Oxygen-releasing biomaterials for regenerative medicine.

Oxygen is critical to the survival, function and fate of mammalian cells. Oxygen tension controls cellular behavior through metabolic programming, which in turn controls tissue regeneration. A variety of biomaterials with oxygen-releasing capabilities have been developed to provide oxygen supply to ensure cell survival and differentiation for therapeutic efficacy, and to prevent hypoxia-induced tissue damage and cell death. However, controlling the oxygen release with spatial and temporal accuracy is still technically challenging. In this review, we provide a comprehensive overview of organic and inorganic materials available as oxygen sources, including hemoglobin-based oxygen carriers (HBOCs), perfluorocarbons (PFCs), photosynthetic organisms, solid and liquid peroxides, and some of the latest materials such as metal-organic frameworks (MOFs). Additionally, we introduce the corresponding carrier materials and the oxygen production methods and present state-of-the-art applications and breakthroughs of oxygen-releasing materials. Furthermore, we discuss the current challenges and the future perspectives in the field. After reviewing the recent progress and the future perspectives of oxygen-releasing materials, we predict that smart material systems that combine precise detection of oxygenation and adaptive control of oxygen delivery will be the future trend for oxygen-releasing materials in regenerative medicine.

A photo-responsive membrane for tailored drug delivery with spatially and temporally controlled release.

Accurate delivery of therapeutics to tumor regions and effective sparing of normal tissue structures are important principles for the treatment of widespread metastases or malignant lesions in close proximity to vital organs. However, the currently available drug delivery techniques do not support precise drug release within the identified disease margins. We propose a tailored drug delivery strategy that utilizes a photo-responsive material in combination with tumor margin imaging for automated and tailored release of therapeutics. As a proof of concept, a poly(ethylene oxide)-b-PSPA (PEO-b-PSPA) diblock copolymer is synthesized by spiropyran (SP) polymerization. A photo-responsive membrane (PRM) is formed and irradiated with light sources of different wavelengths. Switching irradiation between ultraviolet light (UV) and green light (Vis) controls the permeability of the PRM in coincidence with the programmed irradiation patterns. The dynamic process of photo-switchable drug permeation through the PRM is modeled and compared with the experimental results. The strategy of tailored drug release is verified using both regular geometric shapes and metastatic cancer images. The therapeutic effect of this tailored drug release strategy is demonstrated in vitro in human breast cancer cells. Our pilot study implies the technical potential of using photo-responsive carriers for image-guided chemotherapy with precisely controlled drug release patterns.