Tumor microenvironment (TME) is a pivotal factor in tumor progression. Here we report an injectable multifunctional hydrogel microsphere with responsive photonic structure for in vivo monitoring of TME pH. The pH determination is based on measurement of the characteristic reflection peak of the hydrogel microsphere in near-infrared (NIR) region that is sensitive to pH, and decreasing pH leads to a blue shift of the peak. With deep tissue penetration ability of the NIR light, the pH of normal and tumor tissues of mice are continuously monitored in vivo using the microspheres injected subcutaneously. The biocompatibility and the cytotoxicity of the material is investigated based on MTT assays to evaluate its potential for long-term continuous in vivo monitoring of TME pH. A drug for cancer treatment is also preloaded into the hydrogel microsphere for simultaneous drug release in TME and monitoring of the treatment effectiveness of drug by the TME pH tests.

肿瘤微环境（TME）是肿瘤进展的关键因素。在这里，我们报告可注射的多功能水凝胶微球具有响应性的光子结构，用于体内监测TME pH值。pH的确定基于对水凝胶微球在对pH敏感的近红外（NIR）区域中的特征反射峰的测量，并且pH值降低会导致峰的蓝移。具有近红外光的深层组织穿透能力，可使用皮下注射的微球体内连续监测小鼠正常组织和肿瘤组织的pH值。基于MTT分析研究了该材料的生物相容性和细胞毒性，以评估其对TME pH值进行长期连续体内监测的潜力。