio in addition to their photocatalytic degradation nature. In the present review, the authors have emphasized the microbial (algae, bacterial, fungi, and virus-mediated) synthesis of TiO2 NPs. Furthermore, authors have exhibited the importance of TiO2 NPs in the food sector, automobile, aerospace, medical, and environmental cleanup.

Syzygium cumini (L.) Extract-Derived Green Titanium Dioxide Nanoparticles Induce Caspase-Dependent Apoptosis in Hepatic Cancer Cells

An aqueous extract of Syzygium cumini seeds was utilized to green synthesize titanium dioxide nanoparticles (TiO2 NPs). UV-Visible, DLS, FTIR, XRD, FESEM, TEM, SAED, EDAX, and photoluminescence spectroscopy techniques were employed to characterize the prepared TiO2 nanoparticles. The rutile crystal structure of TiO2 NPs was revealed by XRD study. The TEM and FESEM images of the TiO2 NPs revealed an average particle size of 50-100 nm. We employed EDAX to investigate the elemental compositions of TiO2 NPs. The O-Ti-O stretching bands appeared in the FTIR spectrum of TiO2 NPs at wavenumbers of 495 cm-1. The absorption edge peaks of TiO2 NPs were found in the UV-vis spectra at 397 nm. The MTT study revealed that TiO2 NPs effectively inhibited the growth of liver cancer Hep3 and Hep-G2 cells. The results of the corresponding fluorescent staining assays showed that TiO2 NPs significantly increased ROS generation, decreased MMP, and induced apoptosis in both liver cancer Hep3 and Hep-G2 cells. TiO2 nanoparticles lessened SOD, CAT, and GSH levels while augmenting MDA contents in Hep3 and Hep-G2 cells. In both Hep3 and Hep-G2 cells treated with TiO2 NPs, the Bax, CytC, p53, caspase-3, -8, and -9 expressions were remarkably augmented, while Bcl-2 expression was reduced. Overall, these findings revealed that formulated TiO2 NPs treatment considerably inhibited growth and triggered apoptosis in Hep3 and HepG2 cells.

Electrospun silk nanofiber loaded with Ag-doped TiO2 with high-reactive facet as multifunctional air filter

Particulate matter (PM) and volatile organic compounds (VOCs) are air pollution that can cause high risk to public health. To protect individuals from air pollution exposure, fibrous filters have been widely employed. In this work, we develop silk nanofibers, which are loaded with Ag-doped TiO2 nanoparticles with exposed (001) (assigned as Ag-TiO2-silk), via electrospinning method and utilized them as multifunctional air filters that can efficiently reduce PM2.5, organic pollutants and microbials. The results showed that Ag-TiO2-silk with a loading of 1 wt% (1%Ag-TiO2-silk) exhibited the best performance among various different Ag-doped samples, as it performed the best as an air filter, which had the highest PM2.5 removal efficiency of 99.04 ± 1.70% with low pressure drop of 34.3 Pa, and also exhibited the highest photodegradation efficiency of formaldehyde. In addition, the Ag-TiO2-silk demonstrated antibacterial activity. These properties make silk composite nanofibers attractive for multifunctional and environmentally-friendly air filter application.

Green and sustainable synthesis of nanomaterials: Recent advancements and limitations

Nanomaterials have been widely used in diverse fields of research such as engineering, biomedical science, energy, and environment. At present, chemical and physical methods are the main methods for large-scale synthesis of nanomaterials, but these methods have adverse effects on the environment, and health issues, consume more energy, and are expensive. The green synthesis of nanoparticles is a promising and environmentally friendly approach to producing materials with unique properties. Natural reagents such as herbs, bacteria, fungi, and agricultural waste are used in the green synthesis of nanomaterials instead of hazardous chemicals and reduce the carbon footprint of the synthesis process. Green synthesis of nanomaterials is highly beneficial compared to traditional methods due to its low cost, negligible pollution level, and safety for the environment and human health. Nanoparticles possess enhanced thermal and electrical conductivity, catalytic activity, and biocompatibility, making them highly attractive for a range of applications, including catalysis, energy storage, optics, biological labeling, and cancer therapy. This review article provides a comprehensive overview of recent advancements in the green synthesis routes of different types of nanomaterials, including metal oxide-based, inert metal-based, carbon-based, and composite-based nanoparticles. Moreover, we discuss the various applications of nanoparticles, emphasizing their potential to revolutionize fields such as medicine, electronics energy, and the environment. The factors affecting the green synthesis of nanomaterials, and their limitations are also pointed out to decide the direction of this research field, Overall, this paper highlights the importance of green synthesis in promoting sustainable development in various industries.

