Charge-Sensitive Optical Detection of Small Molecule Binding Kinetics in Normal Ionic Strength Buffer

An innovative electrophoresis-coupled electrochemiluminescence immunosensor for rapid and sensitive detection of carcinoembryonic antigen

Electrochemiluminescence (ECL) immunosensor provides unique advantages for the sensitive biomarker detection. However, the lengthy detection duration and plentiful system interferences have hindered their development. Here, we present an innovative approach in which electrophoresis coupled with ECL immunoassay was implemented to construct an electric field-enhanced ECL immunosensor for efficient detection of carcinoembryonic antigen (CEA). The electrophoresis device can be regarded as an electric field-driven incubation system, with a working electrode as the anode and a platinum disk as the cathode. Upon applying direct voltage, CEA was swiftly transported to the electrode surface via an upward electric field force, drastically cutting the CEA incubation time from 60 min to just 5 min-a 12-fold reduction compared to traditional methods. Our method also achieved a broad linear detection range from 10-2 to 104 pg/mL, with a lower detection limit of 2.33 fg/mL. Additionally, we utilized the COMSOL Multiphysics-based numerical model and substantial experiment results, demonstrating that the incorporation of an electrophoresis system has allowed for rapid detection with high sensitivity, thereby boosting the overall efficiency of the ECL immunosensor. This study underscores the potential of the electric field-enhanced ECL immunosensor for broad application in the biodetection field.

Recent Advances in Real-Time Label-Free Detection of Small Molecules

The detection and analysis of small molecules, typically defined as molecules under 1000 Da, is of growing interest ranging from the development of small-molecule drugs and inhibitors to the sensing of toxins and biomarkers. However, due to challenges such as their small size and low mass, many biosensing technologies struggle to have the sensitivity and selectivity for the detection of small molecules. Notably, their small size limits the usage of labeled techniques that can change the properties of small-molecule analytes. Furthermore, the capability of real-time detection is highly desired for small-molecule biosensors' application in diagnostics or screening. This review highlights recent advances in label-free real-time biosensing technologies utilizing different types of transducers to meet the growing demand for small-molecule detection.

Charge-Sensitive Optical Detection of Binding Kinetics between Phage-Displayed Peptide Ligands and Protein Targets

Phage display technology has been a powerful tool in peptide drug development. However, the supremacy of phage display-based peptide drug discovery is plagued by the follow-up process of peptides synthesis, which is costly and time consuming, but is necessary for the accurate measurement of binding kinetics in order to properly triage the best peptide leads during the affinity maturation stages. A sensitive technology is needed for directly measuring the binding kinetics of peptides on phages to reduce the time and cost of the entire process. Here, we show the capability of a charge-sensitive optical detection (CSOD) method for the direct quantification of binding kinetics of phage-displayed peptides to their target protein, using whole phages. We anticipate CSOD will contribute to streamline the process of phage display-based drug discovery.