Bacterial Biosynthesis of Gold Nanoparticles Using Salmonella enterica subsp. enterica serovar Typhi Isolated from Blood and Stool Specimens of Patients

Advancing Biosensing Frontiers Through Gold Nanoparticle Engineering: Synthesis Strategies and Detection Paradigms

Gold Nanoparticles (GNPs) play a pivotal role in nanobiotechnology because of their distinct physicochemical traits, such as optical properties, compatibility with biological systems, and their ability to be easily functionalized. The top-down and bottom-up approaches are for the synthesis of GNPs. There are various chemical, physical, and green synthesis techniques, such as chemical reduction, seed-mediated growth, physical ablation method, pyrolysis, sputtering, etc. are some methods for the synthesis of GNPs. The use of plants, algae, fungi, and other microorganisms has recently arisen as a new approach for the eco-friendly synthesis with precise control over NP size, shape, and surface properties. The functionalization strategies involving biomolecules, polymers, and ligands enhance their stability and target specificity, facilitating their integration into biosensors. The detection of biomolecules, pathogens, and environmental toxins with high sensitivity and accuracy is facilitated by multiple signals such as localized surface plasmon resonance (LSPR), alterations in color, and electrochemical characteristics. Furthermore, their role in point-of-care diagnostics, drug delivery, and imaging underscores their versatility in biomedical applications. This review provides a comprehensive overview of recent advancements in the synthesis, functionalization, and GNPs-based biosensors. In addition, the review highlights recent advancements, challenges, and future prospects of GNPs in biosensing and nanomedicine, offering an understanding of diagnostics and therapeutic monitoring. The key challenges include stability, reproducibility, and scalability, and the future focuses on green synthesis with enhanced sensitivity and multiplexed biosensing applications.

A paradigm of microbe-mediated green nano-semiconductors and nano-metals

Semiconducting and metallic nanomaterials are essential building blocks for developing modern-age technologies, and their demand is expanding exponentially with a growing population. However, their processing impacts the ecosystem and requires urgently sustainable solutions. This perspective underlines the emergence of microbe-mediated (bacteria, yeast, fungi, microalgae, viruses, cyanobacteria) green nanomaterials, including metal-based, carbon-based, organic and hybrid nanomaterials, with technical challenges of scalability, stability and cytotoxicity restricting their transition from lab-to-market. Besides, it discusses alternative solutions by integrating digital-age technologies like artificial intelligence to establish these green nano-semiconductors/metals for multidimensional applications and subsidizing the UN's sustainable development goals and one health management.

Pulsed sonodynamic therapy of melanoma cancer cells using nanoparticles of and mesoporous platinum

OBJECTIVE

Noble metal nanomaterials have been introduced as ideal sonosensitizers for sonodynamic therapy (SDT) of cancer. In this research, platinum nanoparticles (PtNPs) and mesoporous platinum (MPt) were first synthesized and then evaluated as novel sonosensitizers.

METHODS

Ultrasound waves were radiated at two different power densities and two different pulse ratios to develop a pulsed radiation route for SDT of the malignant melanoma cell line C540 (B16/F10). Fluorescence emission was recorded as an indicator of intracellular reactive oxygen generation during the treatment.

RESULTS

Platinum nanoparticles had an average diameter of 12 ± 7 nm and a zeta potential of -17.6 mV; also, MPt had a sponge-like and highly porous structure with a pore size <11 nm and a zeta potential of -39.5 mV. Both PtNPs and MPt, particularly the latter, enhanced the rate of inhibition of tumor cell growth on ultrasound radiation at an output power density of 1.0 W cm^-2 and pulse ratio of 30% over 10 min without intensifying temperature.

CONCLUSION

Use of the developed pulsed (rather than continuous) radiation in SDT and PtNPs or MPT, without hyperthermia, resulted in a new effective cancer treatment method based on the mechanisms of cavitation and/or ROS generation.

