Nanoscience & Nanotechnology-Asia - Volume 11, Issue 5, 2021

Mercury (Hg) contamination is a problem that currently affects not only the environment but also human health. Various types of commercial adsorbents have been proposed for its removal. Silver is a noble element that can chemically adsorb mercury, forming amalgams. However, its use as an adsorbent presents the following disadvantages: rapid surface saturation and high cost. These limitations can easily be overcome using silver nanoparticles (AgNPs). With a size of less than 100 nm, their reactivity, their high surface area, and a minimal amount of metallic precursor, they are ideal candidates for mercury removal. This study presents a compendium of the use of conventional mercury adsorbents and the use of AgNPs for their colorimetric detection and removal in different matrices, in both the aqueous and gas phases of Hg⁰ and Hg²⁺. In addition, the number of patents available in each case is analyzed. AgNPs as colorimetric sensors allow quick detection of mercury in-situ. Additionally, the adsorption systems formed with AgNPs, allow obtaining stable and chemically inert complexes, facilitating their recycling. It is concluded that the use of AgNPs is particularly efficient for the detection and removal of mercury, presenting a removal percentage of over 90%. As a result of the patents analyzed, its use is perfectly applicable at an industrial level.

Background: Natural and synthetic polymeric materials can be used in the fields of biomedicine and pharmaceuticals as a material for controlled drug delivery. Among the synthetic polymers, polyesters are synthesized from two natural monomers: lactic and glycolic acid, which are biocompatible and biodegradable. Objective: Here, we review broad aspects of polyesters including its properties, synthesis, characterization, and particle drug delivery applications. Conclusion: Finally, we have concluded that polyesters are certainly very versatile material that are continuously reinvented for future application in new areas of science and medicine. However, several aspects must be considered when synthesizing polyesters, which have a direct influence on biodegradability and biocompatibility. These properties may limit the performance of in vitro and in vivo tests.

The application of nanotechnology to stem cell research and development has made great strides during the last years. Nanotechnology offers a new opportunity for the research and development of stem cells. The mammary gland is a dynamic organ that undergoes extensive morphogenesis during the different stages of embryonic development, puberty, pregnancy, lactation and involution. There are multipotent stem cells that reside in mammary tissue (MaSCs) with the ability to self-renew and even differentiate into all types of mammary cells. To identify, characterize, and differentiate MaSCs, a variety of methods have been used to understand the signal transduction pathways that promote their self-renewal and their cellular fate. In the last decade, stem cell therapy has become a promising and modern topic of scientific research, which has raised great expectations. However, by itself, it presents some problems that have been overcome with the use of nanoparticles (NPs). A triple function has been accomplished: transport of drugs or biomolecules that help in the differentiation and proliferation of stem cells, cell targeting and contrast agents for real-time monitoring and obtaining bioimages for diagnostic and detection systems. The main objective of applying stem cells in conjunction with NPs is to control cellular activity, mainly the regenerative capacity of mammary tissue against diseases such as mastitis or to optimize milk production. In this review, we provide a current overview of the application of nanomaterials on stem cells, specifically bovine stem cells in both the mammary gland and milk, as they are a potential source of cell progenitors with potential characteristics and could be used in potential therapies based on these cells.

Plant extracts contain secondary metabolites which have the potential to act as reducing and stabilizing agents contributing to a greener and more efficient method to synthesize nanoparticles. Rapid growth of Nanotechnology has led to an increased demand in various fields. This review summarizes the use of potent medicinal plant extracts to synthesize metal nanoparticles, methods employed to characterize the properties of the nanoparticles and its application. Characterization of the nanoparticle based on its shape, size, chemical bonds, surface properties, hydrodynamic diameter and crystalline structure using techniques such as UV-Visible Spectroscopy, XRD (X-ray Diffraction), TEM (Transmission Electron Microscopy), SEM (Scanning Electron Microscopy), EDS (X-ray energy dispersive spectroscopy), DLS (Dynamic Light Scattering), Zeta Potential and FTIR (Fourier Transform-Infrared Spectroscopy) are elaborated. The synthesized metal nanoparticles have wide ranges of applications such as antimicrobial activity, antioxidative capability, anticancer effect, antidiabetic properties, plant growth enhancement, dye degradation effects and anti-larval properties. Recent advances in nanotechnology with special emphasis on plant metabolites provide an insight into their usage as plant-derived edible nanoparticles (PDNPs). Applications, limitations and future prospects of this technology have also been briefly discussed.

