Biological approach to synthesize TiO2 nanoparticles using Aeromonas hydrophila and its antibacterial activity

Investigate the biological activities of Lawsonia inermis extract synthesized from TiO2 doped graphene oxide nanoparticles

Nanoparticles of titanium dioxide (TiO2) were made by reacting graphene oxide (GO) with Lawsonia inermis leaf extract. X-ray diffraction (XRD) analysis revealed crystalline TiO2 doped GO nanoparticles composed of a variety of anatase phases. Initially, UV-vis spectroscopy was performed to confirm the biogenesis of TiO2 doped GO nanoparticles (NP's). Using SEM, the research showed that the biosynthesized TiO2 nanoparticles were mostly spherical, polydispersed, and of a nanoscale size. Because of the energy dispersive X-ray spectroscopy (EDS) pattern, distinct and robust peaks of titanium (Ti) and oxygen (O) were observed, which were supportive of the formation of TiO2 nanoparticles. By using fourier transform infrared (FTIR) spectroscopy, it was demonstrated that terpenoids, flavonoids, and proteins are involved in the biosynthesis and production of TiO2 doped GO nanoparticles. 2,2-diphenylpicrylhydrazyl (DPPH) assays were conducted to evaluate the free radical scavenging activity of TiO2 doped GO nanoparticles. Additionally, the TiO2 doped GO NPs had enhanced antioxidant activity when compared with the TiO2 matrix. A series of pure TiO2 and TiO2 doped GO nanoparticles (5, 10, 50, and 100 mg/mL) solutions were investigated for their antibacterial activities. In the current study, zebrafish embryos exposed to pure TiO2 and TiO2 doped GO nanoparticles were toxic and suffered a low survival rate based on concentration. During photocatalysis, O2˙ and ˙OH radicals are rapidly produced because of the reactive species trapping experiment. It was estimated that pure TiO2 nanoparticles and those doped with GO were 80% effective in degrading methyl orange(MO) after 120 min, respectively. RESEARCH HIGHLIGHTS: The UV-vis absorption spectra showed a maximum absorbance peak at 290 nm. SEM, the pure TiO2 doped GO NPs exhibit agglomeration and spherical shape. When tested in zebrafish embryos, TiO2 NPs are toxic at high concentrations. GO nanoparticles showed better antioxidant activity. NPs exhibited concentration dependent antioxidative activity.

Bacterial synthesis of metal nanoparticles as antimicrobials

Nanoscience, a pivotal field spanning multiple industries, including healthcare, focuses on nanomaterials characterized by their dimensions. These materials are synthesized through conventional chemical and physical methods, often involving costly and energy-intensive processes. Alternatively, biogenic synthesis using bacteria, fungi, or plant extracts offers a potentially sustainable and non-toxic approach for producing metal-based nanoparticles (NP). This eco-friendly synthesis approach not only reduces environmental impact but also enhances features of NP production due to the unique biochemistry of the biological systems. Recent advancements have shown that along with chemically synthesized NPs, biogenic NPs possess significant antimicrobial properties. The inherent biochemistry of bacteria enables the efficient conversion of metal salts into NPs through reduction processes, which are further stabilized by biomolecular capping layers that improve biocompatibility and functional properties. This mini review explores the use of bacteria to produce NPs with antimicrobial activities. Microbial technologies to produce NP antimicrobials have considerable potential to help address the antimicrobial resistance crisis, thus addressing critical health issues aligned with the United Nations Sustainability Goal #3 of good health and well-being.

Synthesis of Silver Nanoparticles from Aeromonas caviae for Antibacterial Activity and In Vivo Effects in Rats

Silver nanoparticles (AgNPs) have excellent antimicrobial properties, as they can inhibit multidrug-resistant (MDR) pathogens. Furthermore, bio-AgNPs have potential applications in medicine due to their low toxicity and high stability. Here, AgNPs were synthesized from the biomass of Aeromonas caviae isolated from a sediment sample and subsequently characterized. The UV-Vis spectra of AgNPs in aqueous medium peaked at 417 nm, matching their plasmon absorption. The X-ray diffraction analysis (XRD) pattern of AgNPs showed four peaks at 2θ values, corresponding to Ag diffraction faces. Absorption band peaks at 3420.16, 1635.54, and 1399.43 cm-1 were identified by Fourier-transform infrared spectroscopy (FTIR) analysis as belonging to functional groups of AgNP-associated biomolecules. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that the nanoparticles are spherical and pseudospherical, with sizes of 15-25 nm. Agar well diffusion minimal inhibitory concentration (MIC) assays were used to assess the antibacterial activity of the nanoparticles against MDR pathogens. AgNPs exhibited antibacterial activity against MDR bacteria. Two groups of albino rats received intraperitoneal injections of AgNPs at 15 mg/kg or 30 mg/kg for 7 days. Blood, kidney, and liver samples were collected to investigate hematological, biochemical, and histopathological alterations. Administered AgNPs in rats fluctuated in liver and kidney function parameters. The ultrastructural impacts of AgNPs were more prominent at higher doses. The results proved the easy, fast, and efficient synthesis of AgNPs using A. caviae isolates and demonstrated the remarkable potential of these AgNPs as antibacterial agents. Nanotoxicological studies are required to identify the specific dose that balances optimal antibacterial activity with minimal toxicity to human health.

PDADMAC/Alginate-Coated Gold Nanorod For Eradication of Staphylococcus Aureus Biofilms

Introduction

Over 75% of clinical microbiological infections are caused by bacterial biofilms that grow on wounds or implantable medical devices. This work describes the development of a new poly(diallyldimethylammonium chloride) (PDADMAC)/alginate-coated gold nanorod (GNR/Alg/PDADMAC) that effectively disintegrates the biofilms of Staphylococcus aureus (S. aureus), a prominent pathogen responsible for hospital-acquired infections.

Methods

GNR was synthesised via seed-mediated growth method, and the resulting nanoparticles were coated first with Alg and then PDADMAC. FTIR, zeta potential, transmission electron microscopy, and UV-Vis spectrophotometry analysis were performed to characterise the nanoparticles. The efficacy and speed of the non-coated GNR and GNR/Alg/PDADMAC in disintegrating S. aureus-preformed biofilms, as well as their in vitro biocompatibility (L929 murine fibroblast) were then studied.

Results

The synthesised GNR/Alg/PDADMAC (mean length: 55.71 ± 1.15 nm, mean width: 23.70 ± 1.13 nm, aspect ratio: 2.35) was biocompatible and potent in eradicating preformed biofilms of methicillin-resistant (MRSA) and methicillin-susceptible S. aureus (MSSA) when compared to triclosan, an antiseptic used for disinfecting S. aureus colonisation on abiotic surfaces in the hospital. The minimum biofilm eradication concentrations of GNR/Alg/PDADMAC (MBEC50 for MRSA biofilm = 0.029 nM; MBEC50 for MSSA biofilm = 0.032 nM) were significantly lower than those of triclosan (MBEC50 for MRSA biofilm = 10,784 nM; MBEC50 for MRSA biofilm 5967 nM). Moreover, GNR/Alg/PDADMAC was effective in eradicating 50% of MRSA and MSSA biofilms within 17 min when used at a low concentration (0.15 nM), similar to triclosan at a much higher concentration (50 µM). Disintegration of MRSA and MSSA biofilms was confirmed by field emission scanning electron microscopy and confocal laser scanning microscopy.