In vitro anticancer and antibacterial performance of biosynthesized Ag and Ce co-doped ZnO NPs

The great potential of zinc oxide nanoparticles (ZnO NPs) for biomedical applications is attributed to their physicochemical properties. In this work, pure and Ag and Ce dual-doped ZnO NPs were synthesized through a facile and green route to examine their cytotoxicity in breast cancer and normal cells. The initial preparation of dual-doped nanoparticles was completed by the usage of taranjabin. The synthesis of Ag and Ce dual-doped ZnO NPs was started with preparing the Ce:Ag ratios of 1:1, 1:2, and 1:4. The cytotoxicity effects of synthesized nanoparticles against breast normal cells (MCF-10A) and breast cancer cells (MDA-MB-231) were examined. The hexagonal structure of synthesized nanoparticles was observed through the results of X-ray diffraction (XRD). Scanning electron microscopy (SEM) images exhibited the spherical shape and smooth surfaces of prepared particles along with the homogeneous distribution of Ag and Ce in ZnO with high-quality lattice fringes without any distortions. According to the cytotoxic results, the effects of Ag/Ce dual-doped ZnO NPs on breast cancer (MDA-MB-231) cells were significantly more than of pure ZnO NPs, while dual-doped and pure nanoparticles remained indifferent towards breast normal (MCF-10A) cells. In addition, we investigated the antimicrobial activity against harmful bacteria.

Green approaches for the synthesis of metal and metal oxide nanoparticles using microbial and plant extracts

Green synthesis approaches are gaining significance as promising routes for the sustainable preparation of nanoparticles, offering reduced toxicity towards living organisms and the environment. Nanomaterials produced by green synthesis approaches can offer additional benefits, including reduced energy inputs and lower production costs than traditional synthesis, which bodes well for commercial-scale production. The biomolecules and phytochemicals extracted from microbes and plants, respectively, are active compounds that function as reducing and stabilizing agents for the green synthesis of nanoparticles. Microorganisms, such as bacteria, yeasts, fungi, and algae, have been used in nanomaterials' biological synthesis for some time. Furthermore, the use of plants or plant extracts for metal and metal-based hybrid nanoparticle synthesis represents a novel green synthesis approach that has attracted significant research interest. This review discusses various biosynthesis approaches via microbes and plants for the green preparation of metal and metal oxide nanoparticles and provides insights into the molecular aspects of the synthesis mechanisms and biomedical applications. The use of agriculture waste as a potential bioresource for nanoparticle synthesis and biomedical applications of biosynthesized nanoparticles is also discussed.

Microbe-Mediated Extracellular and Intracellular Mineralization: Environmental, Industrial, and Biotechnological Applications

Microbe-mediated mineralization is ubiquitous in nature, involving bacteria, fungi, viruses, and algae. These mineralization processes comprise calcification, silicification, and iron mineralization. The mechanisms for mineral formation include extracellular and intracellular biomineralization. The mineral precipitating capability of microbes is often harnessed for green synthesis of metal nanoparticles, which are relatively less toxic compared with those synthesized through physical or chemical methods. Microbe-mediated mineralization has important applications ranging from pollutant removal and nonreactive carriers, to other industrial and biomedical applications. Herein, the different types of microbe-mediated biomineralization that occur in nature, their mechanisms, as well as their applications are elucidated to create a backdrop for future research.

Survey of cytotoxic and UV protection effects of biosynthesized cerium oxide nanoparticles

Cerium oxide nanoparticles (CeO₂ NPs) are among the important nanoparticles that are extensively utilized in cosmetics, automotive industries, ultraviolet (UV) filtration, gas sensors, and pharmaceutical products. In this study, CeO₂ NPs were synthesized using an aqueous extract of Ziziphus jujube fruit. The synthesized nanoparticles were characterized using UV-visible spectroscopy, powder X-ray diffraction, Fourier transform infrared spectroscopy, energy-dispersive spectroscopy, field energy scanning electron microscopy, and Raman methods. The results indicated that the size of synthesized nanoparticles is between 18 and 25 nm, and they have a spherical shape. UV absorbance of the synthesized nanoparticles was measured through spectrophotometric method in the range of 290 to 320 nm. The cytotoxic activity of synthesized CeO₂ NPs against colon (HT-29) cancer cell line was surveyed through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The results showed that synthesized nanoparticles are nontoxic on HT-29 cells under 400 μg/mL concentrations after 24 hours of treatment time periods. The increase in treatment time cases increases cytotoxic activity of synthesized nanoparticles. Sun protection factor of CeO₂ NPs, as a criterion for amount of sunlight radiation protection, was determined by applying Mansur equation. The results demonstrated that synthesized CeO₂ NPs have excellent UV protection and sunscreen physical absorption properties.

