Biosynthesis of luminescent CdS quantum dots using plant hairy root culture

Remediation of phenanthrene by highly efficient CdS-SnS photocatalyst and its cytotoxic assessments

Cadmium sulfide-tin sulfide (CdS-SnS) nanoparticles are a novel kind of photocatalyst. These CdS-SnS nanoparticles are synthesized and characterized using UV-Vis, FT-IR, XRD, SEM-EDX, and DLS techniques, to understand their size distribution, crystalline nature, morphology, shape, optical properties, and elemental composition. This research offers insight into the efficient photocatalytic degradation of Phenanthrene (PHE) using CdS-SnS. The CdS-SnS NPs as photocatalyst can effectively photodegrade the polycyclic aromatic hydrocarbons (PAH) such as phenanthrene under simulated solar and UV light. UV-vis spectra of these nanoparticles exhibit peaks at 365 and 546 cm-1 respectively, the mean size of the CdS-SnS NPs in DLS is determined to be 78 nm. The CdS-SnS stretching frequency was observed at wave numbers below 700 cm-1, the absorption peak at 1123 cm-1 indicates the presence of C-N stretch or CS bond of thiourea, while the peak at 1350.38 cm-1 corresponds to the tris-amine C-N stretch in FT-IR. Additionally, the peaks observed at 2026 cm-1 indicate the presence of isothiocyanate (NCS). 1456.23 cm-1 represents the asymmetric scissor deformation vibration. EDAX revealed the presence of elemental Cd and Sn oxides. The antimicrobial studies showed that the CdS-SnS NPs at the concentration of 150 μg/mL, exhibit maximum inhibition (15 ± 1.25 mm) against the strains Proteus mirabilis followed by Staphylococcus epidermidis and Clostridium spp. Among fungal strains Colletotrichum spp. exhibits the maximum zone of inhibition (9 ± 0.25). This research also observed the cytotoxic effects of CdS-SnS NPs on HepG2 and ZF4 cells. HepG2 cells exhibited 50% inhibition at 50 μg/mL and 70% inhibition at 100 μg/mL concentrations, while ZF4 cells exhibited 50% inhibition at 50 μg/mL and 78% inhibition at 100 μg/mL concentrations, respectively. The parameters like concentration of PHE, concentration of CdS-SnS NPs, pH, and sources of irradiation on batch adsorption were examined to maximize the efficiency of the photodegradation process.

Photocatalytic, Antibacterial, Cytotoxic and Bioimaging Applications of Fluorescent CdS Nanoparticles Prepared in DNA Biotemplate

Synthesizing nanoparticles in biotemplates has been cited as one of the most promising way to obtain monodispersed inorganic nanoparticles. In this method, uniform voids in porous materials serve as hosts to confine the synthesized nanoparticles. DNA template can be described as a smart glue for assembling nanoscale building blocks. Here we investigate the photocatalytic, antibacterial, cytotoxic, and bioimaging applications of DNA capped CdS. XRD, SEM, TEM, UV-visible absorption, and photoluminescence spectra were used to study structural, morphological, and optical properties of CdS nanoparticles. Prepared CdS nanoparticles exhibit visible fluorescence. The photocatalytic activity of CdS towards Rhodamine 6G and Methylene blue are 64% and 91% respectively. A disc-diffusion method is used to demonstrate antibacterial screening. It was shown that CdS nanoparticles inhibit Gram-positive bacteria and Gram-negative bacteria effectively. DNA capped CdS shows higher activity than uncapped CdS nanoparticles. MTT cell viability assays were carried out in HeLa cells to investigate the cytotoxicity for 24 h. At a concentration 2.5 µg/ml, it shows 84% cell viability and 43% viability at 12.5 µg/ml. The calculated LC50 value is equal to 8 µg/ml. These DNA capped CdS nanoparticles were taken for an in-vitro experiment with HeLa cells to exhibit the possibility of bioimaging applications. The present study suggests that the synthesized CdS nanoparticles could be a potential photocatalyst, antibacterial agent, and biocompatible nanoparticle for bioimaging applications.

