Advancing 5-hydroxymethylcytosine detection: A review of innovative nanoparticle-based electrochemical and optical...

5-Hydroxymethylcytosine (5-hmC) is a hydroxylated and methylated cytosine derivative that plays a crucial role in gene expression and regulation. A noticeable reduction in 5-hmC levels has been observed during the progression of various malignant tumors, making it a key epigenetic biomarker for tumorigenesis. Although numerous analytical techniques, such as bisulfite sequencing, mass spectrometry, and chromatography, have been developed for 5-hmC detection, nanoparticle-based biosensors have attracted increasing attention because of their superior sensitivity, specificity, and efficiency. Nanoengineered optical and electrochemical biosensors arise as an avant-garde solution, offering high detecting performance, and an accurate and rapid 5-hmC monitoring, which is attractive for the POCT. Optical biosensors leverage interactions between light and biomolecules for real-time, label-free detection, while electrochemical biosensors are noted for their portability, low cost, and high sensitivity. Herein, this review core presents and discusses the current progresses in optical/electrochemical 5-hmC biosensing for the first time, considering engineered nanomaterials, optical/electrochemical transduction principle and biorecognition methodologies. Furthermore, it addresses the current challenges and limitations of these technologies and explores potential future directions for their development.