Disclosed are methods, compositions and kits pertaining to detecting and/or measuring biological analytes. In certain embodiments the disclosure relates to detection and measurement of lactate, pyruvate, oxygen and/or hydrogen peroxide. In some aspects and embodiments provided are biosensors that may be or include nanoparticles, microparticles and/or nano-in-micro matrices. The methods and compositions disclosed may have uses in purpose of diagnosis and treatment of diseases, fitness and health monitoring in sports, in space medicine, in food applications and the food industry, in pharmaceutical applications and the pharmaceutical industry, for fermentation monitoring, and in polymer manufacturing applications. In some embodiments and aspects, the disclosure relates to minimally invasive biosensors and/or biosensors that may be used for continuous monitoring.
