Microcarrier-based cell culture systems have gained significant attention and popularity in tissue engineering and regenerative medicine. In this culture system, tissue cells are grown as a monolayer on the surface of small solid particles called microcarriers (100 to 300 μm), kept suspended in the culture medium by stirring. This technology has paved the way for creating engineered tissues, one of the cutting-edge topics in tissue engineering and regenerative medicine. Microcarrier-based approaches have been proposed for three-dimensional (3D) cell culture in which cellular morphology and functions are maintained in vivo. This paper provides an overview of the optimal characteristics such as microcarriers’ size, shape, density and porosity. Various methods of preparation of microcarriers and surface modification techniques have been elaborated. Recent advances and applications of microcarriers in biotechnology fields, like the production of viral vaccines and recombinant proteins, culture and expansion of stem cells (SC), are described.

In this study, waste cooking oil (WCO) with high free fatty acid (FFA) content was esterified to produce biodiesel, and the catalysts’ performance was investigated. Two deep eutectic solvents (DESs) were employed as the liquid catalysts (K2CO3-Gly and KOH-Gly), while the solid heterogeneous catalysts used were spent bleaching earth (SBE), KCC-1, and Na/KCC-1. DESs were prepared by mixing at reaction temperature and time of 80°C and 120 min, respectively. The American Standard Testing Method (ASTM) D974 determined the acid value. The catalysts were first screened for their catalytic activity in WCO esterification. The parameters investigated in this study were oil-to-methanol molar ratio, catalyst loading, reaction time, and temperature. The highest conversion (94.7%) was obtained using Na/KCC-1. The performance of solid and liquid catalysts was evaluated using KOH-Gly and SBE for the reduction of FFA in WCO under different conditions of oil-to-methanol molar ratio (1:6–1:10), catalysts loading (0.2–2.0 g), reaction time (30–60 min), and temperature (40–100°C). The highest reduction of FFA in the esterification process for KOH-Gly and SBE as catalysts was 97.74% and 84.2%, respectively. Transesterification of the esterified oil shows a promising result (97%), and the process can potentially be scaled up. The GC-MS result shows that the produced oil has the highest percentage of hexadecanoic acid and methyl ester.

This research explores the formulation of sustainable and high-performance greases utilizing waste transformer oil (WTO) as a base material and incorporating additives such as molybdenum disulphide (MoS2), polytetrafluoroethylene (PTFE), and fumed silica. The study involves a meticulous process, including the pre-treatment of WTO, grease production, blending of additives, and thorough characterization. Various tests, including consistency, dropping point, oil bleeding, and FTIR analysis, provide comprehensive insights into the thermal stability, mechanical properties, and molecular composition of the formulated greases. The research contributes to advancing grease formulation practices, with a focus on sustainability and performance enhancement. The successful integration of waste transformer oil and additives demonstrates the potential for environmentally conscious lubrication solutions. This study provides a valuable foundation for future developments in the field.