Conclusion

These findings support the potential application of GNR/Alg/PDADMAC as an alternative agent to conventional antiseptics and antibiotics for the eradication of medically important MRSA and MSSA biofilms.

Synthesis and characterization of titanium dioxide nanoparticles from Bacillus subtilis MTCC 8322 and its application for the removal of methylene blue and orange G dyes under UV light and visible light

Over the last decade there has been a huge increase in the green synthesis of nanoparticles. Moreover, there is a continuous increase in harnessing the potential of microorganisms for the development of efficient and biocompatible nanoparticles around the globe. In the present research work, investigators have synthesized TiO2 NPs by harnessing the potential of Bacillus subtilis MTCC 8322 (Gram-positive) bacteria. The formation and confirmation of the TiO2 NPs synthesized by bacteria were carried out by using UV-Vis spectroscopy, Fourier transforms infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDX/EDS). The size of the synthesized TiO2 NPs was 80-120 nm which was spherical to irregular in shape as revealed by SEM. FTIR showed the characteristic bands of Ti-O in the range of 400-550 cm-1 and 924 cm-1 while the band at 2930 cm-1 confirmed the association of bacterial biomolecules with the synthesized TiO2 NPs. XRD showed two major peaks; 27.5° (rutile phase) and 45.6° (anatase phase) for the synthesized TiO2 NPs. Finally, the potential of the synthesized TiO2 NPs was assessed as an antibacterial agent and photocatalyst. The remediation of Methylene blue (MB) and Orange G (OG) dyes was carried out under UV- light and visible light for a contact time of 150-240 min respectively. The removal efficiency for 100 ppm MB dye was 25.75% and for OG dye was 72.24% under UV light, while in visible light, the maximum removal percentage for MB and OG dye was 98.85% and 80.43% respectively at 90 min. Moreover, a kinetic study and adsorption isotherm study were carried out for the removal of both dyes, where the pseudo-first-order for MB dye is 263.269 and 475554.176 mg/g for OG dye. The pseudo-second-order kinetics for MB and OG dye were 188.679 and 1666.667 mg/g respectively. In addition to this, the antibacterial activity of TiO2 NPs was assessed against Bacillus subtilis MTCC 8322 (Gram-positive) and Escherichia coli MTCC 8933 (Gram-negative) where the maximum zone of inhibition in Bacillus subtilis MTCC 8322 was about 12 mm, and for E. coli 16 mm.

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.

An Overview of Metallic Nanoparticles: Classification, Synthesis, Applications, and their Patents

BACKGROUND

Nanotechnology has gained enormous attention in pharmaceutical research. Nanotechnology is used in the development of nanoparticles with sizes ranging from 1-100 nm, with several extraordinary features. Metallic nanoparticles (MNPs) are used in various areas, such as molecular biology, biosensors, bio imaging, biomedical devices, diagnosis, pharmaceuticals, etc., for their specific applications.

METHODOLOGY

For this study, we have performed a systematic search and screening of the literature and identified the articles and patents focusing on various physical, chemical, and biological methods for the synthesis of metal nanoparticles and their pharmaceutical applications.

RESULTS

A total of 174 references have been included in this present review, of which 23 references for recent patents were included. Then, 29 papers were shortlisted to describe the advantages, disadvantages, and physical and chemical methods for their synthesis, and 28 articles were selected to provide the data for biological methods for the formulation of metal NPs from bacteria, algae, fungi, and plants with their extensive synthetic procedures. Moreover, 27 articles outlined various clinical applications of metal NPs due to their antimicrobial and anticancer activities and their use in drug delivery.

CONCLUSION

Several reviews are available on the synthesis of metal nanoparticles and their pharmaceutical applications. However, this review provides updated research data along with the various methods employed for their development. It also summarizes their various advantages and clinical applications (anticancer, antimicrobial drug delivery, and many others) for various phytoconstituents. The overview of earlier patents by several scientists in the arena of metallic nanoparticle preparation and formulation is also presented. This review will be helpful in increasing the current knowledge and will also inspire to innovation of nanoparticles for the precise and targeted delivery of phytoconstituents for the treatment of several diseases.

Understanding the effective breakdown of PAH s in water through the use of g-C3N4-Ag-Cu-Ni nanocomposites

The research work aimed to explore the suitability of using a novel g- C3N4-Ag-Cu-Ni nanocomposite for the simultaneous degradation of pyrene in wastewater. The outcome revealed that the g- C3N4 phase was successfully fabricated on the g-C3N4-based compound, and the existence of the g- C3N4-based compound beneficially stabilized the Ag-Cu-Ni particles. The g- C3N4-Ag-Cu-Ni nanocomposite demonstrated excellent performance in pyrene degradation under various conditions. The degradation of pyrene increased with a rise in the dosage of g- C3N4-Ag-Cu-Ni. These findings indicate that the g- C3N4-Ag-Cu-Ni nanocomposite could be a promising material for water purification, especially for the simultaneous photocatalytic and antimicrobial treatment of contaminated water bodies. The study provides a helpful guide for future research in this field.

Antiultraviolet, Antioxidant, and Antimicrobial Properties and Anticancer Potential of Novel Environmentally Friendly Amide-Modified Gallic Acid Derivatives

Polyphenols and amides isolated from natural products have various biological functions, such as antioxidant, antimicrobial, anticancer, and antiviral activities, and they are widely used in the fields of food and medicine. In this work, four novel and environmentally friendly amide-modified gallic acid derivatives (AMGADs), which were prepared by using different amides to modify gallic acid (GA) from Polygonaceae plants, displayed good antiultraviolet (anti-UV), antioxidant, antimicrobial, and anticancer effects. Significantly, the anti-UV capability of compounds n1 and n2 was notably superior to that of the UV absorber GA. Moreover, compound n2 possessed better 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) scavenging ability and ferric reducing antioxidant power than vitamin C. The antibacterial activities of all AMGADs, with inhibition rates of more than 96.00 and 79.00% for Escherichia coli and Staphylococcus aureus, respectively, were better than those of GA. Compound n1 had broad-spectrum anticancer activity, and its inhibitory effect on HepG2 cells exceeded that of 5-fluorouracil. The good and rich bioactivities of these AMGADs revealed that combining GA with amides is conducive to improving the activity of GA, and this study laid a good foundation for their scientific application in the fields of food and medicine.

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.

