A Scoping Review of 20-100NM Gold Nanomaterials for Cancer Diagnosis

Abstract

Introduction: With 90% of current chemotherapeutic drugs failing during the metastasis stages of cancer, the early diagnosis and prognosis of tumours is vital for patients. We can now fine-tune nano-sensors to detect trace amounts of biomarkers present in blood to provide a cheaper, faster and less invasive alternative to traditional tissue biopsies. This literature review will focus on the employment of gold nanoparticles (AuNPs) as viable nano-sensors for cancer detection in the bloodstream, given their biocompatibility, NIR/visible light optical properties and functionalization.

Methods: To carry out the research for this review we used published, peer-reviewed articles from a variety of online reputable databases; mainly using the search terms ‘AuNP’, ‘SPR’ and ‘nano-sensors’; whilst specific effects mentioned within articles were independently searched for.

Results and Discussion: Circulating tumour DNA (ctDNA), exosomes and tumour miRNA (micro-RNA), obtained through liquid biopsies (LBs), can be used as effective biomarkers of cancer. By attaching complimentary oligonucleotides and optical sensors to the surfaces of AuNPs, usually via Au-thiol links, they can detect these biomarkers despite their low concentrations. There are many imaging techniques we can use to then quantify the formation of AuNP-biomarker formation. When fluorophore dyes are used, florescence will be observed since the binding of biomarkers will cause a conformational change to the AuNPs-aptamer-dye structure thus reduce the quenching properties that AuNP’s impose on dyes when in close proximity. Due to the optical properties of Au, such as their strong surface plasmon resonance (SPR) effects, they can be used to observe shifts in the absorbance characteristics to quantify AuNP-biomarker formation.

Conclusion: The tuneable optical properties of AuNP means we can gather real time information, using low energy EM waves. Modifying AuNP sensors to resonate within the NIR (near infrared) wavelengths of light will improve their ability to produce a strong detection signal even when inside patients, as the attenuation coefficients of biological tissues at these wavelengths are extremely low. Thus, decreasing diagnosis time and removing the need for samples to be sent to labs; as well as being safer than UV-X-ray wavelengths.