Nickel-doped cerium oxide nanoparticles: biosynthesis, cytotoxicity and UV protection studies

This study was conducted to obtain Ni_xCe_1−xO₂ (where x = 0, 1, 3 and 5% w/w) nanoparticles using Salvadora persica extracts through an easy, inexpensive and non-toxic method. The biosynthesized nanoparticles have been characterized via powder X-ray diffraction (PXRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) spectroscopy, and vibrating-sample magnetometer (VSM) analysis. The results of PXRD showed that Ni doping in the CeO₂ process generated a higher shift at an angle of (111); also, the PXRD patterns were surveyed by the Rietveld refinement technique. Raman analysis revealed that doping nickel in CeO₂ led to the nanoparticles reducing the intensity of the F_2g mode. The FESEM images showed that the particle size was 5–6 nm and it had a spherical shape. The hysteresis loops of the synthesized nanoparticles were similar to that of the normal ferromagnetic materials. The cytotoxic activity of the synthesized undoped and Ni-doped CeO₂-NPs was determined using MTT assays against a colon cancer cell line (HT-29). The results showed that the cytotoxic effect of the synthesized nanoparticles changed after doping nickel in CeO₂-NPs. The increase in the Ni-doping value for CeO₂-NPs increased the cytotoxic activity. The sun protection factor (SPF) has been estimated through spectrophotometric measurements for determining UV protection. This showed that increasing the percentage of nickel in the doped nanoparticles increased the protection factor and a higher SPF value was obtained: 48.52.

This study was conducted to obtain Ni_xCe_1−xO₂ (where x = 0, 1, 3 and 5% w/w) nanoparticles using Salvadora persica extracts through an easy, inexpensive and non-toxic method.

Carbon@polypyrrole nanotubes as a photosensitizer in laser phototherapy of Pseudomonas aeruginosa

Phototherapy has been offered as an alternative and promising antibacterial strategy to overcome the antibiotic resistance problem. This study evaluated the antibacterial and phototherapy effects of carbon nanotubes with a polypyrrole coating in a core@shell structure (CNTs@PPy) on Pseudomonas aeruginosa (P. aeruginosa). P. aeruginosa was treated with CNTs@PPy at different concentrations (50-500 μg mL^-1) in dark or laser light irradiation with a wavelength of 808 nm, a power density of 1000 mW cm^-2 for 20 min. Temperature increment, cell viability, formation of reactive oxygen species (ROS) and protein/nucleic acid leakage subsequent the P. aeruginosa treatment were evaluated. The results showed that near-infrared laser irradiation of CNTs@PPy caused to a temperature increment confirming the ability of powerful photokilling of P. aeruginosa in a photothermal route. On the other hand, while CNTs@PPy represented just a 30-50% P. aeruginosa killing rate in dark, laser irradiation of 250 and 500 μg mL^-1 concentrations of CNTs@PPy resulted in a ˜70% P. aeruginosa killing rate, along with significant ROS production into the medium and protein and nucleic acid leakage from P. aeruginosa. These later effects were assigned to a photodynamic route activity of CNTs@PPy upon laser irradiation. Therefore, CNTs@PPy acted as a photosensitizer in both photothermal and photodynamic therapies to present an enhanced bactericidal activity to annihilate and destroyed the gram-negative bacteria P. aeruginosa, a cause of many infectious diseases.

Biosynthesis of bimetallic and core-shell nanoparticles: their biomedical applications - a review

Recently, researchers succeeded in designing and manufacturing a new class of nanoparticles (NPs) called hybrid NPs. Among hybrid NPs, bimetallic and core-shell NPs were a revolutionary step in NPs science. A large number of green physiochemical and methods for nanostructures synthesis have been published. Eventually, physiochemical methods are either expensive or require the use of chemical compounds for the synthesis of bimetallic and core-shell nanostructures. The main challenges that scientists are facing are making the process cheaper, facile and eco-friendly efficient synthesis process. Green synthesis (biosynthesis) refers to the use of bio-resources (such as bacteria, fungi, plants or their derivatives) for the synthesis of nanostructures. The popularity of the green synthesis of nanostructures is due to their environmental friendliness and no usage of toxic materials, environmental friendliness for the synthesis or stability of nanostructure. Bimetallic and core-shell NPs have many biomedical applications such as removing heavy metals, parasitology, molecular and microbial sensor, gene carrier, single bacterial detection, oligonucleotide detection and so on. The purpose of this study is to discuss briefly the biosynthesised bimetallic and core-shell NPs, their biomedical applications.