An Eco-Friendly Approach Utilizing Green Synthesized Titanium Dioxide Nanoparticles for Leather Conservation against a Fungal Strain, Penicillium expansum AL1, Involved in the Biodeterioration of a Historical Manuscript

The main hypothesis of the present research is investigating the efficacy of titanium oxide nanoparticles (TiO₂-NPs) to prevent the growth of fungal strains when applied on leather under an experimental study. Therefore, fifteen fungal strains were isolated from a deteriorated historical manuscript (papers and leathers) and identified by traditional methods and ITS sequence analysis, including Aspergillus chevalieri (one isolate), A. nidulans (two strains), A. flavus (four strains), A. cristatus (one strain), A. niger (one strain), Paecilomyces fulvus (two strains), Penicillium expansum (two strains), and P. citrinum (two strains). The enzymes cellulase, amylase, pectinase, and gelatinase, which play a crucial role in biodegradation, were highly active in these fungal strains. TiO₂-NPs were formed using the cell-free filtrate of the probiotic bacterial strain, Lactobacillus plantarum, and characterized. Data showed that the TiO₂-NPs were successfully formed with a spherical shape and anatase phase with sizes of 2-8 nm. Moreover, the EDX analysis revealed that the Ti and O ions occupied the main component with weight percentages of 41.66 and 31.76%, respectively. The in vitro cytotoxicity of TiO₂-NPs toward two normal cell lines, WI38 and HFB4, showed a low toxicity effect against normal cells (IC₅₀ = 114.1 ± 8.1µg mL^-1 for Wi38, and 237.5 ± 3.5µg mL^-1 for HFB4). Therefore, concentrations of 100 μg mL^-1 were used to load on prepared leather samples before inoculation with fungal strain P. expansum AL1. The experimental study revealed that the loaded TiO₂-NPs have the efficacy to inhibit fungal growth with percentages of 73.2 ± 2.5%, 84.2 ± 1.8%, and 88.8 ± 0.6% after 7, 14, and 21 days, respectively. Also, the analyses including SEM, FTIR-ART, color change, and mechanical properties for leather inoculated with fungal strain AL1 in the absence of NPs showed high damage aspects compared to those inoculated with fungal strains in the presence of TiO₂-NPs.

Biosynthesis approach of copper nanoparticles, physicochemical characterization, cefixime wastewater treatment, and antibacterial activities

The aim of this paper is the green synthesis of copper nanoparticles (Cu NPs) via Quinoa seed extract. X-ray diffraction (XRD) results confirmed the production of the pure crystalline face center cubic system of the Cu NPs with an average crystallite size of 8.41 nm. Infrared spectroscopy (FT-IR) analysis confirmed the capping and stabilization of the Cu NPs bioreduction process. UV visible spectroscopy (UV-Vis). surface plasmon resonance revealed the absorption peak at 324 nm with an energy bandgap of 3.47 eV. Electrical conductivity was conducted assuring the semiconductor nature of the biosynthesized Cu NPs. Morphological analysis was investigated confirming the nano-characteristic properties of the Cu NPs as polycrystalline cubic agglomerated shapes in scanning electron microscopy (SEM) analysis. Transmission electron microscopy (TEM) analysis also was used to assess the cubic shapes at a particle size of 15.1 ± 8.3 nm and a crystallinity index about equal to 2.0. Energy dispersive spectroscopy (EDX) was conducted to investigate the elemental composition of the Cu NPs. As a potential utility of the biosynthesized Cu NPs as nano adsorbents to the removal of the Cefixime (Xim) from the pharmaceutical wastewater; adsorption studies and process parameters were being investigated. The following strategic methodology for maximum Xim removal was conducted to be solution pH 4, Cu NPs dosage 30 mg, Xim concentration 100 mg/L, and absolute temperature 313 K. The maximum monolayer adsorption capacity was 122.9 mg/g according to the Langmuir isothermal model, and the kinetic mechanism was pseudo-second-order. Thermodynamic parameters also were derived as spontaneous chemisorption endothermic processes. Antibacterial activity of the Xim and Xim@Cu NPs was investigated confirming they are highly potent against each Gram-negative and Gram-positive bacterium.

Synthesis, characterization and antifungal potential of titanium dioxide nanoparticles against fungal disease (Ustilago tritici) of wheat (Triticum aestivum L.)

