Ultrasound (US) is a kind of acoustic wave with frequency higher than 20 kHz. Learning from the echo detection ability of bats and dolphins, scientists applied US for clinical imaging by sending out US waves and detecting echoes with shifted intensities and frequencies from human tissue. US has long played a critical role in noninvasive, real-time, low-cost and portable diagnostic imaging. With the in-depth study of US in multidisciplinary fields, US and US-responsive materials have shown practical value in not only disease diagnosis, but also disease treatment. In this review, we introduce the recently proposed and representative US-responsive materials for biomedical applications, including diagnostic and therapeutic applications. We focused on US-mediated physicochemical therapies, such as sonodynamic therapy, high-intensity focused US ablation, sonothermal therapy, thrombolysis, etc, and US-controlled delivery of chemotherapeutics, gases, genes, proteins and bacteria. We conclude with the current challenges facing the clinical translation of smart US-responsive materials and prospects for the future development of US medicine.

Intestinal diseases that have high mortality and morbidity rates and bring huge encumbrance to the public medical system and economy worldwide, have always been the focus of clinicians and scientific researchers. Early diagnosis and intervention are valuable in the progression of many intestinal diseases. Fortunately, the emergence of sensor materials can effectively assist clinical early diagnosis and health monitoring. By accurately locating the lesion and sensitively analyzing the level of disease markers, these sensor materials can help to precisely diagnose the stage and state of lesions, thereby avoiding delayed treatment. In this review, we provide comprehensive and in-depth knowledge of diagnosing and monitoring intestinal diseases with the assistance of sensor materials, particularly emphasizing their design and application in bioimaging and biodetection. This review is dedicated to conveying practical applications of sensor materials in the intestine, critical analysis of their mechanisms and applications and discussion of their future roles in medicine. We believe that this review will promote multidisciplinary communication between material science, medicine and relevant engineering fields, thus improving the clinical translation of sensor materials.

Antimicrobial resistance (AMR) poses a huge threat to human health. It is urgent to explore efficient ways to suppress the spread of AMR. Antibacterial nanozymes have become one of the powerful weapons to combat AMR due to their enzyme-like catalytic activity with a broad-spectrum antibacterial performance. However, the inherent low catalytic activity of nanozymes limits their expansion into antibacterial applications. In this regard, a variety of advanced chemical design strategies have been developed to improve the antimicrobial activity of nanozymes. In this review, we have summarized the recent progress of advanced strategies to engineer efficient nanozymes for fighting against AMR, which can be mainly classified as catalytic activity improvement, external stimuli, bacterial affinity enhancement, and multifunctional platform construction according to the basic principles of engineering efficient nanocatalysts and the mechanism of nanozyme catalysis. Moreover, the deep insights into the effects of these enhancing strategies on the nanozyme structures and properties are highlighted. Finally, current challenges and future perspectives of antibacterial nanozymes are discussed for their future clinical potential.

Micro/nanomaterial-based drug and cell delivery systems play an important role in biomedical fields for their injectability and targeting. Microfluidics is a rapidly developing technology and has become a robust tool for preparing biomaterial micro/nanocarriers with precise structural control and high reproducibility. By flexibly designing microfluidic channels and manipulating fluid behavior, various forms of biomaterial carriers can be fabricated using microfluidics, including microspheres, nanoparticles and microfibers. In this review, recent advances in biomaterials for designing functional microfluidic vehicles are summarized. We introduce the application of natural materials such as polysaccharides and proteins as well as synthetic polymers in the production of microfluidic carriers. How the material properties determine the manufacture of carriers and the type of cargoes to be encapsulated is highlighted. Furthermore, the current limitations of microfluidic biomaterial carriers and perspectives on its future developments are presented.

Biomimetic scaffolds with extracellular matrix (ECM)-mimicking structure have been widely investigated in wound healing applications, while insufficient mechanical strength and limited biological activity remain major challenges. Here, we present a microfluidic 3D printing biomimetic polyhydroxyalkanoates-based scaffold with excellent mechanical properties and hierarchical porous structures for enhanced wound healing. This scaffold is composed of poly(3-hydroxybutyrate-4-hydroxybutyrate) and polycaprolactone, endowing it with excellent tensile strength (2.99 MPa) and degradability (80% of weight loss within 7 d). The ECM-mimicking hierarchical porous structure allows bone marrow mesenchymal stem cells (BMSCs) and human umbilical vein endothelial cells (HUVECs) to proliferate and adhere on the scaffolds. Besides, anisotropic composite scaffolds loaded with BMSCs and HUVECs can significantly promote re-epithelization, collagen deposition and capillary formation in rat wound defects, indicating their satisfactory in vivo tissue regenerative activity. These results indicate the feasibility of polyhydroxyalkanoates-based biomimetic scaffolds for skin repair and regeneration, which also provide a promising therapeutic strategy in diverse tissue engineering applications.