Salt-Assisted High-Hydrostatic-Pressure Strategy to Achieve High-Efficiency Nondestructive Bacterial Inactivation for...

Collagen and its derivatives stand out as valuable biomaterials for applications in foods, cosmetics, healthcare products, medical equipment, and drug delivery carriers due to their high biocompatibility, biodegradability, and lack of toxicity and immunogenicity. However, the problem of microbial contamination in collagen is too important to ignore, which limits its further application in various fields. Traditional bacterial inactivation methods such as heating and irradiation can effectively kill microorganisms in solid collagen, yet struggle to eliminate microbes in liquid collagen while preserving its biological activity. How to completely eradicate microorganisms in liquid collagen without loss of collagen bioactivity, namely, nondestructive bacterial inactivation, has become a key scientific challenge in the field of biomaterials. To answer this challenge, this study attempts to develop a bacterial inactivation strategy based on high hydrostatic pressure (HHP) technology to achieve nondestructive bacterial inactivation of Escherichia coli (E. coli)-contaminated liquid collagen. Although HHP treatment alone cannot inactivate E. coli, its bacterial inactivation efficacy can be enhanced by appropriately adjusting the environmental parameters of liquid collagen. The obtained experimental results showed that E. coli, incubated in a 0.9-3.0% sodium chloride solution for 6 to 12 h and followed by HHP treatment at 300 MPa, could be eliminated, which indicates the great potential of salt-assisted HHP for bacterial inactivation. Meanwhile, the triple-helical structure of liquid collagen, characterized by circular dichroism (CD) spectroscopy and differential scanning calorimetry (DSC), could be preserved under the same HHP treatment conditions. Finally, the nondestructive bacterial inactivation effect of salt-assisted HHP was also observed in an E. coli-contaminated liquid collagen model. We hope that this work provides a feasible strategy to achieve high-efficiency, nondestructive bacterial inactivation for liquid collagen.