Nanoparticles (NPs) preparation using a green as well as environmentally acceptable processes has achieved a lot of attention in recent decade. The current study compared the synthesis of titania (TiO₂) nanoparticles synthesized from leaf extracts of two plant species (Trianthema portulacastrum, Chenopodium quinoa) and traditional approach by chemical preparation. The effects of no calcination on the physical characteristics of TiO₂ NPs as well as their antifungal effects were examined and compared with the already reported calcinated TiO₂ NPs. The produced TiO₂ NPs were evaluated using high-tech techniques such as X-ray diffraction (XRD), scanning electron microscope, energy dispersive spectroscopy (EDX), and elemental mapping. TiO₂ NPs prepared by sol-gel technique (T1) and prepared from extractions from leaves of T. portulacastrum (T2), and C. quinoa (T3) were either calcinated or non calcinated and tested against fungal disease (Ustilago tritici) of wheat for antifungal efficacy. The -peak (2θ) at 25.3 was confirmed by XRD to be connected with the anatase (101) form in both cases but before calcination, NPs were lacking the rutile and brookite peaks. The results showed that all types of TiO₂ NPs examined had good antifungal activity against U. tritici, but those made from C. quinoa plant extract have good antifungal activity against disease. TiO₂ NPs which are produced by the green methods (T2, T3) have the highest antifungal activity (58%, 57% respectively), while minimal activity (19%) was recorded when NPs were synthesized using the sol-gel method (T1) with 25 μl/mL. Non calcinated TiO₂ NPs have less antifungal potential than calcined TiO₂ NPs. It can be concluded that calcination may be preferred for efficient antifungal activity when using titania nanoparticles. The green technology may be used on a larger scale with less damaging TiO₂ NP production and can be utilized against fungal disease on wheat crop to reduce crop losses worldwide.

Updates on Biogenic Metallic and Metal Oxide Nanoparticles: Therapy, Drug Delivery and Cytotoxicity

The ambition to combat the issues affecting the environment and human health triggers the development of biosynthesis that incorporates the production of natural compounds by living organisms via eco-friendly nano assembly. Biosynthesized nanoparticles (NPs) have various pharmaceutical applications, such as tumoricidal, anti-inflammatory, antimicrobials, antiviral, etc. When combined, bio-nanotechnology and drug delivery give rise to the development of various pharmaceutics with site-specific biomedical applications. In this review, we have attempted to summarize in brief the types of renewable biological systems used for the biosynthesis of metallic and metal oxide NPs and the vital contribution of biogenic NPs as pharmaceutics and drug carriers simultaneously. The biosystem used for nano assembly further affects the morphology, size, shape, and structure of the produced nanomaterial. The toxicity of the biogenic NPs, because of their pharmacokinetic behavior in vitro and in vivo, is also discussed, together with some recent achievements towards enhanced biocompatibility, bioavailability, and reduced side effects. Because of the large biodiversity, the potential biomedical application of metal NPs produced via natural extracts in biogenic nanomedicine is yet to be explored.

Metal Oxide Nanostructures (MONs) as Photocatalysts for Ciprofloxacin Degradation

In recent years, organic pollutants have become a global problem due to their negative impact on human health and the environment. Photocatalysis is one of the most promising methods for the removal of organic pollutants from wastewater, and oxide semiconductor materials have proven to be among the best in this regard. This paper presents the evolution of the development of metal oxide nanostructures (MONs) as photocatalysts for ciprofloxacin degradation. It begins with an overview of the role of these materials in photocatalysis; then, it discusses methods of obtaining them. Then, a detailed review of the most important oxide semiconductors (ZnO, TiO₂, CuO, etc.) and alternatives for improving their photocatalytic performance is provided. Finally, a study of the degradation of ciprofloxacin in the presence of oxide semiconductor materials and the main factors affecting photocatalytic degradation is carried out. It is well known that antibiotics (in this case, ciprofloxacin) are toxic and non-biodegradable, which can pose a threat to the environment and human health. Antibiotic residues have several negative impacts, including antibiotic resistance and disruption of photosynthetic processes.