Core@shell Nanoparticles: Greener Synthesis Using Natural Plant Products

Among an array of hybrid nanoparticles, core-shell nanoparticles comprise of two or more materials, such as metals and biomolecules, wherein one of them forms the core at the center, while the other material/materials that were located around the central core develops a shell. Core-shell nanostructures are useful entities with high thermal and chemical stability, lower toxicity, greater solubility, and higher permeability to specific target cells. Plant or natural products-mediated synthesis of nanostructures refers to the use of plants or its extracts for the synthesis of nanostructures, an emerging field of sustainable nanotechnology. Various physiochemical and greener methods have been advanced for the synthesis of nanostructures, in contrast to conventional approaches that require the use of synthetic compounds for the assembly of nanostructures. Although several biological resources have been exploited for the synthesis of core-shell nanoparticles, but plant-based materials appear to be the ideal candidates for large-scale green synthesis of core-shell nanoparticles. This review summarizes the known strategies for the greener production of core-shell nanoparticles using plants extract or their derivatives and highlights their salient attributes, such as low costs, the lack of dependence on the use of any toxic materials, and the environmental friendliness for the sustainable assembly of stabile nanostructures.

Leishmanicidal Activity of Biogenic Fe₃O₄ Nanoparticles

Abstract: Due to the multiplicity of useful applications of metal oxide nanoparticles (ONPs) in medicine are growing exponentially, in this study, Fe₃O₄ (iron oxide) nanoparticles (IONPs) were biosynthesized using Rosemary to evaluate the leishmanicidal efficiency of green synthesized IONPs. This is the first report of the leishmanicidal efficiency of green synthesized IONPs against Leishmania major. The resulting biosynthesized IONPs were characterized by ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). The leishmanicidal activity of IONPS was studied via 3-4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results showed the fabrication of the spherical shape of monodisperse IONPs with a size 4 ± 2 nm. The UV-visible spectrophotometer absorption peak was at 334 nm. The leishmanicidal activity of biogenic iron oxide nanoparticles against Leishmania major (promastigote) was also studied. The IC₅₀ of IONPs was 350 µg/mL. In this report, IONPs were synthesized via a green method. IONPs are mainly spherical and homogeneous, with an average size of about 4 nm, and were synthesized here using an eco-friendly, simple, and inexpensive method.

A novel in vitro transformation of Lepidium draba L. using rapid direct shoot regeneration

The present research is carried out to study Lepidium draba gene transformation for the first time, using direct shoot explants. As a prerequisite for gene transformation, the regeneration conditions in L. draba were optimized. We achieved an efficient and reproducible protocol for successful direct shoot regeneration without intervening callus formation. The results indicate that L. draba is the insistent species of Brassicaceae in direct shoot regeneration. Various explants of L. draba were genetically transformed with different strains of Agrobacterium tumefaciens, viz., LBA4404, GV3850, GV3101, and EHA105, using the vector pBI121. Expression of GUS reporter protein was assayed by histochemical staining. In addition, using the PCR method with specific primers proved the integration of GUS gene into the plants. The highest transformation efficiency was achieved with Agrobacterium strain GV3850. Moreover, we found that infected hypocotyl and root explants of L. draba interestingly yielded higher transformation efficiency, so that in hypocotyls on average exceeded 70% of the explants. This study showed that L. draba, in addition to the numerous desirable traits, has a high potential for gene transfer.

Biosynthesis of Silver Nanoparticles Using Pine Pollen and Evaluation of the Antifungal Efficiency

Background: Nanoparticles have been applied to medicine, hygiene, pharmacy and dentistry, and will bring significant advances in the prevention, diagnosis, drug delivery and treatment of disease. Green synthesis of metal nanoparticles has a very important role in nanobiotechnology, allowing production of non-toxic and eco-friendly particles. Objectives: Green synthesis of silver nanoparticles (AgNPs) was studied using pine pollen as a novel, cost-effective, simple and non-hazardous bioresource. The antifungal activity of the synthesized AgNPs was investigated in vitro. Materials and Methods: Biosynthesis of AgNPs was conducted using pollen of pine (as a novel bioresource) acting as both reducing and capping agents. AgNPs were characterized using UV-visible spectroscopy, X-ray diffraction and transmission electron microscopy. In evaluation for antifungal properties, the synthesized AgNPs represented significant in vitro inhibitory effects on Neofusicoccum parvum cultures. Results: Pine pollen can mediate biosynthesis of colloidal AgNPs with an average size of 12 nm. AgNPs were formed at 22 °C and observed to be highly stable up to three months without precipitation or decreased antifungal property. AgNPs showed significant inhibitory effects against Neofusicoccum parvum. Conclusion: The first report for a low-cost, simple, well feasible and eco-friendly procedure for biosynthesis of AgNPs was presented. The synthesized AgNPs by pine pollen were nontoxic and eco-friendly, and can be employed for large-scale production. The nanoparticles showed strong effect on quantitative inhibition and disruption of antifungal growth.