Background: Waste biomass derived reusable heterogeneous acid based catalysts are more suitable to overcome the problems associated with homogeneous catalysts. The use of agricultural biomass as catalyst for transesterification process is more economical and it reduces the overall production cost of biodiesel. The identification of an appropriate suitable catalyst for effective transesterification will be a landmark in the biofuel sector. Objective: In the present investigation, waste wood biomass was used to prepare a low cost sulfonated solid acid catalyst for the production of biodiesel using waste cooking oil. Methods: The pretreated wood biomass was first calcined then sulfonated with H2SO4. The catalyst was characterized by various analyses such as Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-ray diffraction (XRD). The central composite design (CCD) based response surface methodology (RSM) was applied to study the influence of individual process variables such as temperature, catalyst load, methanol to oil molar ration and reaction time on biodiesel yield. Results: The obtained optimized conditions are as follows: temperature (165°C), catalyst loading (1.625 wt%), methanol to oil molar ratio (15:1) and reaction time (143 min) with a maximum biodiesel yield of 95%. The Gas chromatography-mass spectrometry (GC-MS) analysis of biodiesel produced from waste cooking oil showed that it has a mixture of both monounsaturated and saturated methyl esters. Conclusion: Thus the waste wood biomass-derived heterogeneous catalyst for the transesterification process of waste cooking oil can be applied for sustainable biodiesel production by adding an additional value for the waste materials and also eliminating the disposable problem of waste oils.

Background: Lornoxicam is widely used for its anti-inflammatory, analgesic and antipyretic properties. However, it suffers from the limitations of possessing a relatively short elimination half-life ranging from 3 to 5 h, thereby; leading to repeated dosing which in turn may cause local irritation and ulceration. In addition, LXM also exhibits pH-dependent solubility. Effective management of inflammation in diseases such as arthritis requires the formulation of delivery systems that may be able to provide immediate release of drug for instant relief which shall be maintained for a prolonged period. Objective: The present research work was aimed to modify the release pattern of poorly water-soluble drug Lornoxicam by designing a biphasic tablet comprising of solid dispersion (immediate release form) and microspheres (controlled release form) for the effective management of inflammation. Methods: The solid dispersion (SD) was prepared by melting method using PEG 4000 and tween 80 and formation was confirmed by Differential Scanning Calorimetry (DSC) and Powder X-ray Diffraction (PXRD) studies. Polymeric microspheres loaded with Lornoxicam were prepared by ‘Emulsion Solvent-Evaporation’ method using Eudragit S-100 and Eudragit L-100. Microspheres (MS) were evaluated for drug entrapment efficiency, drug loading, drug content, particle size and in vitro release behaviour. Optimized microspheres (polymer concentration 0.5% w/v and drug concentration 0.1% w/v and solid dispersion (drug: PEG 4000: 4:6) were compressed in the ratio of 1:3 to produce biphasic tablet. The prepared tablets were evaluated for various pre-compression and post-compression parameters. Anti-inflammatory activity of the F4, M6 and the combination of SD and Microspheres in a ratio of 1:3 was carried out by Carrageenan induced paw edema method in Wistar rats. Results: The solid dispersions prepared by melting technique showed an enhanced dissolution rate as compared to the pure drug. LXM microspheres exhibited a sustained drug release. In vitro release of lornoxicam from biphasic tablets showed that 20% of the drug released at the end of first one hour, followed by 33% release at the end of 4^th h and maximum release of 94.1% at the end of 10 h. The prolonged effect continued till the end of 12 h. Results showed that the mixture of MS + SD exhibited 48% inhibition in 30 min which is increased to 88.63% at the end of 4 h which can be explained by initial burst release from the soluble layer of SD (which gave initial required effective concentration of Lornoxicam) followed by sustained release from matrix of microspheres (which maintained required level of Lornoxicam in blood). Conclusion: A successful modification of the release pattern of LXM was achieved by designing a biphasic tablet comprising of solid dispersion for the effective management of inflammation.

Background: Novel eco-friendly silver nanocomposites of xanthan/chitosan biguanidine hydrochloride polyelectrolyte complexes were successfully prepared. Methods: Silver nanoparticles (AgNPs) were formed through an insitu eco-friendly reduction by the non-toxic polysaccharides without the usage of toxic reagents. FTIR confirmed the successful preparation of the nanocomposites while XRD confirmed the presence of AgNPs with face-centered cubic structures. TEM confirmed the homogeneous distribution of AgNPs with an average size of 14.1 nm. SEM was used to study the surface morphology of the nanocomposites while the energy-dispersive X-ray spectroscopy (EDX) confirmed the presence of AgNPs. Results: Thermogravimetric analysis showed that the thermal stability was improved in the presence of AgNPs as detected from the calculated integral procedure decomposition temperature. Antibacterial activity against different bacteria species was significantly improved upon increasing the content of AgNPs. Conclusion: Due to their interesting properties, the prepared polyelectrolyte complexes and their AgNPs nanocomposites could be employed potentially in many biomedical applications like drug delivery.