Individual and binary exposure to nanoscales of silver, titanium dioxide, and silicon dioxide alters viability, growth, and reproductive system: Hidden indices to re-establish artemia as a toxicological model in saline waters

This study evaluated and compared the individual and combined toxicity of AgNPs, TiO₂NPs, and SiO₂NPs to life cycle of A. salina. To this end, both stability and toxicity of AgNPs were determined in the presence of TiO₂NPs and SiO₂NPs. The colloidal stability of AgNPs decreased in the presence of the other two NPs, especially SiO₂NPs. AgNPs displayed acute toxicity to A. salina, whereas SiO₂NPs and TiO₂NPs chronically induced toxicity in a concentration- and time-dependent manner during 28-day exposure. The experimental NPs significantly decreased the weight and length of A. salina and induced reproductive toxicity through perturbation in first brood timespan, sexual maturity, egg development time, egg pouch area, offspring quality, and fecundity. Exposure to AgNPs shifted the mode of reproduction in brine shrimp from ovoviviparity to oviparity, and also co-presence of AgNPs with SiO₂NPs or TiO₂NPs caused infertility. Generally, their individual toxicity was in order of AgNPs > TiO₂NPs > SiO₂NPs, and binary exposure to AgNPs-SiO₂NPs appear to be more threatening than AgNPs-TiO₂NPs to A. salina. Together, this study highlights that these nanoparticles could disrupt reproductive health of A. salina and lead to alterations in population dynamics and aquatic ecosystem balance.

Biogenic silver based nanostructures: Synthesis, mechanistic approach and biological applications

The alarming impact of antibiotic resistance sparked the quest for complementary treatments to overcome the confrontation over resistant pathogens. Metallic nanoparticles, especially silver nanoparticles (Ag NPs) have gained a much attention because of their remarkable biological characteristics. Moreover, their medicinal properties can be enhanced by preparing the composites with other materials. This article delves a comprehensive review of biosynthesis route for Ag NPs and their nanocomposites (NCs) with in-depth mechanism, methods and favorable experimental parameters. Comprehensive biological features Ag NPs such as antibacterial, antiviral, antifungal have been examined, with a focus on their potential uses in biomedicine and diagnostics has also been discussed. Additionally, we have also explored the hitches and potential outcomes of biosynthesis of Ag NPs in biomedical filed.

Recent advances in nanomaterials based sustainable approaches for mitigation of emerging organic pollutants

Emerging organic pollutants (EOPs) are a category of pollutants that are relatively new to the environment and recently garnered a lot of attention. The majority of EOPs includes endocrine-disrupting chemicals (EDCs), antibiotic resistance genes (ARGs), pesticides, dyes and pharmaceutical and personal care products (PPCPs). Exposure to contaminated water has been linked to an increase in incidences of malnutrition, intrauterine growth retardation, respiratory illnesses, liver malfunctions, eye and skin diseases, and fatalities. Consequently, there is a critical need for wastewater remediation technologies which are effective, reliable, and economical. Conventional wastewater treatment methods have several shortcomings that can be addressed with the help of nanotechnology. Unique characteristics of nanomaterials (NMs) make them intriguing and efficient alternative in wastewater treatment strategies. This review emphasis on the occurrence of divers emerging organic pollutants (EOPs) in water and their effective elimination via different NMs based methods with in-depth mechanisms. Furthermore, it also delves the toxicity assessment of NMs and critical challenges, which are crucial steps for practical implementations.

Dynamic Light Scattering: A Powerful Tool for In Situ Nanoparticle Sizing

Due to surface effects and quantum size effects, nanomaterials have properties that are vastly different from those of bulk materials due to surface effects. The particle size distribution plays an important role in chemical and physical properties. The measurement and control of this parameter are crucial for nanomaterial synthesis. Dynamic light scattering (DLS) is a fast and non-invasive tool used to measure particle size, size distribution and stability in solutions or suspensions during nanomaterial preparation. In this review, we focus on the in situ sizing of nanomaterial preparation in the form of colloids, especially for metal oxide nanoparticles (MONs). The measuring principle, including an overview of sizing techniques, advantages and limitations and theories of DLS were first discussed. The instrument design was then investigated. Ex-situ and in situ configuration of DLS, sample preparations, measurement conditions and reaction cell design for in situ configuration were studied. The MONs preparation monitored by DLS was presented, taking into consideration both ex situ and in situ configuration.

Sustainable synthesis of biogenic ZnO NPs for mitigation of emerging pollutants and pathogens

Groundwater pollution is mostly caused by overuse of fertilizers, pesticides, contemporary agricultural practices, anthropogenic activities, home waste disposal, and the rapid expansion of the chemical industry. Drinking tainted water on a regular basis can have detrimental consequences on human health as well on environment. Nanoparticles (NPs) based contaminants alleviation strategy found to be most efficient, cost-effective and reliable. In this study, ZnO NPs were synthesized via citrus limon leaves extract as a sustainable/cost-effective method. Diverse microscopic and spectroscopic studies confirmed the formation of spherical ZnO NPs with size range 15-25 nm. Reactive green-19 (RG-19) was degraded photocatalytically under direct solar irradiation (degradation efficiency ∼ 92%, rate constant 0.03 min ^-1, 80 min) in the presence of ZnO NPs. These ZnO NPs also demonstrated highly substantial antibacterial action against two pathogenic Gram-positive (Bacillus subtilis, zone of clearance: 8.6 mm) and Gram-negative (Escherichia coli, zone of clearance: 9.8 mm) bacteria. Thus, the present study demonstrates the effective/sustainable NPs based platform for water remediation.