Synthesis of water-soluble CdS quantum dots for the fluorescence detection of tetracycline

An effective strategy for combating antibiotic-resistant bacteria (ARB) entails the early detection of antibiotics during the initial stages of water treatment facilities. In this context, cadmium sulfide quantum dots (CdS QDs) were employed for the precise detection of tetracycline (TET), an emerging contaminant, in water. CdS QDs with fluorescence properties were synthesized by culturing Citrobacter freundii bacteria. The CdS QDs were characterized by spectroscopy techniques, and the quantum efficiency was estimated to be 55.8% which is ∼2-fold high compared to the standard rhodamine-B solution. The fluorescence of CdS QDs was quenched at 440 nm in the presence of TET. The linear range of TET was varied from 10 to 100 μM with a lower limit of detection of ∼23 nM. The CdS QDs were used to detect TET in river water, tap water, and milk which showed an excellent recovery rate. Therefore, the novel biosynthesis CdS QDs can be a significant fluorescence probe for the detection of TET that shows exceptional sensitivity and selectivity.

Photocatalytic and Enhanced Biological Activities of Schiff Base Capped Fluorescent CdS Nanoparticles

In the present work, biocompatible CdS nanoparticles were synthesized using Schiff base ligand, 3-((2-(-(1-(2hydroxyphenyl)ethylidene)amino)ethyl)imino)-2-pentone, by a simple ultrasonic irradiation method. The structural, morphological, and optical properties were studied using XRD, SEM, TEM, UV-visible absorption, and photoluminescence (PL) spectra. The quantum confinement effect of the Schiff base capped CdS nanoparticles was confirmed by using UV-visible and PL spectrum analysis. This CdS nanoparticles were an effective photocatalyst for degrading rhodamine 6G and methylene blue with a 70% and 98% degradation capacity, respectively. Furthermore, the disc-diffusion method demonstrated that CdS nanoparticles inhibit G-positive bacteria and G-negative bacteria more effectively. These Schiff base capped CdS nanoparticles were taken for an in-vitro experiment with HeLa cells to exhibit the possibility of providing optical probes in biological applications and observed under a fluorescence microscope. In addition, MTT cell viability assays were carried out to investigate the cytotoxicity for 24 h. As a result of this study, 2.5 µg/ml doses of CdS nanoparticles are suitable for imaging and are effective in destroying HeLa cells. The present study suggests that the synthesized Schiff base capped CdS nanoparticles could be a potential photocatalyst, antibacterial agent, and biocompatible nanoparticle for bioimaging applications.

Biosynthesis of Quantum Dots and Their Therapeutic Applications in the Diagnosis and Treatment of Cancer and SARS-CoV-2

Quantum dots (QDs) are semiconductor materials that range from 2 nm to 10 nm. These nanomaterials (NMs) are smaller and have more unique properties compared to conventional nanoparticles (NPs). One of the unique properties of QDs is their special optoelectronic properties, making it possible to apply these NMs in bioimaging. Different size and shape QDs, which are used in various fields such as bioimaging, biosensing, cancer therapy, and drug delivery, have so far been produced by chemical methods. However, chemical synthesis provides expensive routes and causes serious environmental and health issues. Therefore, various biological systems such as bacteria, fungi, yeasts, algae, and plants are considered as potent eco-friendly green nanofactories for the biosynthesis of QDs, which are both economic and environmentally safe. The review aims to provide a descriptive overview of the various microbial agents for the synthesis of QDs and their biomedical applications for the diagnosis and treatment of cancer and SARS-CoV-2.

