# Quantum Leap from Gold and Silver to Aluminum Nanoplasmonics for Enhanced Biomedical Applications
## 3 Applications
### Plasmonic Medicine  
#### 3.2.1 Plasmonic Cancer Diagnosis and Treatment  
Current major cancer treatments involve chemotherapy, radiation, immunotherapy, and surgical resection [131; 132; 133]. In addition to the commonly used anticancer drugs [134], new, potent proteasome inhibitors designed to trigger cell death in tumorigenic cells have been used [135]. Radiation therapy has recently advanced, delivering direct, topography-based radiation to patients even through skull or spinal bones [136]. Minimally invasive surgery as well as endoscopic resection has been employed to treat patients with less side-effects than their traditional counterparts [137; 138]. Despite this progress, there is still a need for alternative therapies [139]. For example, chemotherapy, in addition to being cytotoxic, can induce tumor growth and support its spread throughout the body [140]. New therapies based on photosensizers and NPs have been developed [141; 142; 143; 144]. The benefits of nanotechnology have been applied to healthcare, advancing the nanomedical applications [145; 146]. Au NPs have found many applications in cancer treatment due to their high accumulation rates as well as surface chemistry that is amenable to molecular attachments [147; 148; 149]. Many different morphologies, including nanospheres, nanorods, nanoshells, nanocages, and triangular nanoprisms, were investigated [150; 151; 152; 153; 154; 155; 156; 157; 158]. Integration of the in vivo SERS imaging and PTT using Au NPs has been reported [157; 158]. SERS imaging with Au and Ag NPs has been used for cancer detection [159], with the potential promise of high sensitivity of biosensing down to femtomolar concentrations [160]. In addition to the enhanced sensitivity, SERS molecular fingerprints permit excellent multiplexing potentials due to the narrow spectral width of Raman peaks [161; 162]. Additional advantages of SERS include the ability to use a single excitation source for multiple probes, reduced photobleaching, and minimal background signal from water [163]. SERS also allows for the possibility of monitoring more than one biomarker at a time, as was shown by the improved accuracy of lung cancer diagnostics using functionalized hollow Au nanospheres [164]. SERS imaging enhanced the reproducibility of point-based analysis [165]. The development of Au nano-popcorn SERS probes that integrate selective cell targeting has led to localized heating, and selective cancer cell damage [166]. Optamers and SERS nanotag reporters can be co-anchored on the surface of Au NPs, leading to precise cancer detection and efficient treatment [167]. SERS nanotags on hollow Au nanospheres showed negligible cytotoxicity and recognized MCF-7 cells with high specificity and selectivity [168]. Al plasmonic substrates for SERS-based cancer diagnosis were fabricated using femtosecond laser ablation [169]. This resulted in wrinkled Al NSs, which showed strong molecular SERS signals from crystal violet and cysteine and were used for in vitro cancer detection. Photodynamic therapy (PDT) also benefits from Au NPs to increase the photosensizer efficiency for cancer treatment [170; 171; 172; 173] and wound healing [174]. Several challenges for NP-based phototherapy include passive accumulation of NPs [175], limited accessibility of NIR light [176], and biodegradability [177]. Al NPs are promising candidates to address these issues due to their broad spectral response and unique chemical properties. Hot electron generation mechanism (HET), described above, plays an important role in plasmonic phototherapy. For example, femtosecond transient absorption spectroscopy studies revealed the dynamics of temperature evolution and photo-induced HE generation in Au NPs [178]. The interplay of high temperature and HE effects could provide an improved synergistic cancer treatment. A combination of carbon nanotubes (CNTs) and Ag NPs have shown an advancement in PTT using hot electrons [179]. Hot electrons generated in Au NPs were used in biomedical applications.