Building and Testing of a MUHEG Capped Quantum Dot Lead Biosensor Specific Against Mercury Quenching

Abstract

Biosensors utilize biological and physicochemical detector component to detect an analyte. A metalloprotein backbone reporter element was elicited as the biological component to the biosensor. The lead binding metalloprotein (PbBP) used is of the hinge motion binding protein (HMBP) family. Hinge motion binding proteins undergo a conformational change in protein structure, PbBP specifically brings the amino and carboxyl terminus of the protein into close proximity. Physicochemical detection is produced with an electron accepting quantum dot and its complimentary electron donor a ruthenium(II) metal complex. Physical attributes to the biosensor provide the mechanism for analyte detection. The change in protein structure allows the n-terminus positioned ruthenium(II) metal complex to donate an electron to the c-terminus positioned quantum dot (QD). The transferred electron ceases the QD’s fluorescence, this is termed a “quench.” In previous experiments lead biosensors have proven effective at detecting lead concentrations at low levels (5 μm). However the biosensor finds lacking in its specificity. With experiments conducted in the presence of mercury(II) a 90 % quench was registered. A metallothionein (MT) capping group was distinguished as problematic for its high cysteine count. In aim to rectify the lead biosensor’s quench and provide better specificity for it a (1-Mercaptoundec-11- yl)hexa(ethylene glycol), MUHEG, capping group was synthesized and replaced the MT capping group on the QDs