Emerging Roles of Green-Synthesized Chalcogen and Chalcogenide Nanoparticles in Cancer Theranostics

The last few decades have seen an overwhelming increase in the amount of research carried out on the use of inorganic nanoparticles. More fascinating is the tremendous progress made in the use of chalcogen and chalcogenide nanoparticles in cancer theranostics. These nanomaterials, which were initially synthesized through chemical methods, have now been efficiently produced using different plant materials. The paradigm shift towards the biogenic route of nanoparticle synthesis stems from its superior advantages of biosafety, eco-friendliness, and simplicity, among others. Despite a large number of reviews available on inorganic nanoparticle synthesis through green chemistry, there is currently a dearth of information on the green synthesis of chalcogens and chalcogenides for cancer research. Nanoformulations involving chalcogens such as sulfur, selenium, and tellurium and their respective chalcogenides have recently emerged as promising tools in cancer therapeutics and diagnosis. Similar to other inorganic nanoparticles, chalcogens and chalcogenides have been synthesized using plant extracts and their purified biomolecules. In this review, we provide an up-to-date discussion of the recent progress that has been made in the plant-mediated synthesis of chalcogens and chalcogenides with a special focus on their application in cancer theranostics.

Interaction Properties of Biosynthesized Cadmium Sulphide Quantum Dots with Human Serum Albumin: Further Investigation of Antibacterial Activities and Sensing Applications

Synthesis of low dimensional quantum dots (QDs) (1-10 nm) via green route has garnered great interest having the prospective use in many biological applications (diagnosis, drug delivery and in vivo sensing), which is difficult to achieve by chemical synthesize methods having larger QDs particles or hazardous reagents required for synthesizing of QDs. Here, we have synthesized biogenic cadmium sulphide (CdS) QDs using green tea extract as reducing agents that were homogeneous and smaller size particles 2-4 nm. We also elucidate the (a) protein binding, (b) antibacterial and (c) sensing applications of biogenic CdS QDs in this present work. The biosynthesized CdS QDs were found to have extensive antibacterial activity against both gram-negative E. coli and gram-positive E. faecalis bacterial strains. Since the introduction of QDs in biological media, they can form protein-QDs complex; hence we investigate the binding interaction of CdS QDs with the carrier protein human serum albumin (HSA) in vitro. The synthesized CdS QDs quenched the intrinsic fluorescence of HSA through static quenching mechanism and binding constant (K_b ) was found in order of 10⁴ M^-1 . It was also observed that presence of biogenic CdS QDs affects the HSA-ligand interactions in vitro. The synthesized CdS showed highly effective sensors for tetracycline, rifampicin and bilirubin with LOD values of 99, 141 and 29 ng/mL respectively.

Biogenic Sulfur-Based Chalcogenide Nanocrystals: Methods of Fabrication, Mechanistic Aspects, and Bio-Applications

Bio-nanotechnology has emerged as an efficient and competitive methodology for the production of added-value nanomaterials (NMs). This review article gathers knowledge gleaned from the literature regarding the biosynthesis of sulfur-based chalcogenide nanoparticles (S-NPs), such as CdS, ZnS and PbS NPs, using various biological resources, namely bacteria, fungi including yeast, algae, plant extracts, single biomolecules, and viruses. In addition, this work sheds light onto the hypothetical mechanistic aspects, and discusses the impact of varying the experimental parameters, such as the employed bio-entity, time, pH, and biomass concentration, on the obtained S-NPs and, consequently, on their properties. Furthermore, various bio-applications of these NMs are described. Finally, key elements regarding the whole process are summed up and some hints are provided to overcome encountered bottlenecks towards the improved and scalable production of biogenic S-NPs.

