Abstract

Introduction: Wound infections negatively impact the healing process, and most chronic wounds are colonized by bacterial biofilms (1). Buddleja globosa Hope (BG) extracts have been traditionally used to treat skin wounds for their healing, anti-inflammatory, and antimicrobial properties (2). Scaffolds have been shown to promote cell proliferation and healing (3,4) and could be used to deliver bioactive compounds. However, the development of scaffolds rarely describes a rational design to optimize their therapeutic properties (5). This work aimed to develop an optimized scaffold with BG extract by Design of Experiment (DoE) to prevent and treat wound infections. Methods: First, 13 scaffold prototypes were prepared with variable %chitosan, %hyaluronic acid, and % gelatin (variables of the DoE) and fixed BG extract by lyophilization using a Box-Behnken design (BBD) (6). Bacterial adhesion, viability, and viability of mature biofilms were tested against biofilms Pseudomonas aeruginosa and Staphylococcus aureus in vitro. Compatibility was studied with human fibroblasts. Finally, 4 scaffolds with variable %BG extract and fixed polymeric content were developed and tested on bacterial adhesion, viability and in a mature dual-specie biofilm model. Results: The BBD methodology showed that %chitosan correlated with the reduced viability of S. aureus (R2= 0.98; p=0.0012) and reduced adhesion of P. aeruginosa (R2= 0.93; p=0.0195). Compatibility with fibroblasts correlated with %gelatin (R2= 0.96; p=0.0064). Optimized scaffolds with BG extract significantly reduced bacterial adhesion and viability, and reduced the viability of mature dual-specie biofilms (p=0.0181). Discussion: To our knowledge, this is the first report on the use of a DoE methodology to optimize the biological properties of scaffolds (5). Scaffolds made of these polymers should balance their chitosan and gelatin content to potentiate the antimicrobial properties without compromising biocompatibility (7). Reduction of bacterial adhesion (or anti-biofilm activity) was the most significant result. Therefore, these BG-loaded scaffolds have a promising therapeutic use to prevent bacterial infections and biofilm colonization of chronic wounds. An in vivo study in an infected wound model is currently ongoing. Funding: FONDECYT Research Initiation Project 11190348 (2019) and PAI 77190010 (2019).