Antimicrobial properties of green synthesized novel TiO2 nanoparticles using Iranian propolis extracts

The oral antimicrobial and cytotoxic properties of green synthesized novel titanium dioxide nanoparticles (TiO2 NPs) using Iranian propolis extracts were investigated on oral bacteria and fibroblast cells. In this study, propolis was sampled, and alcoholic extracts were prepared. The TiO2 NPs were biosynthesized using propolis extracts. The synthesized TiO2 NPs were characterized by scanning electron microscope (SEM), X-ray diffraction analysis, energy-dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering, ultraviolet-visible (UV-Vis), transmission electron microscope, Brunauer-Emmett-Teller, and zeta potential. MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide), minimal inhibitory concentration, minimum bactericidal concentration, minimum fungicidal concentration, biofilm formation, and degradation tests were studied to clarify the oral antimicrobial properties of green synthesized TiO2  NPs. According to the FTIR analysis, the propolis extract contained flavonoids and phenolic compounds in addition to TiO2 NPs. Additionally, UV-Vis revealed that intense bands had formed NPs. EDX spectra and SEM images revealed that the stabilizing agent was in perfect quasi-spherical shapes around 21 nm. An EDX spectrum was used to verify the presence of titanium and oxygen. There were no significant cytotoxicity effects. The antibacterial results showed that Pro1TiO2 (Khalkhal sample) had better effects than Pro2TiO2 (Gilan sample) and TiO2 NPs. The present study presents a new process for synthesizing TiO2 NPs from propolis extracts with less toxic effects and user-friendly, eco-friendly, and economical materials. Pro1TiO2 NPs may be considered the best candidate for clinical application.

Biosynthesis of Copper Oxide and Silver Nanoparticles by Bacillus Spores and Evaluation of the Feasibility of Their Use in Antimicrobial Paints

Modification of paint with nanoparticles (NPs) provides self-cleaning, water/dirt-repellent, and other properties. Therefore, the aim of the present study was to biosynthesize silver (Ag) and copper oxide (CuO) NPs and to prepare NP-modified paint. To this end, AgNPs and CuONPs were biosynthesized using Bacillus atrophaeus spores and commercial and crude dipicolinic acid (DPA) extracted from the spore of this bacterium. The synthesized NPs were characterized using electron microscopy, Fourier-transform infrared (FTIR), X-ray diffraction analysis (XRD), and energy-dispersive X-ray spectroscopy (EDS) methods. A minimum inhibitory concentration (MIC) assay of NPs against Escherichia coli ATCC8739 and Staphylococcus aureus ATCC6538 was carried out. The antibacterial effects of prepared NP-paint complexes were assessed using an optical density (OD) comparison before and after adding metal sheets coated with NP-paint complexes into the nutrient broth medium. Four different types of NPs were synthesized in this research: AgNPs synthesized by spore (A), AgNPs synthesized by commercial DPA (B), AgNPs synthesized by crude DPA (C), and CuONPs synthesized by spore (D). SEM analysis confirmed the spherical shape of NPs. According to the results, NPs A, B, and D showed higher antibacterial activity against S. aureus compared to E. coli. Furthermore, the analysis of the antibacterial effects of NP-paint complexes suggested that paint-NPs A, B, and C displayed higher activity on E. coli compared to S. aureus. Moreover, the antibacterial effect of paint-NP D was significantly lower than other NPs. According to this robust antibacterial effect on pathogenic bacteria, it seems that these NP-paint complexes could be useful in public places such as hospitals, airports, dormitories, schools, and office buildings, where the rate of transmission of infection is high.

A review on the green synthesis of nanoparticles, their biological applications, and photocatalytic efficiency against environmental toxins

Green synthesis of nanoparticles (NPs) using plant materials and microorganisms has evolved as a sustainable alternative to conventional techniques that rely on toxic chemicals. Recently, green-synthesized eco-friendly NPs have attracted interest for their potential use in various biological applications. Several studies have demonstrated that green-synthesized NPs are beneficial in multiple medicinal applications, including cancer treatment, targeted drug delivery, and wound healing. Additionally, due to their photodegradation activity, green-synthesized NPs are a promising tool in environmental remediation. Photodegradation is a process that uses light and a photocatalyst to turn a pollutant into a harmless product. Green NPs have been found efficient in degrading pollutants such as dyes, herbicides, and heavy metals. The use of microbes and flora in green synthesis technology for nanoparticle synthesis is biologically safe, cost-effective, and eco-friendly. Plants and microbes can now use and accumulate inorganic metallic ions in the environment. Various NPs have been synthesized via the bio-reduction of biological entities or their extracts. There are several biological and environmental uses for biologically synthesized metallic NPs, such as photocatalysis, adsorption, and water purification. Since the last decade, the green synthesis of NPs has gained significant interest in the scientific community. Therefore, there is a need for a review that serves as a one-stop resource that points to relevant and recent studies on the green synthesis of NPs and their biological and photocatalytic efficiency. This review focuses on the green fabrication of NPs utilizing diverse biological systems and their applications in biological and photodegradation processes.

Recent Advances and Perspectives of Nanomaterials in Agricultural Management and Associated Environmental Risk: A Review

The advancement in nanotechnology has enabled a significant expansion in agricultural production. Agri-nanotechnology is an emerging discipline where nanotechnological methods provide diverse nanomaterials (NMs) such as nanopesticides, nanoherbicides, nanofertilizers and different nanoforms of agrochemicals for agricultural management. Applications of nanofabricated products can potentially improve the shelf life, stability, bioavailability, safety and environmental sustainability of active ingredients for sustained release. Nanoscale modification of bulk or surface properties bears tremendous potential for effective enhancement of agricultural productivity. As NMs improve the tolerance mechanisms of the plants under stressful conditions, they are considered as effective and promising tools to overcome the constraints in sustainable agricultural production. For their exceptional qualities and usages, nano-enabled products are developed and enforced, along with agriculture, in diverse sectors. The rampant usage of NMs increases their release into the environment. Once incorporated into the environment, NMs may threaten the stability and function of biological systems. Nanotechnology is a newly emerging technology, so the evaluation of the associated environmental risk is pivotal. This review emphasizes the current approach to NMs synthesis, their application in agriculture, interaction with plant-soil microbes and environmental challenges to address future applications in maintaining a sustainable environment.

Biosynthesis, characterization and optimization of TiO2 nanoparticles by novel marine halophilic Halomonas sp. RAM2: application of natural dye-sensitized solar cells

BACKGROUND

Metal oxide nanoparticles (NPs) are becoming valuable due to their novel applications. The green synthesis of TiO₂ NPs is more popular as a flexible and eco-friendly method compared to traditional chemical synthesis methods. TiO₂ NPs are the most commonly used semiconductor in dye-sensitized solar cells (DSSCs).

RESULTS

The biogenic TiO₂ NPs were produced extracellularly by the marine halophilic bacterium Halomonas sp. RAM2. Response surface methodology (RSM) was used to optimize the biosynthesis process, resulting in a starting TiO₂ concentration of 0.031 M and a pH of 5 for 92 min (⁓15 nm). TiO₂ NPs were well-characterized after the calcination process at different temperatures of 500, 600, 700 and 800 °C. Anatase TiO₂ NPs (calcined at 500 °C) with a smaller surface area and a wider bandgap were nominated for use in natural dye-sensitized solar cells (NDSSCs). The natural dye used as a photosensitizer is a mixture of three carotenoids extracted from the marine bacterium Kocuria sp. RAM1. NDSSCs were evaluated under standard illumination. After optimization of the counter electrode, NDSSC_Bio(10) (10 layers) demonstrated the highest photoelectric conversion efficiency (η) of 0.44%, which was almost as good as NDSSC_P25 (0.55%).

