Molecularly engineered charge-conversion of proteins for sensitive biosensing.

Area of Science:

• Biochemistry
• Analytical Chemistry
• Materials Science

Background:

• Potentiometric biosensing requires sensitive detection of protein interactions.
• Modifying protein surface charges can improve signal transduction.
• Maintaining protein structure and bioactivity during modification is crucial.

Purpose of the Study:

• To develop a site-selective chemical modification strategy for enhancing protein biosensing signals.
• To investigate the impact of charge conversion on protein adsorption detection.
• To demonstrate the feasibility of in situ modification for real-time biosensing.

Main Methods:

• Exogenous acylation and glycation reactions to modify primary amines and guanidinium groups.
• Mass spectrometry to confirm site-selective adduct formation on lysine and arginine residues.
• Extended gate-field effect transistor (FET) to measure real-time protein adsorption onto self-assembled monolayers (SAMs).

Main Results:

• Site-selective charge conversion of surface-exposed residues was confirmed without compromising protein integrity.
• Succinic modification of bovine serum albumin (BSA) increased negative charge density fivefold.
• FET measurements showed a threefold signal increase for succinylated BSA and an elevenfold increase for modified lysozyme adsorption.

Conclusions:

• Site-selective charge conversion serves as an effective molecular label for potentiometric biosensing.
• This approach significantly amplifies detection signals while preserving protein conformational integrity.
• In situ modification during potentiometry offers a novel strategy for sensitive protein analysis.