The spectral relaxation dynamics and the molecular crowding effect of silver nanoclusters synthesized in the polymer scaffold

We have performed a comprehensive study on the spectral relaxation dynamics of silver nanoclusters (AgNCs) synthesized in poly(methacrylic acid) (PMAA). In different polymer conformations and solvents, the spectral relaxation dynamics of PMAA-AgNCs can be globally fitted by a bi-exponential decay, the short component is about 0.2-0.3 ns, whereas the long component is in the range 1-3 ns. The spectral relaxation is associated with the energy transfer dynamics and the excitation of multiple emissive AgNCs. In this study, we have demonstrated the feasibility of using AgNCs as a fluorescent probe for fluorescence anisotropy studies. Meanwhile, the molecular crowding effects of the PMAA-AgNCs were addressed using the Triton X-100 reverse micelles. The results indicate that the fluorescence quantum yield of the AgNCs will be significantly increased under crowded conditions, which is beneficial for their usage in intracellular imaging studies.