CONCLUSION

The obtained results confirmed the successful green synthesis of TiO₂ NPs and suggested a novel use in combination with bacterial carotenoids in DSSC fabrication, which represents an initial step for further efficiency enhancement studies.

Recent Advances in the Investigation of Poly(lactic acid) (PLA) Nanocomposites: Incorporation of Various Nanofillers and their Properties and Applications

Poly(lactic acid) (PLA) is considered the most promising biobased substitute for fossil-derived polymers due to its compostability, biocompatibility, renewability, and good thermomechanical properties. However, PLA suffers from several shortcomings, such as low heat distortion temperature, thermal resistance, and rate of crystallization, whereas some other specific properties, i.e., flame retardancy, anti-UV, antibacterial or barrier properties, antistatic to conductive electrical characteristics, etc., are required by different end-use sectors. The addition of different nanofillers represents an attractive way to develop and enhance the properties of neat PLA. Numerous nanofillers with different architectures and properties have been investigated, with satisfactory achievements, in the design of PLA nanocomposites. This review paper overviews the current advances in the synthetic routes of PLA nanocomposites, the imparted properties of each nano-additive, as well as the numerous applications of PLA nanocomposites in various industrial fields.

Bioinorganic Nanoparticles for the Remediation of Environmental Pollution: Critical Appraisal and Potential Avenues

Nowadays, environmental pollution has become a critical issue for both developed and developing countries. Because of excessive industrialization, burning of fossil fuels, mining and exploration, extensive agricultural activities, and plastics, the environment is being contaminated rapidly through soil, air, and water. There are a variety of approaches for treating environmental toxins, but each has its own set of restrictions. As a result, various therapies are accessible, and approaches that are effective, long-lasting, less harmful, and have a superior outcome are extensively demanded. Modern research advances focus more on polymer-based nanoparticles, which are frequently used in drug design, drug delivery systems, environmental remediation, power storage, transformations, and other fields. Bioinorganic nanomaterials could be a better candidate to control contaminants in the environment. In this article, we focused on their synthesis, characterization, photocatalytic process, and contributions to environmental remediation against numerous ecological hazards. In this review article, we also tried to explore their recent advancements and futuristic contributions to control and prevent various pollutants in the environment.

Antiglycation potential of plant based TiO2 nanoparticle in D-ribose glycated BSA in vitro

Biosynthetic procedure is one of the best alternatives, inexpensive and ecologically sound for the synthesis of titanium dioxide (TiO₂ ) nanoparticles using a methanolic extract of medicinal plant. The main prospect of this study was to investigate the antiglycation activity of the TiO₂ nanoparticles (TNP) prepared by ethanolic leaf extract of the Coleus scutellarioides. In this study, biosynthesized TNP characterized with UV-Visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscope. These TNP were further investigated with respect to their antiglycation property and it was checked in the mixture of d-ribose glycated bovine serum albumin (BSA) by measuring ketoamine, carbonyl content, Advanced glycation end products (AGEs) and aggregation of protein instigated by glycation process. The inhibitory effect of TNP to restore the structure of BSA in presence of d-ribose were also characterize by biophysical techniques mentioned above. Therefore, the findings of this study suggest repurposing of TNP for its antiglycation property that could be helpful in prevention of glycation instigated AGEs formation and structural loss of proteins.

Green Synthesis of Metal Oxides Semiconductors for Gas Sensing Applications

During recent decades, metal oxide semiconductors (MOS) have sparked more attention in various applications and industries due to their excellent sensing characteristics, thermal stability, abundance, and ease of synthesis. They are reliable and accurate for measuring and monitoring environmentally important toxic gases, such as NO₂, NO, N₂O, H₂S, CO, NH₃, CH₄, SO₂, and CO₂. Compared to other sensing technologies, MOS sensors are lightweight, relatively inexpensive, robust, and have high material sensitivity with fast response times. Green nanotechnology is a developing branch of nanotechnology and aims to decrease the negative effects of the production and application of nanomaterials. For this purpose, organic solvents and chemical reagents are not used to prepare metal nanoparticles. On the contrary, the synthesis of metal or metal oxide nanoparticles is done by microorganisms, either from plant extracts or fungi, yeast, algae, and bacteria. Thus, this review aims at illustrating the possible green synthesis of different metal oxides such as ZnO, TiO₂, CeO₂, SnO₂, In₂O₃, CuO, NiO, WO_3, and Fe₃O₄, as well as metallic nanoparticles doping.

Effect of Pd-Sensitization on Poisonous Chlorine Gas Detection Ability of TiO2: Green Synthesis and Low-Temperature Operation

Ganoderma lucidum mushroom-mediated green synthesis of nanocrystalline titanium dioxide (TiO₂) is explored via a low-temperature (≤70 °C) wet chemical method. The role of Ganoderma lucidum mushroom extract in the reaction is to release the ganoderic acid molecules that tend to bind to the Ti⁴⁺ metal ions to form a titanium-ganoderic acid intermediate complex for obtaining TiO₂ nanocrystallites (NCs), which is quite novel, considering the recent advances in fabricated gas sensing materials. The X-ray powder diffraction, field emission scanning electron microscopy, Raman spectroscopy, and Brunauer–Emmett–Teller measurements etc., are used to characterize the crystal structure, surface morphology, and surface area of as-synthesized TiO₂ and Pd-TiO₂ sensors, respectively. The chlorine (Cl₂) gas sensing properties are investigated from a lower range of 5 ppm to a higher range of 400 ppm. In addition to excellent response–recovery time, good selectivity, constant repeatability, as well as chemical stability, the gas sensor efficiency of the as-synthesized Pd-TiO₂ NC sensor is better (136% response at 150 °C operating temperature) than the TiO₂ NC sensor (57% at 250 °C operating temperature) measured at 100 ppm (Cl₂) gas concentration, suggesting that the green synthesized Pd-TiO₂ sensor demonstrates efficient Cl₂ gas sensing properties at low operating temperatures over pristine ones.

Phyto Synthesis of Manganese-Doped Zinc Nanoparticles Using Carica papaya Leaves: Structural Properties and Its Evaluation for Catalytic, Antibacterial and Antioxidant Activities

The current study aims to synthesize bimetal oxide nanoparticles (zinc and manganese ions) using the carica papaya leaf extract. The crystallite size of the nanoparticle from X-ray diffraction method was found to be 19.23 nm. The nanosheet morphology was established from Scanning Electron Microscopy. Energy-dispersive X-ray diffraction was used to determine the elemental content of the synthesized material. The atomic percentage of Mn and Zn was found to be 15.13 and 26.63. The weight percentage of Mn and Zn was found to be 7.08 and 10.40. From dynamic light scattering analysis, the hydrodynamic diameter and zeta potential was found to be 135.1 nm and −33.36 eV. The 1,1-diphenyl-2-picryl hydroxyl radical, hydroxyl radical, FRAP, and hydrogen peroxide scavenging tests were used to investigate the antioxidant activity of Mn-Zn NPs. Mn-Zn NPs have substantial antioxidant properties. The photocatalytic activity of the Mn-Zn NPs was assessed by their ability to degrade Erichrome black T (87.67%), methyl red dye (78.54%), and methyl orange dye (69.79%). Additionally, it had significant antimicrobial action S. typhi showed a higher zone of inhibition 14.3 ± 0.64 mm. Mn-Zn nanoparticles were utilized as a catalyst for p-nitrophenol reduction. The bimetal oxide Mn-Zn NPs synthesized using C. papaya leaf extract exhibited promising dye degradation activity in wastewater treatment. Thus, the aforementioned approach will be a novel, low cost and ecofriendly approach.

