Porous silicon- and silica-based nanomaterials as smart nano-platforms for development of biosensors: Recent advances, challenges and future aspects

Porous silica/silicon (PSi) and mesoporous silica nanoparticles (MSNs) have arisen as optimistic nanomaterials for biosensing owing to their customizable honeycomb structures, large surface areas, and adaptable surface chemistries. They possess the ability to entrap a wide array of target substances, opening newer gates in the field of biosensors. This review directly addresses how innovations in PSi/MSN biosensor design and fabrication are advancing the field, addressing the knowledge gaps that exist, and providing probable resolutions to mitigate them. Despite the remarkable features of these particles, there are certain challenges, such as large-scale production, stability, risk of cross-interference, generation of false signals and background noise, and producing uniform biosensing structures. While the tunable pores offer entrapment of a large variety of molecules, they also induce steric hindrance. This review enlists hypotheses to overcome these difficulties, paving the way towards the generation of a broad range of biosensors, utilising the porous architecture of the nanomaterials. How these nanoplatforms are deployed for the rapid detection of pathogenic bacteria, viruses, and fungi, as well as for clinical biomarker detection, is elaborated. It emphasises advances, such as amplification-free, label-free electrochemical detection of microbial genetic material at picomolar concentrations. Prospective strategies with respect to the detection of micro- and nano-plastics, volatile organic compounds, developing self-healing multifunctional robotics and electronics, creating multiplexed wearable sensors, and designing smart therapeutic platforms are outlined. This article is a systematic combination of applications, recent progress, challenges, research gaps, probable strategies to be adapted, and future potential of biosensors based on PSi/MSN.