Development of a custom biological scaffold for investigating ultrasound-mediated intracellular delivery

Intracellular protein delivery: New insights into the therapeutic applications and emerging technologies

The inability to cross the plasma membranes traditionally limited the therapeutic use of recombinant proteins. However, in the last two decades, novel technologies made delivering proteins inside the cells possible. This allowed researchers to unlock intracellular targets, once considered 'undruggable', bringing a new research area to emerge. Protein transfection systems display a large potential in a plethora of applications. However, their modality of action is often unclear, and cytotoxic effects are elevated, whereas experimental conditions to increase transfection efficacy and cell viability still need to be identified. Furthermore, technical complexity often limits in vivo experimentation, while challenging industrial and clinical translation. This review highlights the applications of protein transfection technologies, and then critically discuss the current methodologies and their limitations. Physical membrane perforation systems are compared to systems exploiting cellular endocytosis. Research evidence of the existence of either extracellular vesicles (EVs) or cell-penetrating peptides (CPPs)- based systems, that circumvent the endosomal systems is critically analysed. Commercial systems, novel solid-phase reverse protein transfection systems, and engineered living intracellular bacteria-based mechanisms are finally described. This review ultimately aims at finding new methodologies and possible applications of protein transfection systems, while helping the development of an evidence-based research approach.

Effects of salt concentration on the structure and properties of composite fiber of carboxymethyl cellulose/N-2-hydroxylpropyl trimethyl ammonium chloride chitosan prepared by polyelectoyte complexation-freeze drying

The conventional electrospinning process for the preparation of fibers usually require complex equipment and complicated preparation processes, as well as chemical crosslinkers and organic solvents, which limits its application in the preparation of biomedical materials. In the current study, carboxymethyl cellulose/N-2-hydroxylpropyl trimethyl ammonium chloride chitosan (CMC/HACC) composite fibers were fabricated by polyelectrolyte complexation (PEC) and freeze drying coupled method in both pure water and NaCl solution. The structures of the as-prepared fibers and the effects of NaCl concentration on the structures of fibers were studied by FTIR, solid ¹³C NMR, XRD, XPS and SEM. The formation mechanism of the composite fiber and the effects of NaCl concentration on structure and properties of the composite fiber were simulated in the Materials Studio software and discussed. The swelling properties and the thermal decomposition kinetics of the composite fiber were studied. The results suggest that the addition of NaCl electrolyte to the complexing system significantly affects the structure and properties of the PEC fiber. Our work has provided a new preparation route to the composite fibers of natural polymers with controllable structures and properties by the combination of PEC and freeze drying techniques using NaCl with desired concentration as the electrolyte.

Ultrasonic irradiation of low intensity with a mode of sweeping frequency enhances the membrane permeability and cell growth rate of Candida tropicalis

Here we report the enhancement of both cellular permeability and cell growth rate of Candida tropicalis after treatment with the ultrasonic irradiation of low intensity using a mode of sweeping frequency (UILS) generated by a self-developed ultrasonic device in our lab. After the ultrasonic treatment, remarkable biomass enhancement of the yeast was observed; the hyphae became significantly longer; the seeped cellular protein and nucleic acid from the yeast increased and the cellular Ca²⁺ content became lower. Illumina transcriptome sequencing showed that the ultrasonic treatment affected the expression of genes involved in diverse cellular components, biological processes and molecular functions. RT-PCR and Western blotting further confirmed the up-/down-regulation of genes in the ultrasound-treated yeasts. The optimal conditions of the ultrasonic treatment for the maximum biomass addition were determined as follows: the yeast was treated for 1h at the mid logarithmic phase, the frequency was 28±2kHz and the power density was 120W/L. Under these conditions, the Candida tropicalis biomass increased by 142.5% compared with the untreated yeast.