6-mercapto-1-hexanol and 1-6-hexanedithiol

While high storage stability of sequence-selective DNA biosensors is crucial towards their routine applications, commonly used electrochemical hybridization biosensors are characterized with limited storage stability. In this article we demonstrate that recently developed ternary thiolated monolayers impart dramatic improvement in the storage stability of DNA electrochemical biosensors. In particular, highly stable multicomponent interfaces are prepared by co-immobilizing the thiolated capture probe (SHCP) with 1,6-hexanedithiol (HDT) on gold substrates, followed by the incorporation of 6-mercapto-1-hexanol (MCH) diluent. The resulting (SHCP/HDT+MCH) DNA hybridization recognition platform offers substantially higher storage stability compared to conventional binary (SHCP+MCH) monolayers. The (SHCP/HDT+MCH) ternary monolayers maintain their initial signal (S)-to-noise (N) ratio (S/N) over a prolonged 3 months period upon storage at 4 °C, compared to the rapid sensitivity loss observed using the common binary interfaces. This attractive stability performance promises the convenient usage of pre-prepared electrodes after prolonged time storage without any treatment. Such dramatic improvements in the storage stability have been achieved through a rational optimization of the concentration ratio of the SHCP and the other components of the ternary SAM. The improved storage stability of SHCP/HDT+MCH interfaces observed at higher concentrations of SHCP is attributed to a hindered displacement of SHCP by MCH in the resulting compact layers. The ability to design highly stable nucleic acid interfaces using common chemicals obviates the need of using specialized expensive reagents.

Topics: Animals; Biosensing Techniques; DNA; DNA Probes; Electrochemistry; Electrodes; Gold; Hexanols; Signal-To-Noise Ratio; Sulfhydryl Compounds; Temperature; Time Factors

The development of rapid, low-cost and reliable diagnostic methods is crucial for the identification and treatment of many diseases. Screen-printed gold electrodes (Au/SPEs), coated with a ternary monolayer interface, involving hexanedithiol (HDT), a specific thiolated capture probe (SHCP), and 6-mercapto-1 hexanol (MCH) (SHCP/HDT/MCH) are shown here to offer direct and sensitive detection of nucleic acid hybridization events in untreated raw biological samples (serum, urine and crude bacterial lysate solutions). The composition of the ternary monolayer was modified and tailored to the surface of the Au/SPE. The resulting SHCP/HDT/MCH monolayer has demonstrated to be extremely useful for enhancing the performance of disposable nucleic acid sensors based on screen-printed electrodes. Compared to common SHCP/MCH binary interfaces, the new ternary self-assembled monolayer (SAM) resulted in a 10-fold improvement in the signal (S)-to-noise (N) ratio (S/N) for 1 nM target DNA. The SHCP/HDT/MCH-modified Au/SPEs allowed the direct quantification of the target DNA down to 25 pM (0.25 fmol) and 100 pM (1 fmol) in undiluted/untreated serum and urine samples, respectively, and of 16S rRNA Escherichia coli (E. coli) corresponding to 3000 CFU μL(-1) in raw cell lysate samples. The new SAM-coated screen-printed electrodes also displayed favorable non-fouling properties after a 24h exposure to raw human serum and urine samples, offering great promise as cost-effective nucleic acid sensors for a wide range of decentralized genetic tests.

Topics: Biosensing Techniques; Cost-Benefit Analysis; DNA; Electrochemical Techniques; Electrodes; Escherichia coli; Gold; Hexanols; Humans; Nucleic Acids; Reproducibility of Results; RNA, Bacterial; RNA, Ribosomal, 16S; Sulfhydryl Compounds