Alternative sources of fuel have been a concern in the last few decades. The growth of urbanization and industrialization will lead to the exhaustion of fossil fuels, attracting studies on alternative routes. The main aim of this study was to produce biodiesel from waste cooking oil (WCO) by methyl transesterification using sodium hydroxide as a catalyst. For this, the physicochemical parameters of biodiesel were studied in triplicate (density, acidity, saponification, viscosity, corrosiveness to copper, visual appearance, and cloud point). An analysis by thin layer chromatography and infrared spectrometry was also performed. The increase in yield (83.3%) was directly proportional to the increase in the catalyst (0.22 g of NaOH). The infrared absorption spectra of WCO and biodiesel showed the presence of common and singular bands of each material. Furthermore, a simple and low-cost mechanism was proposed for purifying glycerol. The spectra of glycerol versus purified glycerin showed that the glycerin produced was pure, being used in the formulation of bioplastic. The product was checked for biodegradation and photodegradation, with incredible soil-degradation times of 180 days and photodegradation of only 60 days. In this way, biodiesel production from WCO showed environmentally friendly proposals and applicability. As the next steps, it is necessary to test the biodiesel produced in combustion engines and improve the bioplastic production, including a spectroscopic characterization and extensive biodegradation testing.

The insertion of DNA into primary mammalian cells is an important step towards gene therapy and production of transgenic animals. Recently, carbon nanotubes have been explored as an efficient novel non-viral system for delivering genes to cells due to their unique structure and properties. However, their potential for transfecting primary bovine cells in non-toxic concentrations has not been tested. The purpose of this study was to evaluate the cytotoxicity of carboxylic acid-functionalized multiwalled carbon nanotubes (COOH-MWCNTs) and their use to deliver plasmid DNA encoding the gene of green fluorescent protein to bovine primary fibroblast cells. Flow-cytometry cell viability results have shown the non-toxic nature of COOH-MWCNTs at low concentrations. The frequency shifts in Raman spectroscopy showed that the plasmid DNA connects to the nanomaterial. Fluorescence imaging, flow-cytometry and PCR analysis confirmed that the COOH-MWCNT nanovectors delivered pDNA into primary fibroblast cells successfully. The results show that COOH-MWCNTs can be attractive alternatives for delivery of DNA into hard-to-transfect primary bovine cells.

In the food industry, packaging is used to protect food. However, traditional packaging has serious environmental impacts. Thus, studies have investigated packaging composed of biodegradable polymers. Accordingly, the present study aimed to obtain and characterize polymeric films of sodium alginate and polyethylene glycol crosslinked with tetraethoxysilane and doped with nano-zinc oxide or nano-silicon oxide and evaluate their cytotoxicity and bactericidal activity against coliforms and Escherichia coli. The nanoparticles and crosslinked materials were characterized using infrared and Raman spectroscopy. The cytotoxicity of the films was evaluated using a direct contact assay with a bovine fibroblast cell model. The bactericidal activity of the films was assessed by determining whether the contamination indicators were activated. The average sizes of the ZnO and SiO₂ nanoparticles were 408.3 and 125.3 nm, respectively, and their zeta potentials were −31.6 and −31.1 mV, respectively. Cell growth inhibition zone tests indicated that 75 ALG/25 PEG/SiO₂ was slightly toxic, while 25 ALG/75 PEG/ZnO exhibited mild toxicity. Cell area analysis showed that the addition of SiO₂ decreased the cytotoxicity of the obtained films. Finally, it was possible to observe the inactivation of both contamination bioindicators. Therefore, films containing nanoparticles could be promising biomaterials for packaging in the food industry. Graphical Abstract