Synthesis, Properties and Bioimaging Applications of Silver-Based Quantum Dots

Ag-based quantum dots (QDs) are semiconductor nanomaterials with exclusive electrooptical properties ideally adaptable for various biotechnological, chemical, and medical applications. Silver-based semiconductor nanocrystals have developed rapidly over the past decades. They have become a promising luminescent functional material for in vivo and in vitro fluorescent studies due to their ability to emit at the near-infrared (NIR) wavelength. In this review, we discuss the basic features of Ag-based QDs, the current status of classic (chemical) and novel methods ("green" synthesis) used to produce these QDs. Additionally, the advantages of using such organisms as bacteria, actinomycetes, fungi, algae, and plants for silver-based QDs biosynthesis have been discussed. The application of silver-based QDs as fluorophores for bioimaging application due to their fluorescence intensity, high quantum yield, fluorescent stability, and resistance to photobleaching has also been reviewed.

Tumor-targeting inorganic nanomaterials synthesized by living cells

Inorganic nanomaterials (NMs) have shown potential application in tumor-targeting theranostics, owing to their unique physicochemical properties. Some living cells in nature can absorb surrounding ions in the environment and then convert them into nanomaterials after a series of intracellular/extracellular biochemical reactions. Inspired by that, a variety of living cells have been used as biofactories to produce metallic/metallic alloy NMs, metalloid NMs, oxide NMs and chalcogenide NMs, which are usually automatically capped with biomolecules originating from the living cells, benefitting their tumor-targeting applications. In this review, we summarize the biosynthesis of inorganic nanomaterials in different types of living cells including bacteria, fungi, plant cells and animal cells, accompanied by their application in tumor-targeting theranostics. The mechanisms involving inorganic-ion bioreduction and detoxification as well as biomineralization are emphasized. Based on the mechanisms, we describe the size and morphology control of the products via the modulation of precursor ion concentration, pH, temperature, and incubation time, as well as cell metabolism by a genetic engineering strategy. The strengths and weaknesses of these biosynthetic processes are compared in terms of the controllability, scalability and cooperativity during applications. Future research in this area will add to the diversity of available inorganic nanomaterials as well as their quality and biosafety.

Pleurotus Macrofungi-Assisted Nanoparticle Synthesis and Its Potential Applications: A Review

Research and innovation in nanoparticles (NPs) synthesis derived from biomaterials have gained much attention due to their unique characteristics, such as low-cost, easy synthesis methods, high water solubility, and eco-friendly nature. NPs derived from macrofungi, including various mushroom species, such as Agaricus bisporus, Pleurotus spp., Lentinus spp., and Ganoderma spp. are well known to possess high nutritional, immune-modulatory, antimicrobial (antibacterial, antifungal and antiviral), antioxidant, and anticancerous properties. Fungi have intracellular metal uptake ability and maximum wall binding capacity; because of which, they have high metal tolerance and bioaccumulation ability. Primarily, two methods have been comprehended in the literature to synthesize metal NPs from macrofungi, i.e., the intracellular method, which refers to NP synthesis inside fungal cells by transportation of ions in the presence of enzymes; and the extracellular method, which refers to the treatment of fungal biomolecules aqueous filtrate with a metal precursor. Pleurotus derived metal NPs are known to inhibit the growth of numerous foodborne pathogenic bacteria and fungi. To the best of our knowledge, there is no such review article reported in the literature describing the synthesis and complete application and mechanism of NPs derived from macrofungi. Herein, we intend to summarize the progressive research on macrofungi derived NPs regarding their synthesis as well as applications in the area of antimicrobial (antibacterial & antifungal), anticancer, antioxidant, catalytic and food preservation. Additionally, the challenges associated with NPs synthesis will also be discussed.

In Vivo Biosynthesis of Inorganic Nanomaterials Using Eukaryotes-A Review

Bionanotechnology, the use of biological resources to produce novel, valuable nanomaterials, has witnessed tremendous developments over the past two decades. This eco-friendly and sustainable approach enables the synthesis of numerous, diverse types of useful nanomaterials for many medical, commercial, and scientific applications. Countless reviews describing the biosynthesis of nanomaterials have been published. However, to the best of our knowledge, no review has been exclusively focused on the in vivo biosynthesis of inorganic nanomaterials. Therefore, the present review is dedicated to filling this gap by describing the many different facets of the in vivo biosynthesis of nanoparticles (NPs) using living eukaryotic cells and organisms-more specifically, live plants and living biomass of several species of microalgae, yeast, fungus, mammalian cells, and animals. It also highlights the strengths and weaknesses of the synthesis methodologies and the NP characteristics, bio-applications, and proposed synthesis mechanisms. This comprehensive review also brings attention to enabling a better understanding between the living organisms themselves and the synthesis conditions that allow their exploitation as nanobiotechnological production platforms as these might serve as a robust resource to boost and expand the bio-production and use of desirable, functional inorganic nanomaterials.

