Aptamer-Based Biosensors for Label-Free Voltammetric Detection of Lysozyme

Abstract

This paper reports a simple electrochemical approach for the detection of the ubiquitous protein lysozyme using aptamer-modified electrodes. Anti-lysozyme DNA aptamers were immobilized on gold surfaces by means of self-assembly, for which the surface density of aptamers was determined by cyclic voltammetric (CV) studies of redox cations (e.g., [Ru(NH3)6]3+) bound to the surface via electrostatic interaction with the DNA phosphate backbone. Upon incubation of the electrode with a solution containing lysozyme, the CV response of surface-bound [Ru(NH3)6]3+ changed substantially, and the relative decrease in the integrated charge of the reduction peak can be tabulated as a quantitative measure of the protein concentration. It is significant that the on-chip protein/aptamer binding constant and the optimized surface density to achieve the best detection limit can be evaluated. This biosensor is label-free and offers an alternative, sensitive, and versatile method for protein detection, which is beneficial to the ever-growing interests of fabricating portable bioanalytical devices with simple electrical readout protocols.

Detection of protein aggregation with a Bloch surface wave based sensor

“…The lowest HEWL concentration in which aggregates are discriminated is 140 M. The sensor is able to detect proteins near to physiological concentrations (3.5 M or lower) [25]. However, the discrimination of fibril formation at the very early stages of aggregation is only achieved at higher concentrations.…”

Advances in Aptamer-Based Biosensors for Food Safety

“…-- (Tran et al, 2010) DNA 3 nM Electrochemical (voltammetry) 0.5 µg/mL (Cheng et al, 2007) (Kirby et al, 2004) RNAFluorescence (microarray) 70 fM (Collett et al, 2005) Section 2.3 will describe these systems briefly, while three biosensor platforms targeting pathogens in food will be discussed in Section 2.4.…”

“…Another noteworthy example that has been studied over the past few years is egg-white lysozyme, a protein considered to be an allergen-trigger in consumers with egg allergies. A few promising aptasensor platforms developed so far include label-free voltammetric assays (Cheng et al, 2007), Faradaic impendance spectroscopy (Rodriguez et al, 2005) and RNA microarray technology (Collett et al, 2005).…”

Aptamer-Based Electrochemical Sensing of Lysozyme

“…click chemistry between azide-modified gold particles and alkyne-terminated aptamers ( Figure 2D) [60] 5. electrostatic interactions between the negatively-charged phosphate backbone of the aptamer and positively-charged materials ( Figure 2E), such as polypyrrole, Fe 2 O 3 and ferrocene-appended poly(ethyleneimine) (Fc-PEI) in a layer-by-layer approach or amine-rich films of plasma-polymerized propargylamine in a Cu 2 O@rGO@PpPG-modified gold electrode [74,78,84,88] 6. affinity binding based on biotin-avidin [80] or host-guest interactions [89] (Figure 2F) 7. hybridization to a partially complementary DNA strand, previously immobilized on the electrode surface ( Figure 2G) [96] Chemosensors 2016, 4, 10 7 of 21 The majority of electrochemical aptasensors for lysozyme used thiolated aptamers on gold electrode, that is following Strategy (C) [46,62,87,91,94]. To increase the aptamer loading, a popular approach relies on modifying the electrodes with Au nanoparticles [47,76].…”

“…The majority of electrochemical aptasensors for lysozyme used thiolated aptamers on gold electrode, that is following Strategy (C) [46,62,87,91,94]. To increase the aptamer loading, a popular approach relies on modifying the electrodes with Au nanoparticles [47,76].…”