Diabetic nephropathy is a long-term kidney disease that affects patients with diabetes. Early detection of diabetic nephropathy can help prevent dreadful consequences like irreversible renal damage. MicroRNAs (miRNAs) are potential biomarkers that could help diagnose diabetic nephropathy in the early stages.
Study: Ultrasensitive electrochemical biosensor for microRNA-377 detection based on MXene-Au nanocomposite and G-quadruplex nano-amplification strategy. Image Credit: Eviart/Shutterstock.com
In an article recently published in the journal Electrochimica Acta, an electrochemical biosensor was developed for ultrasensitive detection of miRNA-377. The biosensor was based on the guanine (G)-quadruplex nano-amplification strategy and MXene-gold (Au) nanocomposites.
The nanocarriers leveraged the combined effects of Au nanoparticles (NPs) and MXene-Au nanocomposites and exhibited outstanding electronic conductivity. Furthermore, massive active sites generated by Au-S bonds on nanocarriers helped capture and immobilize DNA. Modifying AuNPs with G-rich sequence DNA detection probes helped in signal amplification.
Moreover, the transition of G-rich detection probes to G-quadruplex enhanced the interactions between methylene blue (MB) and G-quadruplex, which reflected the presence of miRNA-377 (even in trace quantities) with an enhanced electrochemical signal.
Detection of miRNA-377 and Role of MXene in Biosensors
miRNAs are short noncoding RNAs that play a vital role in various biological processes, including gene regulation, differentiation, and apoptosis. However, aberrant expression of miRNAs is associated with many human diseases. In addition, miRNAs are secreted into extracellular fluids. These extracellular miRNAs have been widely reported as potential biomarkers for various diseases and serve as signaling molecules to mediate cell-to-cell communications.
Diabetic nephropathy is a microvascular complication found in diabetic patients (both type I and II) and is a leading cause of renal damage. Previous studies mentioned that miRNA-377 is related to the development of diabetic nephropathy. To this end, microalbuminuria is a preferred indicator for early diagnosis of diabetic nephropathy since the prognostic indicator has limited specificity and sensitivity towards miRNA-377.
Previous reports mentioned the overexpression of miRNA-377 in mouse models suffering from diabetic nephropathy and promoted fibronectin synthesis. Moreover, since miRNAs-377 are stable in body fluids, they serve as a non-invasive marker in diagnosing diabetic nephropathy.
However, a sensitive, accurate, and rapid detection and quantification method for miRNA-377 remains challenging due to its high homology, short sequence, and low abundance (ranging from femto- to nanomolar) in body fluids.
Although conventional miRNA-377 detection techniques, including northern blotting, microarrays, and real-time quantitative polymerase chain reaction, can detect and quantify miRNA-377 in human serum, these techniques are expensive, time-consuming, and have low sensitivity.
Transition metal carbides, carbonitrides, and nitrides or MXenes are two-dimensional (2D) materials. MXenes are coupled with other nanomaterials to achieve high sensitivity in biosensors. For example, MoS2/Ti3C2 nanohybrids and Ti3C2Tx@FePcQDs-based biosensors were previously developed with a limit of detection (LOD) of 0.43 femtomoles and 4.3 attomoles, respectively.
Electrochemical Biosensor for miRNA-377 Detection
In the present work, an ultrasensitive electrochemical biosensor was developed based on the G-quadruplex nano-amplification strategy and MXene-Au nanocomposite to detect miRNA-377 in human serum samples. The auto-reduction of AuNPs on MXene nanosheets resulted in the formation of MXene-Au nanocomposite that served as an electrode substrate and helped in the attachment of the capture probe (CP).
On exposing the biosensor to miRNA-377, CP interacted with G-rich detection probes modified on AuNPs (DP-AuNPs) and formed a sandwich complex at the interface. Additionally, the activation of potassium ion (K+) resulted in the integration of methylene blue (MB) into G-quadruplex units, forming DP-AuNPs with amplified electrochemical signals.
Thus, the developed biosensor showed ultra-sensitive detection of miRNA-377 with a linear detection range from 10 attomoles to 100 picomoles and a very small LOD of 1.35 attomoles. Contrary to biosensors based on other nanocomposites and other miRNA-377-based biosensors reported to date, the present electrochemical biosensor was devoid of reverse transcription process or thermal cycling, indicating the compliance of the electrochemical biosensor with miRNA-377 sensing requirements of sensitivity, convenience, stability, and specificity.
Moreover, the electrochemical biosensor constructed in the present work showed good selectivity towards miRNA-377 in human serum samples with good sensitivity, indicating the promising application of the as-constructed biosensor in early clinical diagnosis and biological research for diabetic nephropathy.
Overall, an electrochemical biosensor with ultra-sensitivity was developed based on MXene-Au and MB/DP-AuNPs. The former served as a substrate material and later signal amplifying material. The synergic effect of MXene-Au nanocomposites accelerated the electrode surface’s electron transfer and improved the specific surface area.
Furthermore, the hybridization of DP-AuNPs with CP resulted in a G-quadruplex structure to bind with MB. Thus, the as-constructed biosensor showed a detection range for miRNA-377 from 10 attomoles to 100 picomoles with LOD as low as 1.35 attomoles.
Additionally, the developed electrochemical biosensor had promising applications in detecting miRNA-377 in human serum samples, suggesting enhanced selectivity, high sensitivity, and stability of the present miRNA sensing platform in clinical applications.
Wu, Q., Li, Z., Liang, Q., Ye, R., Guo, S., Zeng ,S., Hu ,J et al. (2022). Ultrasensitive electrochemical biosensor for microRNA-377 detection based on MXene-Au nanocomposite and G-quadruplex nano-amplification strategy. Electrochimica Acta.https://www.sciencedirect.com/science/article/pii/S0013468622011021?via%3Dihub