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

Nanotechnology is a fast-expanding area with a wide range of applications in science, engineering, health, pharmacy, and other fields. Nanoparticles (NPs) are frequently prepared via a variety of physical and chemical processes. Simpler, sustainable, and cost-effective green synthesis technologies have recently been developed. The synthesis of titanium dioxide nanoparticles (TiO₂ NPs) in a green/sustainable manner has gotten a lot of interest in the previous quarter. Bioactive components present in organisms such as plants and bacteria facilitate the bio-reduction and capping processes. The biogenic synthesis of TiO₂ NPs, as well as the different synthesis methods and mechanistic perspectives, are discussed in this review. A range of natural reducing agents including proteins, enzymes, phytochemicals, and others, are involved in the synthesis of TiO₂ NPs. The physics of antibacterial and photocatalysis applications were also thoroughly discussed. Finally, we provide an overview of current research and future concerns in biologically mediated TiO₂ nanostructures-based feasible platforms for industrial applications.

Recent Advancements in Plant-Derived Nanomaterials Research for Biomedical Applications

Engineering, physics, chemistry, and biology are all involved in nanotechnology, which comprises a wide variety of multidisciplinary scientific field devices. The holistic utilization of metallic nanoparticles in the disciplines of bio-engineering and bio-medicine has attracted a great deal of attention. Medical nanotechnology research can offer immense health benefits for humans. While the advantages of developing nanomaterials have been well documented, it is precisely apparent that there are still some major issues that remain unattended to those need to be resolved immediately so as to ensure that they do not adversely affect living organisms in any manner. The existence of nanoparticles gives them particular value in biology and materials science, as an emerging scientific field, with multiple applications in science and technology, especially with numerous frontiers in the development of new materials. Presented here is a review of recent noteworthy developments regarding plant-derived nanomaterials and their use in the development of medicine and biomedical applications around the world.

Green Approach Towards Morphology-Controlled Synthesis of Zein-Functionalized TiO2 Nanoparticles for Cosmeceutical Application

Biomolecular approaches for synthesis of inorganic nanoparticle are very popular among researchers and exhibit significant shape-directing morphologies in classified condition. The proteins are the most abundant macromolecules and employed for the hybrid synthesis as well as shape-directing agent. The present study is designed to investigate the potential role of a plant protein 'zein' to synthesize hybrid TiO₂ nanoparticles. This versatile amphiphilic protein paves a unique path towards shape directing synthesis and act as template in the biomineralization process. The structural changes occurred in protein structure is thoroughly characterized using the circular dichroism (CD) and FTIR spectroscopy. UV, XPS and HRTEM analysis confirms the presence of zein on the nanoparticle surface. The proposed approach provides finely engineered nano-cuboidal (22.75±5.07 nm) geometry with homogenous dispersion, curved edged cuboids (403.51±0.05 nm) and spherical (97.85±0.62 nm) shaped from different modification, as evidenced by TEM. We also discussed in-vitro method for the detection of antimicrobial activity of nanocuboids against acne causing microorganisms such as Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Streptococcus agalactiae. Our results demonstrate that hybrid nanocuboids could be an efficient green material and provide cognitive antimicrobial evidence that could be deployed for cosmeceutical application.

Green Synthesis of Metal and Metal Oxide Nanoparticles Using Different Plants’ Parts for Antimicrobial Activity and Anticancer Activity: A Review Article

Nanotechnology emerged as a scientific innovation in the 21st century. Metallic nanoparticles (metal or metal oxide nanoparticles) have attained remarkable popularity due to their interesting biological, physical, chemical, magnetic, and optical properties. Metal-based nanoparticles can be prepared by utilizing different biological, physical, and chemical methods. The biological method is preferred as it provides a green, simple, facile, ecofriendly, rapid, and cost-effective route for the green synthesis of nanoparticles. Plants have complex phytochemical constituents such as carbohydrates, amino acids, phenolics, flavonoids, terpenoids, and proteins, which can behave as reducing and stabilizing agents. However, the mechanism of green synthesis by using plants is still highly debatable. In this report, we summarized basic principles or mechanisms of green synthesis especially for metal or metal oxide (i.e., ZnO, Au, Ag, and TiO2, Fe, Fe2O3, Cu, CuO, Co) nanoparticles. Finally, we explored the medical applications of plant-based nanoparticles in terms of antibacterial, antifungal, and anticancer activity.

Phyto-fabricated Nanoparticles and Their Anti-biofilm Activity: Progress and Current Status

Biofilm is the self-synthesized, mucus-like extracellular polymeric matrix that acts as a key virulence factor in various pathogenic microorganisms, thereby posing a serious threat to human health. It has been estimated that around 80% of hospital-acquired infections are associated with biofilms which are found to be present on both biotic and abiotic surfaces. Antibiotics, the current mainstream treatment strategy for biofilms are often found to be futile in the eradication of these complex structures, and to date, there is no effective therapeutic strategy established against biofilm infections. In this regard, nanotechnology can provide a potential platform for the alleviation of this problem owing to its unique size-dependent properties. Accordingly, various novel strategies are being developed for the synthesis of different types of nanoparticles. Bio-nanotechnology is a division of nanotechnology which is gaining significant attention due to its ability to synthesize nanoparticles of various compositions and sizes using biotic sources. It utilizes the rich biodiversity of various biological components which are biocompatible for the synthesis of nanoparticles. Additionally, the biogenic nanoparticles are eco-friendly, cost-effective, and relatively less toxic when compared to chemically or physically synthesized alternatives. Biogenic synthesis of nanoparticles is a bottom-top methodology in which the nanoparticles are formed due to the presence of biological components (plant extract and microbial enzymes) which act as stabilizing and reducing agents. These biosynthesized nanoparticles exhibit anti-biofilm activity via various mechanisms such as ROS production, inhibiting quorum sensing, inhibiting EPS production, etc. This review will provide an insight into the application of various biogenic sources for nanoparticle synthesis. Furthermore, we have highlighted the potential of phytosynthesized nanoparticles as a promising antibiofilm agent as well as elucidated their antibacterial and antibiofilm mechanism.

