A review on synthesis of quantum dots and their biomedical applications

Quantum Dots (QDs) are ultra-fine nanometer-sized semiconductor particles with a core-shell structure possess both electrical and optical properties. Their unique ability to emit pure, monochromatic light on being exposed to light makes them extremely versatile in their applications. The color of the light emitted directly depends on their size and shape. Smaller QDs emit shorter wavelengths, closer to the violet end of the visible light spectrum (~380-450 nm), while larger QDs emit longer wavelengths i.e in reddish spectrum (~620-750 nm). Owing to their “tunability”, QDs can be exploited in a wide range of fluorescent, photonic, and electrochemical applications. QDs represent elements mainly from Group II-VI (e.g., CdSe) or Group III-V (e.g., InP) with the resultant optical and electronic properties of the quantum dots being somewhere between bulk semiconductor material and individual atoms or molecules. Besides applications in energy and photonics, they are under extensive investigation and development for use in disease diagnosis and therapy, specifically in the area of controlled drug delivery, biosensing and imaging. This review surveys the progress of research explores their properties, synthesis, applications, delivery systems in biology, and their toxicity

Utilization of dynamic light scattering to evaluate Pterodon emarginatus oleoresin-based nanoemulsion formation by non-heating and solvent-free method

Abstract Pterodon emarginatus Vogel, Fabaceae, is a great source of bioactive compounds. The most known and studied herbal derivative from this species is an ambar-colored oleoresin that contains vouacapane diterpenes and volatile terpenoids, such as β-caryophyllene. Some recent papers aimed to generate nanoemulsions using this oleoresin for biological applications. However, they used high-energy methods that elevate costs of the process or heating procedures, which offer the disadvantage of possible volatile substances loss. Thus, as part of our ongoing studies with nanobiotechnology of natural products, especially regarding preparation of nanoemulsions with promising plant-based oils by low cost and low energy methods, we decided to evaluate the ability of non-heating and solvent-free method to generate P. emarginatus oleoresin-based nanoemulsions. Two non-ionic surfactants were used to generate the nanoemulsions by a simple homogenization method with vortex stirrer. Low mean droplet size (<180 nm) and low polydispersity index (<0.200) were observed even after one day of preparation. The low coefficient of variation for the analyzed parameters of different batches and similar profile for droplet size distribution suggested reproducibility of the method. After 30 days, some degree of droplet growth was observed on nanoemulsion prepared with polyethyleneglycol 400 monooleate, while almost no alteration was observed for nanoemulsion prepared with polysorbate 85. Programmed temperature ramp analysis revealed that no major effects on droplet size and polydispersity index were observed, suggesting the robustness of formed nanoemulsions. Thus, the present study shows for the first time the formation of sucupira-based nanoemulsions by a simple, low cost and ecofriendly method. This study opens new perspectives for bioactive evaluation of this novel nano-product.

Phytofabrication of silver nanoparticles using Myriostachya wightiana as a novel bioresource, and evaluation of their biological activities

ABSTRACT Nanobiotechnology deals with the properties of nanomaterials and their potential uses. Here we report for the first time novel, cost-effective and eco-friendly method for the rapid green synthesis of silver nanoparticles (AgNPs) using leaf extracts of Myriostachya wightiana. The growth of silver nanoparticles was monitored by UV-vis spectroscopy complemented by Zeta potential, dynamic light scattering technique (DLS), Fourier-transform infrared spectroscopy (FTIR), Transmission electron microscope (TEM) and X-ray diffraction (XRD). The surface plasmon resonance (SPR) band found at 434 nm confirmed the reduction of AgNO3 to AgNPs. TEM micrographs revealed that AgNPs are irregular in shape with the size range from 15-65 nm. The functional groups responsible for bio-reduction of silver nitrate into silver were analyzed by FTIR and confirmed by X-ray photoelectron spectrum (XPS). Further these biogenic AgNP were evaluated for insecticidal activities against stored product pests, Tribolium castaneum (Flour beetle), Rhyzopertha dominica (F.)(Lesser grain borer) and Sitophilus oryzae L (Rice weevil). The fabricated AgNPs showed moderate activity on stored pests and strong antibacterial activity with varying degrees against Xanthomonas campestris and Ralstonia solanacearum as evidenced by their zone of inhibition at all concentrations. Hence, these AgNP can be used as control agents against agricultural pests and pathogens in future.

Plant-mediated synthesis of nanoparticles: A newer and safer tool against mosquito-borne diseases?

Prevention and control of mosquito-borne diseases is a key challenge of huge public health importance. Plant-mediated synthesis of nanoparticles has recently gained attention as a cheap, rapid and eco-friendly method to control mosquito vector populations, with special reference to young instars. Furthermore, plant-fabricated nanoparticles have been successfully employed as dengue virus growth inhibitors. In this Editorial, parasitologists, entomologists and researchers in drug nanosynthesis are encouraged to deal with a number of crucial challenges of public health importance.

