Chitosan is increasingly utilized in combination with melatonin in novel formulations for a wide range of therapeutic applications. As a biocompatible and biodegradable polymer, chitosan exhibits notable properties, including antioxidant, antimicrobial, moisturizing, and absorption capabilities, in addition to a high potential for chemical modification due to its functional groups. These characteristics make it a valuable material in biomedical, pharmaceutical, cosmetic, food packaging, and environmental applications. Melatonin, an indoleamine primarily synthesized in the pineal gland but also found in various peripheral organs and in diverse organisms—including plants, bacteria, and fungi—has been extensively investigated for its antioxidant, anti-apoptotic, and anti-inflammatory activities, as well as its roles in immunomodulation, mitochondrial function, and melanin biosynthesis. This review summarizes recent advances in the combined use of chitosan and melatonin, with emphasis on their synergistic effects in wound healing, anti-cancer therapies, tissue engineering (i.e., skin and bone regeneration), and drug delivery systems. Additional potential applications are discussed in the context of cosmetology, aesthetic medicine, and veterinary practice.

Background and Objectives: This study evaluated the effectiveness of a pocket‐sized ultrasound device in preoperative planning for lymphaticovenular anastomosis (LVA) to enhance lymphedema treatment outcomes.Methods: A retrospective analysis was performed on 24 patients who underwent LVA for secondary upper extremity lymphedema between June 2020 and August 2022. Patients were categorized into two groups: the ultrasound group, which used a pocket‐sized device (Vscan Air), for preoperative vein identification, and a control group that did not. Preoperative lymphatic mapping was performed using indocyanine green lymphography, and suitable veins for anastomosis were identified using ultrasound. Upper extremity lymphedema index and incision length were compared.Results: Participants in the ultrasound group had a shorter average incision length (2.85 ± 0.48 cm) than those in the control group (3.23 ± 0.78 cm, p = 0.038), indicating a more targeted and minimally invasive approach. Although volume reduction rates were not significantly different, the pocket ultrasound device facilitated more precise vein selection, enhancing surgical planning.Conclusion: Pocket‐sized ultrasound devices provide a cost‐effective and practical solution for vein identification during LVA, particularly in resource‐limited settings. While high‐frequency ultrasound offers superior resolution, portable devices could become standard tools for lymphatic surgery with continued technological advancement.

Melatonin (N-acetyl-5-methoxytryptamine) is an evolutionarily conserved indoleamine with potent antioxidant and cytoprotective properties. Due to its amphiphilic nature, melatonin readily accumulates in mitochondria, where it regulates redox homeostasis and bioenergetic function. Although melatonin has been implicated in cutaneous protection against ultraviolet radiation (UVR), the mitochondrial mechanisms underlying its effects in UVB-exposed keratinocytes remain insufficiently characterized. In this study, we investigated the mitochondrial-centered protective effects of melatonin in human epidermal keratinocytes (NHEKs) subjected to UVB irradiation. UVB exposure induced a dose-dependent decrease in cell viability and proliferation, accompanied by excessive reactive oxygen species (ROS) production, mitochondrial membrane depolarization (ΔΨm), ATP depletion, caspase-3 activation, and increased expression of DNA damage- and senescence-associated markers, including γH2AX, p53, and p16^INK4a. Pre-treatment with melatonin attenuated these alterations by reducing oxidative stress, preserving ΔΨm, maintaining ATP production, suppressing apoptotic signaling, and modulating DNA damage- and senescence-related pathways. Collectively, our findings suggest that mitochondria are a central target of melatonin in UVB-exposed keratinocytes and demonstrate that maintenance of mitochondrial redox balance and bioenergetic integrity is associated with reduced apoptotic and senescence-related changes.