Poly(butylene adipate-co-terephthalate)/Poly(lactic acid) Polymeric Blends Electrospun with TiO2-R/Fe3O4 for Pollutant Photodegradation

This work aimed to use the electrospinning technique to obtain PBAT/PLA polymer fibers, with the semiconductors rutile titanium dioxide (TiO₂-R) and magnetite iron oxide (Fe₃O₄), in order to promote the photocatalytic degradation of environmental contaminants. The parameters used in the electrospinning process to obtain the fibers were distance from the needle to the collecting target of 12 cm, flow of 1 mL h^-1 and voltage of 14 kV. The best mass ratio of semiconductors in the polymeric fiber was defined from a 2² experimental design, and the values obtained were 10% TiO₂-R, 1% Fe₃O₄ at pH 7.0. Polymer fibers were characterized by Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and Fourier Transform Infrared (FTIR) techniques. SEM measurements indicated a reduction in fiber diameter after the incorporation of semiconductors; for the PBAT/PLA fiber, the average diameter was 0.9466 ± 0.2490 µm, and for the fiber with TiO₂-R and Fe₃O₄ was 0.6706 ± 0.1447 µm. In the DSC, DRX, TGA and FTIR analyses, it was possible to identify the presence of TiO₂-R and Fe₃O₄ in the fibers, as well as their interactions with polymers, demonstrating changes in the crystallinity and degradation temperature of the material. These fibers were tested against Reactive Red 195 dye, showing an efficiency of 64.0% within 24 h, showing promise for photocatalytic degradation of environmental contaminants.

ZnO and cobalt decorated ZnO NPs: Synthesis, photocatalysis and antimicrobial applications

The rapid growth of pollutants, both biological and non-biological, puts environmental systems in jeopardy. In view of this, the current study demonstrates the synthesis of undoped and Cobalt-doped zinc oxide nanoparticles (Co doped ZnO NPs) via co-precipitation method. The confirmation of incorporation of the Co dopant into ZnO NPs was verified through various spectroscopic and microscopic techniques. UV-absorption spectra of cobalt-doped ZnO NPs revealed a red shift with change of absorption spectra from 356 nm to 377 nm as compared to undoped ZnO NPs. XRD studies inferred that the average crystallite size of 0.5% and 1% Co-doped ZnO powder was obtained to be ∼16 nm and 14 nm respectively. A drop in band gap value from 3.48 eV to 3.30 eV provided as substantive evidence of the successful integration of Co²⁺ ions inside the ZnO matrix. FESEM and HRTEM studies revealed that the obtained ZnO NPs are in narrow size distribution (15-20 nm) with a wurtzite crystal structure. The synthesized ZnO and Co-ZnO NPs showed excellent photocatalytic and antimicrobial potency towards reactive brown dye (RB-1) and two bacterial strains, respectively. 1% Co-doped ZnO demonstrated the maximum photocatalytic activity (∼95%), in contrast to 0.5% Co-doped ZnO and undoped ZnO. Thus, the findings of this work support the developed system has a dual role as the photocatalyst, and antibacterial agent for efficient environmental remediation.

Recent advances in green synthesized nanoparticles for bactericidal and wound healing applications

Nanotechnology has become an exciting area of research in diverse fields, such as: healthcare, food, agriculture, cosmetics, paints, lubricants, fuel additives and other fields. This review is a novel effort to update the practioneers about the most current developments in the widespread use of green synthesized nanoparticles in medicine. Biosynthesis is widely preferred among different modes of nanoparticle synthesis since they do not require toxic chemical usage and they are environment-friendly. In the green bioprocess, plant, algal, fungal and cyanobacterial extract solutions have been utilized as nucleation/capping agents to develop effective nanomaterials for advanced medical applications. Several metal salts, such as silver, zinc, titanium and other inorganic salts, were utilized to fabricate innovative nanoparticles for healthcare applications. Irrespective of the type of wound, infection in the wound area is a widespread problem. Micro-organisms, the prime reason for wound complications, are gradually gaining resistance against the commonly used antimicrobial drugs. This necessitates the need to generate nanoparticles with efficient antimicrobial potential to keep the pathogenic microbes under control. These nanoparticles can be topically applied as an ointment and also be used by incorporating them into hydrogels, sponges or electrospun nanofibers. The main aim of this review is to highlight the recent advances in the Ag, ZnO and TiO₂ nanoparticles with possible wound healing applications, coupled with the bactericidal ability of a green synthesis process.

