Nanomaterials like nanowires, carbon nanotubes, quantum dots, and nanoparticles have breakthrough applications in various engineering domains including the various sensor applications in biomedical engineering. Because of its huge ratio of surface area to volume compared to the macro materials, it is widely used. In this chapter, the authors describe briefly the fabrication, the working principle, as well as the various applications like biomarker detection, RNA and virus detection, and drug discovery of these nanomaterials. Lastly, they briefly highlight its advancement which includes long-term stability, high ionic strength solvent, sensitivity, reusability, and self-powering. Nanowire is going to bring huge innovations in biomedical sensors in the upcoming days.
Top1. Introduction
Biomedical sensors with exceptional sensitivity hold the potential to revolutionize disease detection, increasing the likelihood of life-saving intervention during the early stages of illnesses. Take, for instance, breast cancer: when identified in its localized state, the five-year survival rate surpasses 90%, but plunges to around 20% once it progresses to an advanced stage (Etzioni et al., 2003). There remains a strong demand for highly sensitive biosensors dedicated to early cancer detection (Wulfkuhle et al., 2003). While extensive research has been conducted to enhance biomedical sensor sensitivity, recent strides in nanotechnology promise groundbreaking solutions in the field of biomedical sensing (Kim et al., 2016). Nanotechnology encompasses a wide range of scientific and engineering disciplines that explore materials and structures on a scale of approximately 100 nm or less (Patolsky et al., 2006). At this nanoscale, material properties are profoundly influenced by surface-to-volume ratios and quantum size effects, yielding properties distinctly different from those at the macroscopic level. The vast surface area-to-volume ratio at the nanoscale renders nanostructures extremely responsive to surface changes. The electron behavior within these nanostructures is constrained by quantization effects, giving rise to quantum size effects where the device's energy levels are size-dependent. Moreover, the reduced scale enhances the excited energy of semiconductors at their lowest state and the strength of volume-normalized oscillators (Wang et al., 1991), resulting in nanostructures with high energy conversion efficiency and relatively low thermal noise (Koo et al., 2015). This is particularly advantageous in the context of biomedical sensors, as biomolecules fall within the same size range as synthetic nanostructures, spanning from approximately 10 to 100 nm.
Biomedical sensors primarily serve to identify and characterize chemical and biological substances, with applications ranging from disease diagnosis to drug development. Employing nanomaterials such as nanowires, carbon nanotubes, and nanoparticles, these crucial tasks can be readily accomplished (Kurkina et al., 2012). For example, semiconductor crystalline nanoparticles have been employed to detect labeled disease markers and other biological entities (Ballou et al., 2004), while colloidal gold has found use in optical imaging and magnetic resonance (Perez et al., 2004). Semiconductor nanowires have made it feasible to electrically detect a variety of substances without the need for labels (Datta et al., 2023). These nanowires are crafted from semiconductor materials (Waidi et al., 2023), and their surfaces can be easily tailored to enhance sensitivity to chemical and biological species (Datta et al., 2023). On the other hand, carbon nanotubes, another potential option for biomedical sensors, are produced by blending semiconductor materials and metals, necessitating additional purification steps (Cui et al., 2003). Furthermore, the binding protocols for various analytes to nanotubes have not been thoroughly established (Datta et al., 2023) (Barua et al., 2018). Consequently, nanostructures constructed with nanowires emerge as the most suitable choice for biomedical sensors, offering high sensitivity, uniformity, reproducibility, and scalability through a relatively straightforward fabrication process (Kaushik et al., 2014). This study delves into the fundamental principles underpinning nanowire-based biomedical sensors and explores an array of applications in the realms of biology and medicine, expanding upon our previous work (Barua et al., 2020). The content in this review avoids duplicating the material found in our prior reports. Additionally, we delve into advances related to long-term stability, sensitivity in high-ionic-strength solvents, reusability, and self-powering capabilities, all of which hold significant promise in overcoming the present limitations associated with nanowire-based biomedical sensors.