# Nanomaterials for Healthcare Biosensing Applications
## 3 Applications of Inorganic Nanomaterials in Healthcare Biosensing
### Magnetic Nanoparticles
Wavelength modulated SPR provided responses from 1.25 ng mL\({}^{-1}\) to 4 ug mL\({}^{-1}\) of cTnI. Another study dispersed sodium oleate (NaOL) treated MNPs functionalised with cAb in water for the extraction of cTnI for further sensing on a gold nanorod (GNR)-based LSPR chip [183]. The NaCl treatment generated carboxyl groups on the MNP surface, encouraging cAb attachment. The fluorescent properties of Fe\({}_{3}\)O\({}_{4}\) in addition to its high surface area contributed to an LOD of 2.5 ng mL\({}^{-1}\). The applications of MNPs are not restricted to merely electrochemical and optical sensors, but also include piezoelectric and magnetic sensors. Human \(\alpha\) thrombin (H\(\alpha\)T) is a biomarker for cardiovascular diseases and pulmonary metastasis. Sinha et al. reported H\(\alpha\)T detection using a planar Hall magnetoresistive (PHR) sensor [184]. They used an Au film conjugated with thiolated DNAaptamer as the sensing platform and developed a sandwich immunoassay with biotinylated aptamer in the presence of the H\(\alpha\)T analyte. Finally, streptavidin-coated MNPs were used to report a magnetic signal between 86 pM and 8.6 uM and a lower detection limit of 86 pM was achieved. Bayramoglu et al. reported a similar aptasensor for H\(\alpha\)T based on piezoelectric transduction by a gold QCM [185]. Fe\({}^{+2}\) and Fe\({}^{+3}\) nanoparticles were suspended in poly(2-hydroxyethyl methacrylate-ethylene glycol dimethacrylate-vinylene carbonate) Mp(HEMAEGDMA-VC) microbeads and the microbeads were functionalised with thrombin binding aptamer (TBA). The QCM chip in this case was treated with Cys before TBA immobilisation to encourage glutaraldehyde coupling. The piezoelectric sensor sensor could quantify H\(\alpha\)T in a linear range of 1.0-100 nM. MNPs are also a popular choice for pathogen detection. Takemura and co-workers developed an LSPR-magnetofluorommunoassay (MFIA) for the ultrasensitive detection of norovirus (NoV), a pathogen responsible for infectious gastrointestinal disease, using a multifunctional nanocomposite of gold nanoparticles, magnetic nanoparticles, and CdSe quantum dots, wherein anti-norovirus genogroup II antibody (antiNoV) conjugated the AuNP-MNP and the CdSeSQD [186]. The sensor could detect NoV-like particles (NoV-LP) in human faeces in a concentration range of 1.0 pg mL\({}^{-1}\)-5.0 ng mL\({}^{-1}\) with an LOD of 0.48 pg nL\({}^{-1}\). When tested for various types of clinical NoV, the LOD was 84 RNA copies mL\({}^{-1}\). Jeong and Lim developed a magnetophoretic separation inductively coupled plasma mass spectrometry (InCP-MS) technique employing multicore magnetic nanoparticles (MMNPs) for the sensitive detection of _Salmonella typhimurium_ (_S. typli_), a pathogen responsible for gastroenteritis [187]. In this technique, MMNPs were doped with Cesium (Cs), silanised, and treated with (3-Aminopropyl)trimethoxysilane (APTMS). The capture probe in this study consisted of gadolinium-doped silica nanoparticles with antibody immobilisation (Gd-SilNP-cAb). The LOD of this sandwich-type assay was found to be 102 cells mL\({}^{-1}\).