Phycocyanin is a blue colored pigment, synthesized by several species of cyanobacteria and red algae. Besides the application as a food-colorant, the pigmented protein is of high interest as a pharmaceutically and nutritionally valuable compound. Since cyanobacteria-derived phycocyanin is thermolabile, red algae that are adapted to high temperatures are an interesting source for phycocyanin extraction. Still, the extraction of high quality phycocyanin from red algae is challenging due to the strong and rigid cell wall. Since standard techniques show low yields, alternative methods are needed. Recently, spark discharges have been shown to gently disintegrate microalgae and thereby enable the efficient extraction of susceptible proteins. In this study, the applicability of spark discharges for phycocyanin extraction from the red alga Cyanidium caldarium was investigated. The efficiency of 30 min spark discharges was compared with standard treatment protocols, such as three times repeated freeze-thaw cycles, sonication, and pulsed electric fields. Input energy for all physical methods were kept constant at 11,880 J to ensure comparability. The obtained extracts were evaluated by photometric and fluorescent spectroscopy. Highest extraction yields were achieved with sonication (53 mg/g dry weight (dw)) and disintegration by spark discharges (4 mg/g dw) while neither freeze-thawing nor pulsed electric field disintegration proved effective. The protein analysis via LC-MS of the former two extracts revealed a comparable composition of phycobiliproteins. Despite the lower total concentration of phycocyanin after application of spark discharges, the purity in the raw extract was higher in comparison to the extract attained by sonication.

Peroxynitrite (ONOO⁻) and peroxynitrous acid (ONOOH) are known as short acting reactive species with nitrating and oxidative properties, which are associated with their antimicrobial effect. However, to the best of our knowledge, ONOOH/ONOO^- are not yet used as antimicrobial actives in practical applications. The aim is to elucidate if ONOOH generated in situ from acidified hydrogen peroxide (H₂O₂) and sodium nitrite (NaNO₂) may serve as an antimicrobial active in disinfectants. Therefore, the dose-response relationship and mutagenicity are investigated. Antimicrobial efficacy was investigated by suspension tests and mutagenicity by the Ames test. Tests were conducted with E. coli. For investigating the dose-response relationship, pH values and concentrations of H₂O₂ and NaNO₂ were varied. The antimicrobial efficacy is correlated to the dose of ONOOH, which is determined by numerical computations. The relationship can be described by the efficacy parameter W, corresponding to the amount of educts consumed during exposure time. Sufficient inactivation was observed whenever W ≥ 1 mM, yielding a criterion for inactivation of E. coli by acidified H₂O₂ and NaNO₂. No mutagenicity of ONOOH was noticed. While further investigations are necessary, results indicate that safe and effective usage of ONOOH generated from acidified H₂O₂ and NaNO₂ as a novel active in disinfectants is conceivable.

Wound healing is an important and still-challenging task in modern medicine. In particular, therapeutic options for treating chronic wounds linked to diseases like diabetes are limited. One promising approach is the application of cold atmospheric plasma (CAP) via medical plasma jets (PJs) or dielectric barrier discharges to specifically stimulate the healing process of non-healing wounds. However, limitations occur regarding the treatment area in the case of PJs. Thus, an innovative PJ array system (PJAS) was developed to extend the capabilities of established PJs in treating large areas like chronic wounds. Utilizing patented gas switching technology, the PJAS aims to provide effective treatment over larger areas within shorter application times. Determination of performance and safety indicators included measurements of leakage current, temperature, starch–potassium iodide tests, suspension tests, cell viability tests and inhibition zone assays. Values are compared with a medical PJ system, the kINPen^® MED. Findings indicated that the PJAS showed enhanced efficacy compared to present medical PJs. Systematic analyses of leakage current, neutral gas temperature, and emission spectra confirmed the device’s safety. A two-step observation was found in the effluent temperature profile of the PJAS with a possible relation to free jet physics and argon-enriched zones. Starch–potassium iodide experiments revealed that the PJAS system oxidizes an area up to twice the size treated by the PJ under the same conditions. Antimicrobial suspension tests indicated an inactivation ranging from 2.1 to 4.9 orders of magnitude, while inhibition zone assays resulted in an up to 14-fold increase in the effective area for S. aureus and to a twofold increase for C. albicans in direct comparison to PJ. Additionally, treatment of human fibroblast cells indicated preserved cell vitality for 30 s of plasma exposure. Overall, the PJAS has the potential to become a promising therapeutic option for chronic wound treatment.