Toxicity Evaluation of Quantum Dots (ZnS and CdS) Singly and Combined in Zebrafish (Danio rerio)

The exponential growth of nanotechnology has led to the production of large quantities of nanomaterials for numerous industrial, technological, agricultural, environmental, food and many other applications. However, this huge production has raised growing concerns about the adverse effects that the release of these nanomaterials may have on the environment and on living organisms. Regarding the effects of QDs on aquatic organisms, existing data is scarce and often contradictory. Thus, more information is needed to understand the mechanisms associated with the potential toxicity of these nanomaterials in the aquatic environment. The toxicity of QDs (ZnS and CdS) was evaluated in the freshwater fish Danio rerio. The fishes were exposed for seven days to different concentrations of QDs (10, 100 and 1000 µg/L) individually and combined. Oxidative stress enzymes (catalase, superoxide dismutase and glutathione S-transferase), lipid peroxidation, HSP70 and total ubiquitin were assessed. In general, results suggest low to moderate toxicity as shown by the increase in catalase activity and lipid peroxidation levels. The QDs (ZnS and CdS) appear to cause more adverse effects singly than when tested combined. However, LPO results suggest that exposure to CdS singly caused more oxidative stress in zebrafish than ZnS or when the two QDs were tested combined. Levels of Zn and Cd measured in fish tissues indicate that both elements were bioaccumulated by fish and the concentrations increased in tissues according to the concentrations tested. The increase in HSP70 measured in fish exposed to 100 µg ZnS-QDs/L may be associated with high levels of Zn determined in fish tissues. No significant changes were detected for total ubiquitin. More experiments should be performed to fully understand the effects of QDs exposure to aquatic biota.

Biogenic nanomaterials: Synthesis, characterization, growth mechanism, and biomedical applications

The biosynthesis of nanomaterials is a huge and intensifying field of research due to their application in various areas, in particular the biomedical and pharmaceutical fields. In this review, we focused on the biosynthesis of both metallic and semiconductor nanomaterials and their application in biomedicine and pharmaceutics. In order to meet an exponentially increasing need for nanostructured materials, the biological route for the synthesis of nanomaterials will have to be explored, offering advantages over chemical and physical methods as a simpler, more cost effective, and environmentally friendly method, and for which there is no need to use high pressure and temperatures or toxic chemicals. This review discusses in detail the potential role of bioreducing and capping/stabilizing agents in biosynthesis. This review also investigates the application of various biosynthetic nanomaterials as antimicrobial materials, in clinical detection, for drug delivery and wound-healing, and as anti-diabetic materials.

Biosynthetic Mechanism of Luminescent ZnO Nanocrystals in the Mammalian Blood Circulation and Their Functionalization for Tumor Therapy

The biosynthesis of nanoparticles in bioreactors using microbial, plant, or animal cells is at the forefront of nanotechnology. We demonstrated for the first time that luminescent, water-soluble ZnO nanocrystals (bio-ZnO NCs) can be spontaneously biosynthesized in the mammalian blood circulation, not in cells, when animals were fed with Zn(CH₃COO)₂ aqueous solution. Serum albumin, rather than metallothioneins or glutathione, proved to play the pivotal role in biosynthesis. The bio-ZnO NCs were gradually taken up in the liver and degraded and excreted in the urine. Thus, we propose that in mammals such as rodents, bovinae, and humans, excess metal ions absorbed into the cardiovascular system via the intestine can be transformed into nanoparticles by binding to serum albumin, forming a "provisional metal-pool", to reduce the toxicity of free metal ions at high concentration and regulate metal homeostasis in the body. Furthermore, the bio-ZnO NCs, which showed favorable biocompatibility, were functionalized with the anticancer drug daunorubicin and effectively achieved controlled drug release mediated by intracellular glutathione in tumor xenograft mice.

