Chitosan (CS) is a well-known stabilizer for metal nanoparticles in biomedical engineering. However, very few studies have explored other important roles of CS including reducing, shape-directing, and size-controlling. This review aims to provide the latest and most comprehensive overview of the roles of CS in the green synthesis of metal nanoparticles for biomedical applications. To the best of our knowledge, this is the first review that highlights these potentialities of CS. At first, a brief overview of the properties and the bioactivity of CS is presented. Next, the benefits of CS for enhancing the physicochemical behaviors of metal nanoparticles are discussed in detail. The representative biomedical applications of CS-metal nanoparticles are also given. Lastly, the review outlines the perceptual vision for the future development of CS-metal nanoparticles in the biomedicine field.

Monitoring the vital signs and physiological responses of the human body in daily activities is particularly useful for the early diagnosis and prevention of cardiovascular diseases. Here, we proposed a wireless and flexible biosensor patch for continuous and longitudinal monitoring of different physiological signals, including body temperature, blood pressure (BP), and electrocardiography. Moreover, these modalities for tracking body movement and GPS locations for emergency rescue have been included in biosensor devices. We optimized the flexible patch design with high mechanical stretchability and compatibility that can provide reliable and long-term attachment to the curved skin surface. Regarding smart healthcare applications, this research presents an Internet of Things-connected healthcare platform consisting of a smartphone application, website service, database server, and mobile gateway. The IoT platform has the potential to reduce the demand for medical resources and enhance the quality of healthcare services. To further address the advances in non-invasive continuous BP monitoring, an optimized deep learning architecture with one-channel electrocardiogram signals is introduced. The performance of the BP estimation model was verified using an independent dataset; this experimental result satisfied the Association for the Advancement of Medical Instrumentation, and the British Hypertension Society standards for BP monitoring devices. The experimental results demonstrated the practical application of the wireless and flexible biosensor patch for continuous physiological signal monitoring with Internet of Medical Things-connected healthcare applications.

Low-level laser therapy (LLLT), also known as photobiomodulation, is a safe and noninvasive method for various dermatological applications. However, most LLLT devices have limitations, such as low flexibility, high energy consumption, and huge equipment size, limiting their usage in daily life and clinical treatment. This study presents a flexible and wireless light emitting diode (LED) patch with an internet of thing (IoT) healthcare platform for wound healing applications. The flexible LED patch was designed with a high-efficiency performance of thermal stability, device uniformity, and mechanical durability for skin-attachable phototherapies application and clinical use. The application of a smartphone app with an IoT-connected healthcare platform for the flexible LED patch opens tremendous opportunities for the development of a remote healthcare system with cost-effectiveness in the future. In wound healing test on normal human fibroblasts, the LED light was proven to have no cytotoxic effect with high fibroblast proliferation and fibroblast migration (over 16% compared to control) under various light irradiations. Furthermore, a high association between wavelengths and exposure duration with biologic responses and migration effects was indicated in the study. The cell proliferation and migration experiments show the necessity of optimizing LED wavelength, radiation doses for better clinical assessment. Based on the results, the flexible LED patch is expected to be a suitable photomedical device for various types of dermatology applications.

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