Zn<sup>2+</sup>-Modified Nonmetal Porphyrin-Based Metal–Organic Frameworks with Improved Electrochemiluminescence for Nanoscale Exosome Detection
Yisha Wang, Jiangnan Shu, Aihua Lyu, Manli Wang, Chao Hu, Hua Cui
Abstract
Exploring effective and robust strategies for enhancing electrochemiluminescence (ECL) emissions of porphyrin-based metal–organic frameworks (MOFs) is of great importance for expanding their applications in bioassays. Herein, a simple, convenient, and effective endogenous strategy of post-synthesis-modified Zn 2+ was proposed to enhance ECL of nonmetal porphyrin-based MOFs. The ECL emissions of porphyrin-cobuilt UiO-66-NH 2 (TCPP/UiO-66-NH 2 ), PCN-224, PCN-222, and Ce–TCPP–LMOF could be enhanced 31.9, 47.1, 49.9, and 19.2 times, respectively. By studying TCPP/UiO-66-NH 2 nanoluminophores as a model, Zn 2+ was incorporated into TCPP/UiO-66-NH 2 through the coordination of Zn and pyrrolic N of TCPP. The ECL enhancement was attributed to the conversion of TCPP to ZnTCPP with high emission efficiency and MOFs could enrich co-reactants, shorten the ion/electron-transfer distance, and render electrochemical activation of porphyrin luminophores. On this basis, a simple ECL biosensor for detecting nanoscale exosomes was developed based on the boosted ECL signal of Zn–TCPP/UiO-66-NH 2 nanoluminophores without additional recognition and amplification elements. The ECL biosensor exhibited good sensitivity with a detection range from 1.00 × 10 4 to 3.16 × 10 6 particles/μL and a detection limit of 9.08 × 10 3 particles/μL ( S / N = 3). The linear range and detection limit of the proposed label-free ECL biosensor are better than most of the existing label-free methods for detecting exosomes, indicating its good performance as a powerful tool for accurate and sensitive detection of HepG 2 -derived exosomes. As a result, this work provides inspiration for exploring strategies to enhance ECL efficiencies of porphyrin-based MOFs, which has important application prospects in sensitive bioassays.