# Nanomaterials for Healthcare Biosensing Applications
## 3 Applications of Inorganic Nanomaterials in Healthcare Biosensing
### Nanocages, Nanoshells and Nanowires  
Nanocages (NCgs) constitute a new class of nanomaterials made up of noble metals with a hollow interior and porous walls (Figure 10a). Their size generally ranges from 10 to 150 nm. Since these nanoparticles are cube-shaped, their optical properties differ from spherical nanoparticles, allowing them to absorb light in the NIR region of electromagnetic spectrum. Depending on the extent of precursor added to the system, their degree of LSPR can be tuned. NCgs are used in biosensing due to their ability to absorb and scatter NIR light [2]. Mei et al. supported palladium copper nanocages \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Sensor Platform/Label** & **Analytic** & \begin{tabular}{c} **Detection** \\ **Mechanism** \\ \end{tabular} & \
\begin{tabular}{c} **Detection Range** \\ \end{tabular} & **LOD** & **Reference** \\ \hline carboxyIMN-Str-mAb/AuNF-urease-pAb & \(L\) _mmacyclogens_ & EIS & \(3\times 10^{2}\)-\(3\times 10^{4}\) cfu mL\({}^{-1}\) & 30 cfu mL\({}^{-1}\) & [204] \\ \hline \multirow{2}{*}{Au-IDE-thiourea-carboxyIANNF-mAb} & CEA & \multirow{2}{*}{Capacitance} & 2–1000 pg mL\({}^{-1}\) & 5 ps mL\({}^{-1}\) & \\  & hEGFR & & 20–1000 pg mL\({}^{-1}\) & 5 ps mL\({}^{-1}\) & \\  & CA 15-3 & & 10–100 U mL\({}^{-1}\) & 1 U mL\({}^{-1}\) & \\ \hline \hline \multirow{2}{*}{NH\({}_{2}\)-AgNP-CNT-GO-aptamer} & DA & DPV & 3–110 nM & 700 ± 19.23 pM & [205] \\ \hline Au-MCH-peptide-GO-AgNP & PSA & EIS, CV, LSV & 0.005–20 mg mL\({}^{-1}\) & 0.33 pg mL\({}^{-1}\) & [206] \\ \hline GCE/Cu\({}_{3}\)OSNs/Nafion & Glucose & Amperometry & 1.25–37.5 uM & 0.4 uM & [207] \\ \hline GCE-AuAuNSs & AA & LSV & 5 uM–2 mM & 2.2 uM & [208] \\ \hline GCE-CMG-Au NCgs & Hydrazine & Amperometry & 6–1600 uM & 0.5 uM & [209] \\ \hline GCE-SGN-PdPt NCgs & H\({}_{2}\)O\({}_{2}\) & Amperometry & 1–300 uM & 0.3 uM & [210] \\ \hline GCE-choline-Au NCg-MWCNT & GMP & CV, DPV & 0.3–600 uM & 0.1 uM & [211] \\ \hline Si SiN-anti-sOHdG & 8-OHdG & -i-v char & 35-411 nM & 3.5 nM & [212] \\ \hline Si-ZnO NWA-AuAgm-MFA-IZM & Ig & +v char & 5 \(\times 10^{2}\)-19 mg mL\({}^{-1}\) & 102.76 mg mL\({}^{-1}\) & [213] \\ \hline PPCE-ZnO NWA-GOx & Glucose & CA & 0.1–3.6 mM & 46 ± 31 uM & [214] \\ \hline \hline \end{tabular}
\begin{tabular}{c} Abbreviations: SOHDG: 8-hydroxydeoxyguanosine; AA: Ascorbic acid; anti-: Antibody of; CA: Chronoamperometry; CA 15-3: Cancer antigen 15-3; CEA: Carcinembryonicogenic antigen; CMG: Chemically modified graphene; CNT: Carbon nanotube; CV: Cyclic voltammetry; DA: Dopamine; DPV: Differential pulse voltammetry; EIS: Electrochemical impedance spectroscopy; GCE: Glassy carbon electrode; GO: Graphene oxide; GONG: Glucose oxidase; GMP: guanosine-5’-monophosphate; AuRuNNs: Hollow gold ruthenium nanoshells; hEGFR: Human epidermal growth factor receptor; IDE: Interdigital electrode; Ig: Immunoglobulin; i-v char: i-v characterisation; _L. monocytogenes: Listeria monocytogenes_; LSV: Linear sweep voltammetry; LZM: Lysozyme; mAb: Monoclonal antibody; MCH: Mercaptohexanol; MNP: Magnetic nanoparticles; MPA: 3-Mercaptopropionic acid; MWCNT: Multivwalled carbon nanotubes; NCgs: Nanocages; NP: Nanoparticles; NSNs: Nanoshells; NW: Nanowire; NWA: Nanowire array; pAb: Polyclonal antibody; PSA: Prostate specific antigen; SGN: SnO\({}_{2}\)-graphene nanosheets; Str: Streptavidin. \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Inorganic nanomaterial-based electrochemical biosensors. (PdCuNCgs) on RGO for CAT determination [153]. RGO prevents the agglomeration of the Pdu units during repeated catalysis. The RGO-PdCuNCgs acted as an immobilisation platform for increase enzyme. Due to the large surface area and high conductivity of PdCuNCgs, the electrochemical sensor was able to detect 5 uM-5.155 mM CAT with an LOD of 1.5 uM. Zhao and co-workers reported a facile fabrication of a peroxide mimetic glucose biosensor using iron nanoparticle loaded Cu3O4 hollow nanocage (FeNPs@Co3O4 HNCgs) [215]. The nanocages displayed 195 times higher affinity for H2O2 in comparison to HRP.