Novel Synthesis of Titanium Oxide Nanoparticles: Biological Activity and Acute Toxicity Study

Titanium oxide nanoparticles (TiO₂ NPs) have been attracting numerous research studies due to their activity; however, there is a growing concern about the corresponding toxicity. Here in the present study, titanium oxide nanoparticles were newly synthesized using propolis extract followed by antimicrobial activity, cytotoxicity assay using human cancer cell lines, and acute toxicity study. The physicochemical characterization of the newly synthesized TiO₂ NPs had average size = 57.5 nm, PdI = 0.308, and zeta potential = −32.4 mV. Antimicrobial activity assessment proved the superior activity against Gram-positive compared to Gram-negative bacteria and yeast (lowest MIC values 8, 32, and 32, respectively). The newly synthesized TiO₂ NPs showed a potent activity against the following human cancer cell lines: liver (HepG-2) (IC50 8.5 µg/mL), colon (Caco-2), and breast (MDA-MB 231) (IC50 11.0 and 18.7 µg/mL). In vivo acute toxicity study was conducted using low (10 mg/kg) and high (1000 mg/kg) doses of the synthesized TiO₂ NPs in albino male rats. Biochemistry and histopathology of the liver, kidney, and brain proved the safety of the synthesized TiO₂ NPs at low dose while at high dose, there was TiO₂ NPs deposit in different vital organs except the cerebral tissue.

Green Synthesized Metal Oxide Nanoparticles Mediate Growth Regulation and Physiology of Crop Plants under Drought Stress

Metal oxide nanoparticles (MONPs) are regarded as critical tools for overcoming ongoing and prospective crop productivity challenges. MONPs with distinct physiochemical characteristics boost crop production and resistance to abiotic stresses such as drought. They have recently been used to improve plant growth, physiology, and yield of a variety of crops grown in drought-stressed settings. Additionally, they mitigate drought-induced reactive oxygen species (ROS) through the aggregation of osmolytes, which results in enhanced osmotic adaptation and crop water balance. These roles of MONPs are based on their physicochemical and biological features, foliar application method, and the applied MONPs concentrations. In this review, we focused on three important metal oxide nanoparticles that are widely used in agriculture: titanium dioxide (TiO2), zinc oxide (ZnO), and iron oxide (Fe3O4). The impacts of various MONPs forms, features, and dosages on plant growth and development under drought stress are summarized and discussed. Overall, this review will contribute to our present understanding of MONPs' effects on plants in alleviating drought stress in crop plants.

Endophytic Nanotechnology: An Approach to Study Scope and Potential Applications

Nanotechnology has become a very advanced and popular form of technology with huge potentials. Nanotechnology has been very well explored in the fields of electronics, automobiles, construction, medicine, and cosmetics, but the exploration of nanotecnology's use in agriculture is still limited. Due to climate change, each year around 40% of crops face abiotic and biotic stress; with the global demand for food increasing, nanotechnology is seen as the best method to mitigate challenges in disease management in crops by reducing the use of chemical inputs such as herbicides, pesticides, and fungicides. The use of these toxic chemicals is potentially harmful to humans and the environment. Therefore, using NPs as fungicides/ bactericides or as nanofertilizers, due to their small size and high surface area with high reactivity, reduces the problems in plant disease management. There are several methods that have been used to synthesize NPs, such as physical and chemical methods. Specially, we need ecofriendly and nontoxic methods for the synthesis of NPs. Some biological organisms like plants, algae, yeast, bacteria, actinomycetes, and fungi have emerged as superlative candidates for the biological synthesis of NPs (also considered as green synthesis). Among these biological methods, endophytic microorganisms have been widely used to synthesize NPs with low metallic ions, which opens a new possibility on the edge of biological nanotechnology. In this review, we will have discussed the different methods of synthesis of NPs, such as top-down, bottom-up, and green synthesis (specially including endophytic microorganisms) methods, their mechanisms, different forms of NPs, such as magnesium oxide nanoparticles (MgO-NPs), copper nanoparticles (Cu-NPs), chitosan nanoparticles (CS-NPs), β-d-glucan nanoparticles (GNPs), and engineered nanoparticles (quantum dots, metalloids, nonmetals, carbon nanomaterials, dendrimers, and liposomes), and their molecular approaches in various aspects. At the molecular level, nanoparticles, such as mesoporous silica nanoparticles (MSN) and RNA-interference molecules, can also be used as molecular tools to carry genetic material during genetic engineering of plants. In plant disease management, NPs can be used as biosensors to diagnose the disease.

Synthesis, Characterization, Applications, and Toxicity of Green Synthesized Nanoparticles

Nanotechnology is a cutting-edge area with numerous industrial applications. Nanoparticles are structures that have dimensions ranging from 1-100 nm which exhibit significantly different mechanical, optical, electrical, and chemical properties when compared with their larger counterparts. Synthetic routes that use natural sources, such as plant extracts, honey, and microorganisms are environmentally friendly and low-cost methods that can be used to obtain nanoparticles. These methods of synthesis generate products that are more stable and less toxic than those obtained using conventional methods. Nanoparticles formed by titanium dioxide, zinc oxide, silver, gold, and copper, as well as cellulose nanocrystals are among the nanostructures obtained by green synthesis that have shown interesting applications in several technological industries. Several analytical techniques have also been used to analyze the size, morphology, hydrodynamics, diameter, and chemical functional groups involved in the stabilization of the nanoparticles as well as to quantify and evaluate their formation. Despite their pharmaceutical, biotechnological, cosmetic, and food applications, studies have detected their harmful effects on human health and the environment; and thus, caution must be taken in uses involving living organisms. The present review aims to present an overview of the applications, the structural properties, and the green synthesis methods that are used to obtain nanoparticles, and special attention is given to those obtained from metal ions. The review also presents the analytical methods used to analyze, quantify, and characterize these nanostructures.

Use of Different Natural Products to Control Growth of Titanium Oxide Nanoparticles in Green Solvent Emulsion, Characterization, and Their Photocatalytic Application

Water, one of the crucial and the pillar resources to every living thing, could be polluted day to day by different causes such as expansion in industrialization, rapid increment in population size, the threat of climate, and growth of urbanization. The existence of a number of organic dyes, detergents, and pesticides from industrial effluents could lead to severe diseases and even to the death of human beings. Currently, remediation of those hazardous organic contaminants using semiconductor metal oxide catalysts has received extensive attention in recent years. Among the numerous nanometal oxides, titanium oxide (TiO₂) nanoparticles (NPs) have been well known as a significant photocatalytic material due to their suitable physiochemical behaviors such as stability, conductivity, high surface area to volume ratio, structure, and porosity nature at the nanoscale level. TiO₂ semiconductor nanoparticles could be synthesized via several physiochemical approaches; among those, the biogenic technique is the most selective one which involves the synthesis of NPs using different templates. Biogenic synthesis of nanoparticles is an environmentally friendly protocol that involves the use of different parts and types of biogenic sources such as bacteria, fungi, yeast, virus, and green plants or the byproducts of their metabolism, which act as both reducing and stabilizing agents. TiO₂ NPs obtained via the biogenic method provide a potential application for the degradation of organic dyes and other pollutants in wastewater. This method of synthesis of NPs has been given a great attention by researchers due to their nontoxicity, low cost, environmental friendliness, the usage of green solvents, and simplicity of the process. This review focuses on summarizing the synthesis of TiO₂ NPs using various biogenic sources, characterization, and their photocatalytic applications for the degradation of different wastes and organic dyes from polluted water.

