Author: Elsbeth Joan Evangelista
Evangelista, Elsbeth Joan, 2025 Optimizing plasma-assisted extraction of spirulina-derived bioactive compounds for wound healing applications, Flinders University, College of Medicine and Public Health
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Chronic wound infections remain an increasingly burdensome threat to public health, globally demanding innovative and novel therapeutic approaches. Spirulina maxima, a blue-green microalga rich in bioactive compounds including c-phycocyanin, antioxidant, and bioactive compounds including essential proteins, has exemplified wound healing potential. However, conventional extraction methods often limit recovery efficiency of these promising bioactive compounds due to their energy-intensive nature, which compromise the quality and reduces extraction yield leading to several scientific limitations. In this study, plasma-assisted extraction using dielectric barrier discharge (DBD) atmospheric plasma technology were utilized to optimize the yield and bioactive efficacy of S. maxima. The purpose of this study is to comprehensively determine the optimal processing parameters including voltage level (kV), treatment time (min), and NaCl concentration (g/L) for plasma-assisted extraction of S. maxima-derived bioactive compounds. Additionally, the study aims to evaluate the spectrum of antibacterial activity of the optimized plasma-treated S. maxima against a variety of clinically relevant Gram-positive and Gram-negative pathogens related to wound healing. To fine-tune the key parameters of plasma-assisted extraction, a Central Composite Design (CCD) was employed using Design Expert software. An optimized plasma condition setting of 3kV voltage, 7.42 minutes, 0.75 g/L NaCl concentration was identified to provide sufficient control causing to generate reactive oxygen and nitrogen species for effective cell wall disruption without any further degradation significantly enhanced c-phycocyanin (CPC) concentration compared to conventional freeze-thaw method and untreated S.maxima supernatant. The antioxidant capacity is evaluated using the DPPH radical scavenging assay, reveals a preserved capacity post-plasma treatment. Morphological analyses in SEM and epifluorescence analysis reveals that extensive plasma-induced cell way disruption after plasma exposure can directly correlate with improved bioactive compound release. Among all tested conditions, the optimized 3kV plasma treatment condition stands out enhancing the antibacterial capacity of plasma-treated S. maxima supernatant with a greater effect observed in Gram-positive bacteria, specifically Staphylococcus epidermidis, and a significant effectiveness against Staphylococcus aureus as confirmed by CFU enumeration, and flow cytometry assays. While a notable antibacterial capacity was observed in Gram-negative Pseudomonas aeruginosa, and a lower sensitivity was shown by Escherichia coli to the plasma-treated extract. Despite these current results, some limitation must be recognized and be addressed for future visions. By integrating innovative plasma-assisted technology, it contributes to microalgal technology by discovering a new innovative extraction technique that provides a promising strategy that may offer innovative solution for chronic wound applications.
Keywords: Plasma-assisted extraction, dielectric barrier discharge, Spirulina maxima, microalgae, bioactive compounds, c-phycocyanin, antioxidant activity, wound healing, chronic wounds, antimicrobial resistance, antibacterial assay, Gram-positive bacteria, Gram-negative bacteria, flow cytometry, central composite design, optimization, scanning electron microscopy, epifluorescence microscopy, hydrogel, protein extraction, DPPH assay, biomedical applications.
Subject: Biotechnology thesis
Thesis type: Masters
Completed: 2025
School: College of Medicine and Public Health
Supervisor: Dr. Andrew Hayles