Synthesis of TiO2, TiO2/PAni, TiO2/PAni/GO nanocomposites and photodegradation of anionic dyes Rose Bengal and thymol blue in visible light

Nowadays, fast-growing industrialization has resulted in the release of enormous amounts of contaminants such as toxic dyes into water bodies and leading to cause health and environmental risks. In this regard, we prepared inorganic nanocomposites for the treatment of toxic dyes. Hence, we synthesized TiO₂/PAni/GO nanocomposites and examined them by using XRD, SEM, TEM, UV-Vis spectroscopy, BET analysis, and a photoluminescence investigation. In addition, band gap energies of the nanocomposites were determined, and Total Organic Carbon (TOC) testing was used to determine dye degradation levels. The photocatalytic degradations of Thymol Blue and Rose Bengal dyes were investigated at different dye concentrations, illumination periods, solution pH values, and photocatalyst dosages. By using TiO₂/PAni/GO, TiO₂/PAni, and TiO₂ at neutral pH, a photocatalyst dose of 1600 mg/L, and exposure to visible light, Thymol Blue and Rose Bengal were photodegraded 85-99%, 60-97%, and 10-20%, respectively, at a concentration of 25 ppm (180 min). Reductions in the TOCs confirmed their photodegradation, and a kinetic study revealed photodegradation followed first-order kinetics. This study shows the coating of polyaniline (PAni) and graphene oxide (GO) on TiO₂ improved its ability to photodegrade Thymol Blue and Rose Bengal dye.

Phytochemical-assisted Synthesis of Titania Nanoparticles using Azadirachta indica Leaf Extract as Photocatalyst in the Photodegradation of Methyl Orange

The biosynthesis procedure for nanomaterial preparation is a promising alternative due to its simplicity and environmental friendliness. In this work, TiO2 NPs were biosynthesized using the aqueous leaf extract of Azadirachta indica. The influence of the extract volumes, solvents, and acetic acid on the properties of TiO2 NPs was studied. Phytochemical screening and ATR-FTIR spectrum confirmed the presence of phenolic compounds in the leaf extract. XRD patterns showed that the samples were mainly in the anatase phase. However, for the water-based samples and when 1 and 2 mL of extract volumes were used, anatase/brookite mixture was observed. FESEM images displayed almost spherical and agglomerated NPs. UV-Vis-NIR studies showed that the samples’ bandgaps values are within the range of anatase TiO2. The photocatalytic activity of the TiO2 NPs was evaluated in the photodegradation of methyl orange (MO) under UV light irradiation. The water-based sample synthesized using 2 mL of the extract achieved 98.62% of MO degradation within 270 min and demonstrated the highest pseudo-first-order photodegradation kinetic constant of 0.0147 min-1. These results indicate that the use of the plant-based biosynthesis method with water as the solvent successfully produced TiO2 NPs with good physicochemical properties and photocatalytic activity in the photodegradation of organic dye. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Green route synthesis and characterization of β-Bi2O3/SiO2 and β-Bi2O3/Bi2O2.75/SiO2 using Juglans regia L. shell aqueous extract and photocatalytic properties for the degradation of RB-5

Background

Photocatalyst oxides added with silicon improve their photocatalytic properties. In this research, nanostructured β-Bi2O3/SiO2 and β-Bi2O3/Bi2O2.75/SiO2 were obtained by means of a green method mediated by the using the aqueous extract of J. regia shell as the source of reducing biomolecules and as a natural source of plant silicon.

Method

The β-Bi2O3/SiO2 and β-Bi2O3/Bi2O2.75/SiO2 nanostructures were characterized by Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy (HR-TEM), field emission scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), and photoluminescence spectroscopy. The photocatalytic activity was measured by the degradation of Reactive Black 5 dye (RB-5).

