Microalgae as a potential natural source for the green synthesis of nanoparticles

The increasing global population is driving the development of alternative sources of food and energy, as well as better or new alternatives for health and environmental care, which represent key challenges in the field of biotechnology. Microalgae represent a very important source material to produce several high-value-added bioproducts. Due to the rapid changes in the modern world, there is a need to build new materials for use, including those in the nanometer size, although these developments may be chronological but often do not occur at a time. In the last few years, a new frontier has opened up at the interface of biotechnology and nanotechnology. This new frontier could help microalgae-based nanomaterials to possess new functions and abilities. Processes for the green synthesis of nanomaterials are being investigated, and the availability of biological resources such as microalgae is continuously being examined. The present review provides a concise overview of the recent advances in the synthesis, characterization, and applications of nanoparticles formed using a wide range of microalgae-based biosynthesis processes. Highlighting their innovative and sustainable potential in current research, our study contributes towards the in-depth understanding and provides latest updates on the alternatives offered by microalgae in the synthesis of nanomaterials.

A domestic pressure cooker mediated, facile autoclaving method for the synthesis of silver nanoparticles

As an alternative to an expensive hydrothermal reactor, in the current method a domestic pressure was used for the synthesis of silver nanoparticles (Ag NP) using tree gum, kondagogu as dual functional reductant and stabilizer by autoclaving. The formation of Ag NP was evaluated with colour transformation, UV-Visible spectroscopy (UV-Vis) and transmission electron microscopy. The formation of Ag NP by gum confirmed from the developed yellow coloration of the solution and the appearance of surface plasmon resonance peak at 408 nm in the UV-Vis. The produced NP were spherical, polydisperse, particle size ranged from 2.9-17.6 nm and the average particle size was 4.5 ± 3.1 nm. The developed method is useful for demonstration, gaining hands on experience and production of metal and metal oxide NP in resource limited small laboratories, rural colleges, startups etc.•Pressure cooker serves as an easily accessible, durable, inexpensive, electricity independent hydrothermal nanoparticle production vessel.•Autoclaving serves as a facile, ecofriendly, less energy consuming, one pot, green method with dual functional role of in situ nanoparticle synthesis and sterilization.•Production of intrinsically safe and sterile nanoparticles amenable for in vivo and in vitro biomedical applications.

Mechanism study of silver nanoparticle production using Neurospora intermedia

Elucidation of the molecular mechanism of silver nanoparticle (AgNP) synthesis is necessary to control nanoparticle size, shape, and monodispersity. In this study, the mechanism of AgNP formation by Neurospora intermedia was investigated. The higher production rate of AgNP formation using a culture supernatant heat-treated at 100° and 121°C relative to that with an un-treated culture supernatant indicated that the native form of the molecular species is not essential. The effect of the protein molecular weight (MW) on the nanoparticle size distribution and average size was studied by means of ultraviolet-visible spectroscopy and dynamic light scattering. Using un-treated and concentrated cell-free filtrate passed through 10 and 20 kDa cut-off filters led to the production of AgNPs with average sizes of 25, 30, and 34 nm, respectively. Also, using the permeate fraction of cell-free filtrate passed through a 100 kDa cut-off filter led to the formation of the smallest nanoparticles with the narrowest size distribution (average size of 16 nm and polydispersity index of 0.18). Sodium dodecyl sulphate polyacrylamide gel electrophoresis analysis of the fungal extracellular proteins showed two notable bands with the MWs of 15 and 23 kDa that are involved in the reduction and stabilisation of the nanoparticles, respectively.