Engineering extracellular vesicles for diagnosis and therapy.

Extracellular vesicle (EV)-based therapeutics have gained substantial interest in the areas of drug delivery, immunotherapy, and regenerative medicine. However, the clinical translation of EVs has been slowed due to limited yields and functional heterogeneity, as well as inadequate targeting. Engineering EVs to modify their inherent function and endow them with additional functions has the potential to advance the clinical translation of EV applications. Bio-orthogonal click chemistry is an engineering approach that modifies EVs in a controlled, specific, and targeted way without compromising their intrinsic structure. Here, we provide an overview of bio-orthogonal labeling approaches involved in EV engineering. We also present the isolation methods of bio-orthogonally labeled vesicles using magnetic beads, microfluidics, and microarray chip technologies. We highlight the in vivo applications of bio-orthogonal labeling EVs for diagnosis and therapy, especially the exciting potential of bio-orthogonal glycometabolic engineered EVs for targeted therapies.

The bioproduction of astaxanthin: A comprehensive review on the microbial synthesis and downstream extraction.

Astaxanthin is a valuable orange-red carotenoid with wide applications in agriculture, food, cosmetics, pharmaceuticals and nutraceuticals areas. At present, the biological synthesis of astaxanthin mainly relies on Haematococcus pluvialis and Xanthophyllomyces dendrorhous. With the rapid development of synthetic biology, more recombinant microbial hosts have been genetically constructed for astaxanthin production including Escherichia coli, Saccharomyces cerevisiae and Yarrowia lipolytica. As multiple genes (15) were involved in the astaxanthin synthesis, it is particularly important to adopt different strategies to balance the metabolic flow towards the astaxanthin synthesis. Furthermore, astaxanthin is a fat-soluble compound stored intracellularly, hence efficient extraction methods are also essential for the economical production of astaxanthin. Several efficient and green extraction methods of astaxanthin have been reported in recent years, including the superfluid extraction, ionic liquid extraction and microwave-assisted extraction. Accordingly, this review will comprehensively introduce the advances on the astaxanthin production and extraction by using different microbial hosts and strategies to improve the astaxanthin synthesis and extraction efficiency.