NIR-emitting chiral gold nanoclusters coated with γ-cyclodextrin are pH sensitive: Application as biomarker.

Change in cellular pH due to onset of certain malfunctions needs to be tracked quickly so that treatment to cure such incidents may be started immediately. For example, microenvironment of a developing tumor is acidic due to high metabolic rate as well as low oxygen supply. Hence biomarkers that can sharply sense transition in pH could be of great use in the early detection of tumor formation. In the present work, a unique pH sensitive non-cytotoxic gold nanocluster based probe has been synthesized to precisely detect sharp change in biological pH. The gold nanoclusters were coated with dihydrolipoic acid incorporated γ-cyclodextrins. Measurements with steady state fluorometric changes reveal the sensibility of the probes through obvious wavelength shift depending on the changes in the microenvironment. The nanocluster based probe has been successfully applied to detect cancer cells with high precision. FROM THE CLINICAL EDITOR: Biomarkers sensitive to physiological environment have extensive uses in nanomedicines. pH sensitive ultrasmall gold nanoclusters coated with dihydrolipoic acid incorporated γ-cyclodextrins indicate Changes in cellular pH, therefore certain malfunctions. The new biomarker could be useful to detect tumor calls.