Results

FT-IR and XPS demonstrated the presence of plant silicon in the bismuth oxide photocatalysts. HR-TEM showed that the crystal size of the as-synthesized materials is ~ 25 nm and revealed that the β-Bi2O3 synthesized with ground shell extract and heat-treated at 300 °C contains the Bi2O2.75 phase. Good photocatalytic activity was found in all the studied materials; particularly, the heat-treated nanostructures showed excellent properties resulting in 92% degradation of RB-5 under UV–Vis light after 15 min of exposure, and 98% after 180 min.

Conclusions

The findings of this research suggest that the metabolites coating the Bi2O3, which generate a large amount of hydroxyl radicals, the plant silicon content, and the crystalline defects conferred by the synthesis medium, all contribute to the improved degradation of the azo dye, providing the nanostructures with better photocatalytic activity.

Synthesis and Characterization of Nanoformulation of the Broad-Spectrum Enzyme Inhibitor Mancozeb by Polyethylene Glycol Capping and Its Dissipation Kinetics in Water Using TiO2 Nanoparticles

The poly(ethylene) glycol (PEG) capped mancozeb nanoformulation was prepared by the ultrasonic method using a 1% mancozeb solution and 20% capping agent, PEG-4000. The synthesized nanoformulation was characterized using UV-visible, FTIR, SEM and TEM techniques. The photolytic and photo catalytic experiments were carried out in a Borosil glass bottle in the presence of sunlight, varying the pH proportions at a single fortification level (1.0 g/mL) in ground water, under sunlight. The optimal catalyst concentration for complete degradation was observed to be 0.1 percent. The mancozeb nanoformulation in water was determined using the HPLC-PDA method, and the rate constant and the 50% degradation (DT50) values were calculated based on the results. The photolytic results show that there is no significant loss of residues due to adsorption. Titanium dioxide (TiO2) was discovered to be an excellent decontaminating catalyst in a variety of water samples. The compound survives for several days in the absence of a catalyst.

Plasmon-enhanced photothermal properties of Au@Ti3C2Tx nanosheets for antibacterial applications

Antibiotic-resistant bacterial strains have become an ever-increasing public concern due to their significant threats to health safety. Nanomaterial-based photothermal treatment has shown potential in antibacterial applications, but many nanomaterials exhibited limited photothermal activity that may compromise their antibacterial efficacies. Herein, we report a novel strategy based on efficient photothermal ablation and physical contact over a supported nanostructure by loading Au nanoparticles (NPs) on few-layered Ti₃C₂T_x nanosheets (NSs) for antibacterial treatment. Ti₃C₂T_x NSs are delaminated via etching and sonication, and act as a reductant for the in situ reduction of HAuCl₄·xH₂O, producing "naked" Au NPs without any stabilizers. Meanwhile, by adjusting the Au/Ti ratio, the size and loading of the Au NPs are finely regulated, thereby providing an ideal model of a surface-clean Au@Ti₃C₂T_x heterostructure for probing the composition-performance relationship. Upon irradiation with visible light, it exhibits synergistically enhanced photothermal conversion efficiency and stability, owing to the localized surface plasmonic resonance effect of Au NP and Au-NS interactions. Moreover, under visible light irradiation for 10 min, the Au@ Ti₃C₂T_x heterostructure exhibits excellent antibacterial activity for Gram-positive S. aureus and Gram-negative E. coli, and kills over 99% bacteria with a low dose of the nanomedicine suspension (50 μg mL^-1). The work demonstrates that the incorporation of transition metal carbides with plasmonic metal nanostructures is an effective strategy to enhance the photothermal antibacterial efficacy.

Effect of non-ionic surfactant in the solvothermal synthesis of anatase TiO2 nanoplates with a high percentage of exposed {001} facets and its role in the photocatalytic degradation of methylene blue dye

The synthesis of anatase TiO₂ nanoparticles with controlled morphology and increased {001} facets exposed without the presence of fluorine-derived substances is a challenge. Herein, we report a highly effective approach to fabricate anatase TiO₂ nanoplates with exposed {001} facets and their exploitation as robust photocatalytic materials for dye remediation. These materials were synthesized under controlled hydrolysis and condensation reactions, using titanium (IV) n-butoxide in an ethanolic solution, with acetic and sulfuric acids, by a solvothermal method at 190 °C with or without the presence of the non-ionic surfactant Triton® X-100 and then characterized. During TiO₂ crystal synthesis, the effect of a non-ionic surfactant on the TiO₂ particle growth was investigated. Our results demonstrate that the proposed method can synthesize pure and crystalline anatase TiO₂ square nanoplates that form nanostructured spheres with high surface area, uniformly sized mesopores, and exposed {001} facets. The presence of non-ionic surfactant increased the exposed {001} facets percentage of the formed nanoplates from 69 to 80%, decreased the crystallite thickness, but unaffected its crystalline phase and band gap energy. The kinetic constants (K_a e K_b) for the synthesized TiO₂ anatase nanoplates are considerably higher than the commercial TiO₂ anatase constant (K_c). The synthesized photocatalysts show higher efficiency in the photocatalytic removal of methylene blue (MB) than commercial TiO₂ (for t = 120 min).