Impact of titanium dioxide nanoparticles on intestinal community in 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced acute colitis mice and the intervention effect of vitamin E

Titanium dioxide nanoparticles (TiO2-NPs) are widely applied as additives in foods due to their excellent whitening and brightening capability. Although the toxicity and antibacterial activity of TiO2-NPs have been extensively studied, their impact on the gut microbiota in vivo still remains unclear, especially in animals with gastrointestinal disorders. In the present study, healthy mice and TNBS-induced colitis mice were administered with TiO2-NPs (38.3 ± 9.3 nm) orally at a dose of 100 mg per kg bw daily for 10 days to study the impact of TiO2-NPs on the gut microbiota and colitis development. Moreover, the mechanism of TiO2-NPs on the gut microbiota was also discussed when the colitis mice were additionally administered with vitamin E to remove ROS. Changes in the microbiota community structure and gut-associated function prediction were analyzed through bioinformatics. The result showed that the oral administration of TiO2-NPs mitigated colitis symptoms by reducing the DAI and CMDI scores and TNF-α level. Furthermore, 16S rDNA sequencing analysis showed that the structure and function prediction of gut microbiota could be modified in healthy mice and colitis mice after exposure to TiO2-NPs, but the opposite physiological effect occurred since the dominant flora varied in these two groups. Moreover, vitamin E intervention did not change the effects of TiO2-NPs on the microbiota community structure and gut-associated function, which indicates that the mechanism of the biological effects of TiO2-NPs on the gut microbiota may not be associated with their ability to induce the generation of ROS. In summary, our work firstly found that TiO2-NPs could regulate the gut microbiota of colitis mice and participate in the mitigation of TNBS-induced acute colitis, and the capability of TiO2-NPs to induce the generation of ROS inducement did not contribute to this process.

Green Synthesis of Metallic Nanoparticles and Their Prospective Biotechnological Applications: an Overview

The green synthesis of nanoparticles (NPs) using living cells is a promising and novelty tool in bionanotechnology. Chemical and physical methods are used to synthesize NPs; however, biological methods are preferred due to its eco-friendly, clean, safe, cost-effective, easy, and effective sources for high productivity and purity. High pressure or temperature is not required for the green synthesis of NPs, and the use of toxic and hazardous substances and the addition of external reducing, stabilizing, or capping agents are avoided. Intra- or extracellular biosynthesis of NPs can be achieved by numerous biological entities including bacteria, fungi, yeast, algae, actinomycetes, and plant extracts. Recently, numerous methods are used to increase the productivity of nanoparticles with variable size, shape, and stability. The different mechanical, optical, magnetic, and chemical properties of NPs have been related to their shape, size, surface charge, and surface area. Detection and characterization of biosynthesized NPs are conducted using different techniques such as UV-vis spectroscopy, FT-IR, TEM, SEM, AFM, DLS, XRD, zeta potential analyses, etc. NPs synthesized by the green approach can be incorporated into different biotechnological fields as antimicrobial, antitumor, and antioxidant agents; as a control for phytopathogens; and as bioremediative factors, and they are also used in the food and textile industries, in smart agriculture, and in wastewater treatment. This review will address biological entities that can be used for the green synthesis of NPs and their prospects for biotechnological applications.

Controlled and cellulose eco-friendly synthesis and characterization of Bi2O2CO3 quantum dot nanostructures (QDNSs) and drug delivery study

This work aimed to prepare solvent-free or green Bi₂O₂CO₃ for quantum dot nanostructures (QDNSs) based on cellulose as a stabilizer and green capping agent to sorafenib delivery for liver targeting. Because the walnut tree is one of the most abundant trees in Iran, it was tried to synthesize Bi₂O₂CO₃ QDNSs using a walnut skin extract. The saturation magnetization for Bi₂O₂CO₃ QDNSs was calculated to be 68.1. Also, the size of products was measured at around 60–80 nm with the Debye–Scherrer equation. Moreover, the morphology, functional groups, and crystallography of the Bi₂O₂CO₃ nanoparticles were investigated using atomic force microscopy, scanning electron microscopy, vibrating-sample magnetometer, and Uv–vis spectroscopy. The results demonstrated that Bi₂O₂CO₃ QDNSs have opto-magnetic properties and they can be suggested as the candidate materials for the sorafenib delivery on the liver tissue. The optical band gap estimated for Bi₂O₂CO₃ QDNSs was found to be red-shift from 3.22 eV. This study suggests the preparation of the Bi₂O₂CO₃ QDNSs based on cellulose as new opto-magnetic materials at different temperatures of 180 °C, 200 °C, 220 °C, and 240 °C for sorafenib delivery as a type of biological therapy drug.

Active packaging for Salmon stored at refrigerator with Polypropylene nanocomposites containing 4A zeolite, ZnO nanoparticles, and green tea extract

In this study, three types of Polypropylene-based (PP) films (two active nanocomposites and one control film) containing zinc oxide nanoparticles (ZnO NPs), 4A zeolite (4A Z), and green tea extract (GTE) were studied as modern active packaging's that can adjust the release of antimicrobial agents. The influence of PP nanocomposite with 3% (w/w) ZnO NPs/4A Z/GTE (treatment 1) and 6% (w/w) ZnO NPs/4A Z/GTE (treatment 2) on controlling microbial growth and preserving the sensory and chemical qualities of Salmon over nine days of storage at 4 ± 1°C was evaluated. The disk diffusion test revealed inhibition zones in the range of 10.98 ± 0.03 to 13.42 ± 0.01 m for treatments 1 and 2, respectively; the nanocomposite film with 6% ZnO NPs/4A Z/GTE had the highest antimicrobial effect against Gram-negative bacteria (p < .05). Chemical analysis revealed that the initial peroxide value of Salmon was 0.68 ± 0.0 mEq/kg, which increased by day 9 to 12.3 ± 0.03 mEq/kg in the control sample, but rising only to 9.9 ± 0.01 and 7.3 ± 0.02 mEq/kg in treatments 1 and 2, respectively (p < .05). The shelf life of Salmon given treatment 2 increased significantly to nine days relative to the control. Accordingly, these nanocomposite films are promising as new active packaging for preventing microbial growth and preserving the quality of salmon.

Preparation and characterization of titanium dioxide nanoparticles and in vitro investigation of their cytotoxicity and antibacterial activity against Staphylococcus aureus and Escherichia coli

Titanium dioxide nanoparticles (TiO₂ NPs) are photo-active metallic nanoparticles becoming promising agents in modern biomedical applications. Herein, a novel process for the synthesis of TiO₂ NPs with high stability was developed by a sol-gel process and to investigate their cytotoxicity and antibacterial activity. Numerous experiments have been performed to confirm the morphologies, compositions, and physicochemical properties of prepared TiO₂ NPs, such as field emission scanning electron microscopy, dynamic light scattering, Zeta potential, Fourier transform infrared spectroscopy and X-ray diffraction. MTT assay was applied to assess the cytotoxicity of the prepared nanoparticles. The results indicate that the synthesized nanoparticles' diameter is about 68 nm and contains the anatase phase, in the range of 2θ from 25 to 80 °C. The hydrodynamic radius of nanoparticles is about 140.4 nm, and the zeta potential of nanoparticles is about -44.6 mV. The MTT results have not shown any toxicity; the antibacterial inhibitory effect of TiO₂ NPs at 200 mg/mL concentrations exhibited superior antibacterial activity at 15.9 ± 0.1, 14.0 ± 0.1 against Staphylococcus aureus and Escherichia coli, respectively. In conclusion, colloidal solutions with high stability were successfully synthesized, contributing to decreased dimensions and increased antibacterial properties.

