Biocompatible hydrogel nanoparticles are obtained by a process where thermo responsiveness is obtained by a mixture of appropriate monomers that, upon heating, tune the formation of well-defined nano self-assemblies of different sizes which are further polymerized. This strategy leads to nanoparticles with varied sizes from 20 to 390 nm that correlate with the starting ratio of the monomers in the thermo responsive mixtures. Physico-chemical characterization of the nanoparticles, as well as in vitro and in vivo biocompatibilityassays, demonstrate their lack of toxicity and thus their applicability to biological systems. The nanoparticles can be labeled with fluorescent probes, and their intracellular fate can be visualized and quantified using confocal microscopy. Their uptake by live cells and distribution in whole developing animals is reported. On the basis of our results, a mechanism of nanoparticle formation is suggested. The nanoparticles can be embedded into an inorganic micrometric matrix that allows biology-relevant peptide synthesis on their surface towards their use as cell sensors. The lack of toxicity makes these nanoparticles especially attractive for biological applications such as screening and bio-sensing. Finally, we have demonstrated that these nanoparticles can be used for the synthesis of bio-relevant peptides opening the posibility of their application as biosensors.
