Ternary mixed monolayers for simultaneous DNA orientation control and surface passivation for label free DNA hybridization electrochemical sensing

Ternary Monolayer Interfaces for Ultrasensitive and Direct Bioelectronic Detection of Nucleic Acids in Complex Matrices

“…The detection limit obtained with the ternary monolayer is notably lower compared to those reported previously for SAMbased electrochemical DNA sensors. For example, it is 100-1000-fold lower than the detection limits reported recently for a binary SHCP + OEG layer [42] or ternary SHCP + MPA + MCH monolayers [37,40], and 10 000 times lower than that obtained with the common binary layer [22]. In order to demonstrate the enhanced reproducibility of the new ternary layer in comparison to the precision of common binary layer described by other authors [35,36,38], Wangs group performed a detailed study comparing the response for 1 nM target DNA, the noise level and the S/N ratio provided by different batches of chips and different preparation days using the common binary or the new ternary monolayers.…”

“…As a result, very low limits of detection (LLOD) of 7 and 17 pM (28 and 68 amol, respectively) were established in 100 % untreated urine and serum samples, respectively, which are two orders of magnitude more sensitive than other sensors reported in the literature in raw samples. In addition, this new bioplatform displayed excellent antifouling properties even after 24 h immersion in the select- In comparison with other non-fouling DNA interfaces reported in the literature, the dithiol-based SAM allow the achievement of a 100-1000-fold lower limit of detection [37,40,42] and offer the possibility to detect picomolar target DNA concentrations directly in complex biological matrices without previous dilution or pretreatment. In spite of the demonstrated sensitivity and performance in complex samples of the new ternary monolayers additional work is required in order to improve the prolonged stability of these new SAMs.…”

“…Ternary monolayers of SHCP, MCH and MPA prepared by sequential absorption method on both conven- tional wire electrode and 100 nm scale gold-coated silicon chips, have been suggested recently by Dharuman et al [37,40] for enhancing the performance of electrochemical genosensors. This new multicomponent ternary layer interface allows a 60-80 % discrimination effect in comparison with the~20-30 % provided with conventional binary SAM [37,40] and enables the detection of 10 pM target DNA in pure buffer matrix [40].…”

“…In most cases it is difficult to detect trace levels of the target DNA. Recent attempts to address these challenges employed common non-fouling components, such as poly(ethylene glycol) (PEG)-based materials, or by introducing 3-mercaptopropionic acid (MPA) as a third thiol component [37,40]. Other SAM routes based on the co-immobilization of oligo(ethylene glycol) (OEG)-terminated thiols and SHCP have demonstrated effective minimization of nonspecific adsorption and lower detection limits down to the picomolar level in the presence of diluted biological samples (10 % serum) [16,18,19].…”

Rapid and Label-Free Detection of Interferon Gamma via an Electrochemical Aptasensor Comprising a Ternary Surface Monolayer on a Gold Interdigitated Electrode Array

“…To circumvent these challenges research groups have added a third thiol component to help improve the filling density of the SAM and hence improve nonspecific adsorption of nontarget analyte to the Au surface. 37,42,43 In this work, we utilize the HDT and MCH in conjunction with a RNA ACP to create a ternary surface monolayer that can be immobilized on the surface of the Au IDE to selectively detect IFN-γ in biological solutions ( Figure 1). The Au IDEs were biofunctionalized with the ACP/ HDT-MCH ternary surface monolayer via thiol-Au chemisorption following similarly published protocols and as explained in detail in the Methods section.…”