ACS Appl Mater Interfaces 2019 Feb 30;11(6):5804-5811. Epub 2019 Jan 30.
Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Analytical Chemistry for Living Biosystems, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China.
Metal-peptide interactions provide plentiful resource and design principles for developing functional biomaterials and smart sensors. Pb, as a borderline metal ion, has versatile coordination modes. The interference from competing metal ions and endogenous chelating species greatly challenges Pb analysis, especially in complicated living biosystems. Herein, a biomimetic peptide-based fluorescent sensor GSSH-2TPE was developed, starting from the structure of a naturally occurring peptide glutathione. Lewis acid-base theory was employed to guide the molecular design and tune the affinity and selectivity of the targeting performance. The integration of peptide recognition and aggregation-induced emission effect provides desirable sensing features, including specific turn-on response to Pb over 18 different metal ions, rapid binding, and signal output, as well as high sensitivity with a detection limit of 1.5 nM. Mechanism investigation demonstrated the balance between the chelating groups, and the molecular configuration of the sensor contributes to the high selectivity toward Pb complexation. The ion-induced supramolecular assembly lights up the bright fluorescence. The ability to image Pb in living cells was exhibited with minimal interference from endogenous biothiols, no background fluorescence, and good biocompatibility. With good cell permeability, GSSH-2TPE can monitor changes in Pb levels and biodistribution and thus predict possible damage pathways. Such metal-peptide interaction-based sensing systems offer tailorable platforms for designing bioanalytical tools and show great potential for studying the cell biology of metal ions in living biosystems.