Biosynthesis of inorganic nanomaterials using microbial cells and bacteriophages

Inorganic nanomaterials are widely used in chemical, electronics, photonics, energy and medical industries. Preparing a nanomaterial (NM) typically requires physical and/or chemical methods that involve harsh and environmentally hazardous conditions. Recently, wild-type and genetically engineered microorganisms have been harnessed for the biosynthesis of inorganic NMs under mild and environmentally friendly conditions. Microorganisms such as microalgae, fungi and bacteria, as well as bacteriophages, can be used as biofactories to produce single-element and multi-element inorganic NMs. This Review describes the emerging area of inorganic NM biosynthesis, emphasizing the mechanisms of inorganic-ion reduction and detoxification, while also highlighting the proteins and peptides involved. We show how analysing a Pourbaix diagram can help us devise strategies for the predictive biosynthesis of NMs with high producibility and crystallinity and also describe how to control the size and morphology of the product. Here, we survey biosynthetic inorganic NMs of 55 elements and their applications in catalysis, energy harvesting and storage, electronics, antimicrobials and biomedical therapy. Furthermore, a step-by-step flow chart is presented to aid the design and biosynthesis of inorganic NMs employing microbial cells. Future research in this area will add to the diversity of available inorganic NMs but should also address scalability and purity.

Phyto-Mediated Synthesis of Porous Titanium Dioxide Nanoparticles From Withania somnifera Root Extract: Broad-Spectrum Attenuation of Biofilm and Cytotoxic Properties Against HepG2 Cell Lines

There is grave necessity to counter the menace of drug-resistant biofilms of pathogens using nanomaterials. Moreover, we need to produce nanoparticles (NPs) using inexpensive clean biological approaches that demonstrate broad-spectrum inhibition of microbial biofilms and cytotoxicity against HepG2 cell lines. In the current research work, titanium dioxide (TiO2) NPs were fabricated through an environmentally friendly green process using the root extract of Withania somnifera as the stabilizing and reducing agent to examine its antibiofilm and anticancer potential. Further, X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron micrograph (TEM), energy-dispersive X-ray spectroscopy (EDS), dynamic light scattering (DLS), thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) techniques were used for determining the crystallinity, functional groups involved, shape, size, thermal behavior, surface area, and porosity measurement, respectively, of the synthesized TiO2 NPs. Antimicrobial potential of the TiO2 NPs was determined by evaluating the minimum inhibitory concentration (MIC) against Escherichia coli, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, Listeria monocytogenes, Serratia marcescens, and Candida albicans. Furthermore, at levels below the MIC (0.5 × MIC), TiO2 NPs demonstrated significant inhibition of biofilm formation (43-71%) and mature biofilms (24-64%) in all test pathogens. Cell death due to enhanced reactive oxygen species (ROS) production could be responsible for the impaired biofilm production in TiO2 NP-treated pathogens. The synthesized NPs induced considerable reduction in the viability of HepG2 in vitro and could prove effective in controlling liver cancer. In summary, the green synthesized TiO2 NPs demonstrate multifarious biological properties and could be used as an anti-infective agent to treat biofilm-based infections and cancer.

Titanium Dioxide Nanoparticles in Food and Personal Care Products-What Do We Know about Their Safety?

Titanium dioxide (TiO2) is a material of diverse applications commonly used as a food additive or cosmetic ingredient. Its prevalence in products of everyday use, especially in nanosize, raises concerns about safety. Current findings on the safety of titanium dioxide nanoparticles (TiO2 NPs) used as a food additive or a sunscreen compound are reviewed and systematized in this publication. Although some studies state that TiO2 NPs are not harmful to humans through ingestion or via dermal exposure, there is a considerable number of data that demonstrated their toxic effects in animal models. The final agreement on the safety of this nanomaterial has not yet been reached among researchers. There is also a lack of official, standardized guidelines for thorough characterization of TiO2 NPs in food and cosmetic products, provided by international authorities. Recent advances in the application of 'green-synthesized' TiO2 NPs, as well as comparative studies of the properties of 'biogenic' and 'traditional' nanoparticles, are presented. To conclude, perspectives and directions for further studies on the toxicity of TiO2 NPs are proposed.

Bactericidal Capacity of a Heterogeneous TiO2/ZnO Nanocomposite against Multidrug-Resistant and Non-Multidrug-Resistant Bacterial Strains Associated with Nosocomial Infections

The surge of medical devices associated with nosocomial infection (NI) cases, especially by multidrug-resistant (MDR) bacterial strains, is one of the pressing issues of present health care systems. Metal oxide nanoparticles (MNPs) have become promising antibacterial agents against a wide range of bacterial strains. This work study is on the bactericidal capacity of heterogeneous TiO₂/ZnO nanocomposites with different weight percentages and concentrations against common MDR and non-MDR bacterial strains. The profiles on disk diffusion, minimum inhibitory concentration, minimum bactericidal concentration, tolerance determination, time-kill, and biofilm inhibition assay were determined after 24 h of direct contact with the nanocomposite samples. Findings from this work revealed that the heterogeneous TiO₂/ZnO nanocomposite with a 25T75Z weight ratio showed an optimal tolerance ratio against Gram-positive and -negative bacteria, indicating their bactericidal capacity. Further observation suggests that higher molar ratio of Zn²⁺ may possibly involve generation of active ion species that enhance bactericidal effect against Gram-positive bacterial strains, especially for the MDR strains. Nano-based technology using MNPs may provide a promising solution for the prevention and control of NIs. Further work on biocompatibility and cytotoxicity profiles of this nanocomposite are needed.

Eco-friendly active packaging consisting of nanostructured biopolymer matrix reinforced with TiO2 and essential oil: Application for preservation of refrigerated meat

Biodegradable active packaging is required to replace petroleum-based plastics. In this study, a biopolymer-based packaging material was prepared using a casting method, which consisted of a cellulose nanofiber/whey protein matrix containing titanium dioxide particles (1% TiO₂) and essential oil droplets (2% rosemary oil) as functional components. The ability of this packaging to protect lamb meat from chemical and microbial spoilage during 15 days of refrigerated storage (4 °C) was analysed. The meat samples were periodically analysed for microbial count, chemical stability (pH, lipid oxidation, lipolysis), and optical properties. The active packaging significantly reduced microbial growth, lipid oxidation, and lipolysis of the lamb meat during storage, which led to an increase in shelf life from around 6 to 15 days. These biopolymer-based active packaging materials may therefore be suitable for application in meat products.