Synthesis of ZnO/Au Nanocomposite for Antibacterial Applications

Annually, antimicrobial-resistant infections-related mortality worldwide accelerates due to the increased use of antibiotics during the coronavirus pandemic and the antimicrobial resistance, which grows exponentially, and disproportionately to the current rate of development of new antibiotics. Nanoparticles can be an alternative to the current therapeutic approach against multi-drug resistance microorganisms caused infections. The motivation behind this work was to find a superior antibacterial nanomaterial, which can be efficient, biocompatible, and stable in time. This study evaluated the antibacterial activity of ZnO-based nanomaterials with different morphologies, synthesized through the solvothermal method and further modified with Au nanoparticles through wet chemical reduction. The structure, crystallinity, and morphology of ZnO and ZnO/Au nanomaterials have been investigated with XRD, SEM, TEM, DLS, and FTIR spectroscopy. The antibacterial effect of unmodified ZnO and ZnO/Au nanomaterials against Escherichia coli and Staphylococcus aureus was investigated through disc diffusion and tetrazolium/formazan (TTC) assays. The results showed that the proposed nanomaterials exhibited significant antibacterial effects on the Gram-positive and Gram-negative bacteria. Furthermore, ZnO nanorods with diameters smaller than 50 nm showed better antibacterial activity than ZnO nanorods with larger dimensions. The antibacterial efficiency against Escherichia coli and Staphylococcus aureus improved considerably by adding 0.2% (w/w) Au to ZnO nanorods. The results indicated the new materials' potential for antibacterial applications.

Biosynthesis of TiO2 nanoparticles by Caricaceae (Papaya) shell extracts for antifungal application

Titanium dioxide nanoparticles (TiO₂ NPs) were prepared by Caricaceae (Papaya) Shell extracts. The Nanoparticles were analyzed by UV–Vis spectrums, X-ray diffractions, and energy-dispersive X-rays spectroscopy analyses with a scanning electron microscope. An antifungal study was carried out for TiO₂ NP in contradiction of S. sclerotiorums, R. necatrixs and Fusarium classes that verified a sophisticated inhibitions ratio for S. sclerotiorums (60.5%). Germs of pea were individually preserved with numerous concentrations of TiO₂ NPs. An experience of TiO₂ NPs (20%, 40%, 80% and 100%), as well as mechanisms that instigated momentous alterations in seed germinations, roots interval, shoot lengths, and antioxidant enzymes, were investigated. Associated with controls, the supreme seeds germinations, roots and plant growth were perceived with the treatments of TiO₂ NPs. Super-oxide dis-mutase and catalase activities increased because of TiO₂ NPs treatments. This advocates that TiO₂ Nanoparticles may considerably change antioxidant metabolisms in seed germinations.

Water Retention Behaviour and Fracture Toughness of Coir/Pineapple Leaf Fibre with Addition of Al2O3 Hybrid Composites under Ambient Conditions

Due to their high mechanical and physical properties, natural fibre-based composite materials have been important in many fields of application for four to five years. The chief intention of the current study is to determine the mechanical and water retention features of composite materials under ambient conditions. Coir and pineapple leaf fibre were used as a reinforcement, aluminium oxide as additives, and polyester as a matrix. The hybrid resources were laminated by the manual hand lay-up method. The mechanical characteristics like tensile, flexural, and fracture toughness properties were tested as per the ASTM standard. Nanoparticle weight ratio and its size variation significantly impact mechanical qualities. The hybrid composite’s water retention behaviour was tested for two types of water levels: ordinary tab water and nanofluid. The moisture uptake of the composites rose as the fibre volume increased, and after 640 hours, all of the composites had reached equilibrium. According to the results, the following combinations have the maximum mechanical strength: 15% wt.% coir, 15% wt.% pineapple, 10% wt.% nanofiller, and 60% wt.% polyester resin. The combinations mentioned above withstand the most load during the tests. Compared to 20% filler, 10% Al2O3 filler produces good interfacial adhesion in the current study. The fractured specimens were analyzed using scanning electron microscopic (SEM) pictures to recognize better the failure process of composites during mechanical testing.