Cytotoxic Effect on Cancerous Cell Lines by Biologically Synthesized Silver Nanoparticles

The biosynthesis of nanoparticles has been proposed as an environmental friendly and cost effective alternative to chemical and physical methods. Silver nanoparticles are biologically synthesized and characterized were used in the study. The invitro cytotoxic effect of biologically synthesized silver nanoparticles against MCF-7 cancer cell lines were assessed. The cytotoxic effects of the silver nanoparticles could significantly inhibited MCF-7 cancer cell lines proliferation in a time and concentration-dependent manner by MTT assay. Acridine orange, ethidium bromide (AO/EB) dual staining, caspase-3 and DNA fragmentation assays were carried out using various concentrations of silver nanoparticles ranging from 1 to 100 μg/mL. At 100 μg/mL concentration, the silver nanoparticles exhibited significant cytotoxic effects and the apoptotic features were confirmed through caspase-3 activation and DNA fragmentation assays. Western blot analysis has revealed that nanoparticle was able to induce cytochrome c release from the mitochondria, which was initiated by the inhibition of Bcl-2 and activation of Bax. Thus, the results of the present study indicate that biologically synthesized silver nanoparticles might be used to treat breast cancer. The present studies suggest that these nanoparticles could be a new potential adjuvant chemotherapeutic and chemo preventive agent against cytotoxic cells. However, it necessitates clinical studies to ascertain their potential as anticancer agents.

Biophysical Methods for the Elucidation of the S-Layer Proteins/Metal Interaction.

Surface-layers (S-layers) are macromolecular paracrystalline arrays of proteins or glycoproteins that can self-assemble into 2-dimensional semi-permeable meshworks to overlay the cell surface of many bacteria and archaea. They usually assemble into lattices with oblique, square or hexagonal symmetry and serve as an interface between the bacterial cell and the environment. Isolated S-layers can recrystallize into two-dimensional regular arrays in suspension or on various surfaces, thus being an appropriate material for several bionanotechnological purposes. Promising applications of S-layers include their use as biotemplates for the capture of metal ions or the synthesis of metal nanoclusters.

Nanoinformatics: an emerging area of information technology at the intersection of bioinformatics, computational chemistry and nanobiotechnology

After the progress made during the genomics era, bioinformatics was tasked with supporting the flow of information generated by nanobiotechnology efforts. This challenge requires adapting classical bioinformatic and computational chemistry tools to store, standardize, analyze, and visualize nanobiotechnological information. Thus, old and new bioinformatic and computational chemistry tools have been merged into a new sub-discipline: nanoinformatics. This review takes a second look at the development of this new and exciting area as seen from the perspective of the evolution of nanobiotechnology applied to the life sciences. The knowledge obtained at the nano-scale level implies answers to new questions and the development of new concepts in different fields. The rapid convergence of technologies around nanobiotechnologies has spun off collaborative networks and web platforms created for sharing and discussing the knowledge generated in nanobiotechnology. The implementation of new database schemes suitable for storage, processing and integrating physical, chemical, and biological properties of nanoparticles will be a key element in achieving the promises in this convergent field. In this work, we will review some applications of nanobiotechnology to life sciences in generating new requirements for diverse scientific fields, such as bioinformatics and computational chemistry.

Study on the development of nanotechnology in advanced countries and in Brazil: [review] / Estudo sobre o desenvolvimento da nanotecnologia nos países avançados e no Brasil: [revisão]

The study shows how nanotechnology evolves in developed countries and Brazil, raising aspects of private and governmental initiatives. The investigation was based in scientific literature, electronic articles and conference reports. Several sources of literature were used, including electronic databases and reference lists. By this study, it was observed that, although nanotechnology is in initial stage of development all over the world, the developed countries have had growing public and private investments in the area each year. In those countries, there is a concern toward both, the formation of specialists in nanotechnology and the transference of technology developed in universities and research institutes to industry. In Brazil, the study showed that despite the growing concern of investigators, national research centers and financial centers toward the development of the nanotechnology, there is still a need for more investment and formation of area specialists.

O presente trabalho faz um estudo sobre o desenvolvimento da nanotecnologia, com enfoque na área de saúde, em países tecnologicamente mais avançados e no Brasil, levantando aspectos de iniciativas governamentais e privadas. A investigação foi baseada em literatura científica, artigos eletrônicos e relatórios de conferências. Foi observado que, apesar da nanotecnologia estar em estágio inicial no mundo inteiro, os países tecnologicamente mais avançados têm tido investimentos crescentes na área a cada ano, tanto públicos quanto privados. Há grande preocupação nesses países quanto à formação de profissionais especialistas na área e à transferência da tecnologia desenvolvida por universidades e institutos de pesquisa para a indústria. No Brasil, o estudo mostrou que apesar da crescente preocupação dos pesquisadores, centros de pesquisa e centros de financiamento com o desenvolvimento da nanotecnologia, ainda há necessidade de maiores investimentos e formação de profissionais especialistas na área.