We report the synthesis of nanosized particles based on bio-compatible polyethylene-polypropylene glycol (pluronic) materials. In aqueous solution, mini-emulsification of pluronic with two pyrimidine chromophores leads to nanoparticles with hydrodynamic radius below 100 nm. We have demonstrated that these probes exhibit a fast and fully reversible solvatochromic behaviour from yellow to purple when decreasing the pH solution. The average acidity constant of both dyes incorporated in pluronic mainly originate from the non-substituted pyrimidine (1,3-diazine) core. The close functionalization of the pyrimidine with pyridyl groups leads to a tridentate ligand suitable for metal cations complexation