Combined Gold Recovery and Nanoparticle Synthesis in Microbial Systems Using Fractional Factorial Design

The importance of factorial design on the optimization of biosensor performance: immobilization of glucose oxidase as a case study

Conventionally, the optimization of glucose biosensors is achieved by varying the concentrations of the individual reagents used to immobilize the enzyme. In this work, the effect and interaction between glucose oxidase enzyme (GOx), ferrocene methanol (Fc), and multi-walled carbon nanotubes (MWCNTs) at different concentrations were investigated by a design of experiments (DoE). For this analysis, a factorial design with three factors and two levels each was used with the software RStudio for statistical analysis. The data were obtained by electrochemical experiments on the immobilization of GOx-Fc/MWCNT at different concentrations. The results showed that the factorial DoE method was confirmed by the non-normality of the residuals and the outliers of the experiment. When examining the effects of the variables, analyzing the half-normal distribution and the effects and contrasts for GOx-Fc/MWCNT, the factors that showed the greatest influence on the electrochemical response were GOx, MWCNT, Fc, and MWCNT:Fc, and there is a high correlation between the factors GOx, MWCNT, Fc, and MWCNT:Fc, as shown by the analysis of homoscedasticity and multicollinearity. With these statistical analyses and experimental designs, it was possible to find the optimal conditions for different factors: 10 mM mL-1 GOx, 2 mg mL-1 Fc, and 15 mg mL-1 MWCNT show a greater amperometric response in the glucose oxidation. This work contributes to advancing enzyme immobilization strategies for glucose biosensor applications. Systematic investigation of DoE leads to optimized immobilization for GOx, enables better performance as a glucose biosensor, and allows the prediction of some outcomes.

Phyto-assisted synthesis of zinc oxide nanoparticles using Bauhinia variegata buds extract and evaluation of their multi-faceted biological potentials

Zinc oxide nanoparticles have wide range biological, biomedical and environmental applications. However, traditional nanofabrication of ZnONPs uses various toxic chemicals and organic solvents which limit their bio-applications. To overcome this hurdle, Bauhinia variegata derived buds extract was utilized to fabricate ZnONPs. The greenly generated ZnONPs were successfully prepared and extensively characterized using different analytical tools and the average crystalline size was calculated as 25.47 nm. Further, bioengineered ZnONPs were explored for multiple biological activities that revealed excellent therapeutic potentials. The antibacterial potential was determined using different bacterial strains. Pseudomonas aeruginosa (MIC: 137.5 µg/mL) was reported to be the most resistant variant while Bacillus subtilis (MIC: 34.38 µg/mL) was observed to be most susceptible bacterial strain. DPPH radical scavenging potential was measured to determine the antioxidant capacity of ZnONPs and the highest scavenging potential was observed as 82% at highest of 300 µg/mL. The fungicidal effect of green ZnONPs in comparison with Amphotericin B was assessed against five selected pathogenic fungal strains. The results revealed, Fusarium solani (MIC: 46.875 µg/mL) was least resistant and Aspergillus flavus (MIC: 187.5 µg/mL) was most resistant in fungicidal examination. Cytotoxicity potential of B.V@ZnONPs was analyzed against newly hatched nauplii of brine shrimps. The results for greenly produced ZnONPs was recorded as 39.78 µg/mL while 3.006 µg/mL was reported for positive control vincristine sulphate. The results confirmed the category of general cytotoxic for greenly synthesized nano sized B.V@ZnONPs.

A Uni-Micelle Approach for the Controlled Synthesis of Monodisperse Gold Nanocrystals

Small-size gold nanoparticles (AuNPs) are showing large potential in various fields, such as photothermal conversion, sensing, and medicine. However, current synthesis methods generally yield lower, resulting in a high cost. Here, we report a novel uni-micelle method for the controlled synthesis of monodisperse gold nanocrystals, in which there is only one kind micelle containing aqueous solution of reductant while the dual soluble Au (III) precursor is dissolved in oil phase. Our synthesis includes the reversible phase transfer of Au (III) and "uni-micelle" synthesis, employing a Au (III)-OA complex as an oil-soluble precursor. Size-controlled monodisperse AuNPs with a size of 4-11 nm are synthesized by tuning the size of the micelles, in which oleylamine (OA) is adsorbed on the shell of micelles and enhances the rigidity of the micelles, depressing micellar coalescence. Monodisperse AuNPs can be obtained through a one-time separation process with a higher yield of 61%. This method also offers a promising way for the controlled synthesis of small-size alloy nanoparticles and semiconductor heterojunction quantum dots.

Applications of Green Synthesized Metal Nanoparticles - a Review

Green nanotechnology is an emerging field of science that focuses on the production of nanoparticles by living cells through biological pathways. This topic plays an extremely imperative responsibility in various fields, including pharmaceuticals, nuclear energy, fuel and energy, electronics, and bioengineering. Biological processes by green synthesis tools are more suitable to develop nanoparticles ranging from 1 to 100 nm compared to other related methods, owing to their safety, eco-friendliness, non-toxicity, and cost-effectiveness. In particular, the metal nanoparticles are synthesized by top-down and bottom-up approaches through various techniques like physical, chemical, and biological methods. Their characterization is very vital and the confirmation of nanoparticle traits is done by various instrumentation analyses such as UV-Vis spectrophotometry (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), atomic force microscopy (AFM), annular dark-field imaging (HAADF), and intracranial pressure (ICP). In this review, we provide especially information on green synthesized metal nanoparticles, which are helpful to improve biomedical and environmental applications. In particular, the methods and conditions of plant-based synthesis, characterization techniques, and applications of green silver, gold, iron, selenium, and copper nanoparticles are overviewed.

Green Synthesis of Silver Nanoparticles Loaded Hydrogel for Wound Healing; Systematic Review

Wound healing is a biological process that involves a series of consecutive process, and its impairment can lead to chronic wounds and various complications. Recently, there has been a growing interest in employing nanotechnology to enhance wound healing. Silver nanoparticles (AgNPs) have expanded significant attention due to their wide range of applications in the medical field. The advantages of AgNPs include their easy synthesis, change their shape, and high surface area. Silver nanoparticles are very efficient for topical drug administration and wound healing because of their high ratio of surface area to volume. The efficiency of AgNPs depends on the synthesis method and the intended application. Green synthesis methods offer an eco-friendly approach by utilizing natural sources such as plant extracts and fungus. The characterization of nanoparticles plays an important character, and it is accomplished through the use of several characterization methods such as UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). These techniques are employed to confirm the specific characters of the prepared Silver Nanoparticles. Additionally, the review addresses the challenges and future perspectives of utilizing green-synthesized AgNPs loaded in Polyacrylamide hydrogel for wound healing applications, including the optimization of nanoparticle size, and release kinetics. Overall, this review highlights the potential of green-synthesized AgNPs loaded in Polyacrylamide hydrogel as promising for advanced wound healing therapies. There are different approaches of usage of AgNPs for wound healing such as polyacrylamide -hydrogels, and the mechanism after their antibacterial action, have been exposed.