Photo-activated proflavine degrades protein and impairs enzyme activity: Involvement of hydroxyl radicals

Test method for evaluating the photocytotoxic potential of fluorescence imaging products

Various fluorescence imaging agents are currently under clinical studies. Despite significant benefits, phototoxicity is a barrier to the clinical translation of fluorophores. Current regulatory guidelines on medication-based phototoxicity focus on skin effects during sun exposure. However, with systemic and local administration of fluorophores and targeted illumination, there is now possibility of photochemical damage to deeper tissues during intraoperative imaging procedures. Hence, independent knowledge regarding phototoxicity is required to facilitate the development of fluorescence imaging products. Previously, we studied a cell-free assay for initial screening of reactive molecular species generation from fluorophores. The current work addresses a safety test method based on cell viability as an adjunct and a comparator with the cell-free assay. Our goal is to modify and implement an approach based on the in vitro 3T3 neutral red uptake assay of the Organization for Economic Co-Operation and Development Test Guideline 432 (OECD TG432) to evaluate the photocytotoxicity of clinically relevant fluorophores. These included indocyanine green (ICG), proflavine, methylene blue (MB), and IRDye800, as well as control photosensitizers, benzoporphyrin derivative (BPD) and rose bengal (RB). We performed measurements at agent concentrations and illumination parameters used for clinic imaging. Our results aligned with prior studies, indicating photocytotoxicity in RB and BPD and an absence of reactivity for ICG and IRDye800. DNA interactive agents, proflavine and MB, exhibited drug/light dose-response curves like photosensitizers. This study provides evidence and insights into practices useful for testing the photochemical safety of fluorescence imaging products.

High-Affinity DNA Nanomatrix: A Platform Technology for Synergistic Drug Delivery and Photothermal Therapy

With the advent of nucleosome/nucleotide intercalating drugs, DNA-based nanocarriers have recently gained impetus. However, most of the newly proposed DNA nanosystems are rather complex, thereby having low scalability and translatability. In this study, we propose a simple DNA nanomatrix core encapsulated within a chitosan shell, which is expected to enhance the encapsulation efficiency of intercalating drugs. This has been demonstrated using proflavine hemisulfate (PfHS), a model intercalating agent that shows improved ROS generation, among other anticancerous properties. The release of the drug from the nanomatrix is triggered by providing a heat trigger using IR-792 perchlorate, a known NIR photothermal sensitizer.

Effects of spray drying, freeze drying, and vacuum drying on physicochemical and nutritional properties of protein peptide powder from salted duck egg white

Salted duck egg white contains many kinds of high quality protein, but it is often discarded as food factory waste because of high salinity and other reasons. The discarded salted duck egg white not only causes a waste of resources, but also causes environmental pollution. Using salted duck egg white as raw material, this study was completed to investigate the effects of three drying methods including freeze drying, vacuum drying, and spray drying on physicochemical and nutritional properties of protein powder from salted duck egg white. The results showed that the solubility, foaming and foaming stability, emulsification and emulsification stability of the protein peptide of salted duck egg white decreased to different degrees after drying. The scavenging rates of freeze-dried samples for superoxide anion, hydroxyl radical, and 1,1-Diphenyl-2-picrylhydrazyl (DPPH·) reached 48.76, 85.03, and 80.17%, respectively. Freeze drying had higher scavenging rates than vacuum drying and spray drying. The results of electron microscopy showed that freeze-drying had the least effect on the structure of protein peptide powder of salted duck egg white. The purpose of this experiment was to provide theoretical guidance and technical support for industrial drying of salted duck egg white protein solution.