Fluorescent CdSe QDs containing Bacillus licheniformis bioprobes for Copper (II) detection in water

Quantum dots (QDs) are semiconductor nanoparticles (NPs) that offer valuable functionality for cellular labeling, drug delivery, solar cells and quantum computation. In this study, we reported that CdSe QDs could be bio-synthesized in Bacillus licheniformis. After optimization, the obtained CdSe QDs exhibited a uniform particle size of 3.71±0.04nm with a maximum fluorescence emission wavelength at 550nm and the synthetical positive ratio can reach up to 87%. Spectral properties, constitution, particle sizes and crystalline phases of the CdSe QDs were systematically and integrally investigated. The CdSe QD-containing Bacillus licheniformis cells were further used as whole fluorescent bio-probes to detect copper (II) (Cu²⁺) in water, which demonstrated a low limit of detection (0.91μM). The assay also showed a good selectivity for Cu²⁺ over other ions including Al³⁺, Cd²⁺, Mg²⁺, K⁺, Na⁺, NH₄⁺, Zn²⁺, CH₃COO⁺, Pb²⁺ and I^-. Our study suggests the fluorescent CdSe QDs-containing Bacillus licheniformis bio-probes as a promising approach for detection of Cu²⁺ in complex solution environment.

Biosynthesis of Inorganic Nanoparticles: A Fresh Look at the Control of Shape, Size and Composition

Several methodologies have been devised for the design of nanomaterials. The "Holy Grail" for materials scientists is the cost-effective, eco-friendly synthesis of nanomaterials with controlled sizes, shapes and compositions, as these features confer to the as-produced nanocrystals unique properties making them appropriate candidates for valuable bio-applications. The present review summarizes published data regarding the production of nanomaterials with special features via sustainable methodologies based on the utilization of natural bioresources. The richness of the latter, the diversity of the routes adopted and the tuned experimental parameters have led to the fabrication of nanomaterials belonging to different chemical families with appropriate compositions and displaying interesting sizes and shapes. It is expected that these outstanding findings will encourage researchers and attract newcomers to continue and extend the exploration of possibilities offered by nature and the design of innovative and safer methodologies towards the synthesis of unique nanomaterials, possessing desired features and exhibiting valuable properties that can be exploited in a profusion of fields.

Comparative study on toxicity of extracellularly biosynthesized and laboratory synthesized CdTe quantum dots

Nanobiosynthesis belongs to the most recent methods for synthesis of nanoparticles. This type of synthesis provides many advantages including the uniformity in particle shape and size. The biosynthesis has also a significant advantage regarding chemical properties of the obtained particles. In this study, we characterized the basic properties and composition of quantum dots (QDs), obtained by the extracellular biosynthesis by Escherichia coli. Furthermore, the toxicity of the biosynthesized QDs was compared to QDs prepared by microwave synthesis. The obtained results revealed the presence of cyan CdTe QDs after removal of substantial amounts of organic compounds, which stabilized the nanoparticle surface. QDs toxicity was evaluated using three cell lines Human Foreskin Fibroblast (HFF), Human Prostate Cancer cells (PC-3) and Breast Cancer cells (MCF-7) and the MTT assay. The test revealed differences in the toxicity between variants of QDs, varying about 10% in the HFF and 30% in the MCF-7 cell lines. The toxicity of the biosynthesized QDs to the PC-3 cell lines was about 35% lower in comparison with the QDs prepared by microwave synthesis.