A Path Towards Conquering Cancer

Despite the significant scientific advancements devised to decrease death, reduce discomfort, and improve quality of life for cancer patients, there remains a distinct deficiency in the competencies of cancer-based therapeutic technologies. The burden of cancer has continually progressed; by 2040, cancer-related death will have increased by 42% from 2018, making it a leading cause of death worldwide (National Cancer Institute, 2020). Against this grim backdrop emanates nanotechnology, a modern cancer-treating strategy that encourages the idea that through further research, we can improve diagnosis and mitigate mortality (Heath and Davis, 2013).

Conventional technology for cancer therapy is suboptimal; treatments such as radiation therapy and chemotherapy are costly, insufficient for drug-delivery, and limited in tracking organ or tissue metastases (Bhandare and Narayana, 2014). However, recent advances in the mobility, detainment, and surface properties of nanotechnology have introduced us to the previously unexplored chemical characteristics of cancer, enabling researchers to increase efficacy for drug-delivery and expand functional capabilities for concurrent imaging techniques (Bhandare and Narayana, 2014). 

Nanotechnology is defined as the science and engineering of devices and materials whose smallest functional organization, in at least one dimension, is on the nanometer scale or one billionth of a meter (Saini, Saini and Sharma, 2010). By operating at submolecular levels, researchers can gain unique insights into the broad spectrum of applications in cancer treatment, including areas such as therapeutics and diagnostics (Bhandare and Narayana, 2014). 

A leading anticancer application of nanomaterials at the molecular level involves Gold Nanoparticles (AuNPs) (Jin, et al., 2020). Due to its small atomic radius and high atomic number, gold is the prevailing substance used to increase contrast between structures in the body for medical imaging (Jin, et al., 2020). Studies reveal that the Enhanced Permeability and Retention (EPR) effect provides the basis for the aggregation of AuNPs onto diseased sites. (Dreaden, et al., 2013; Jin, et al., 2020). Due to rapid tumour growth, internal blood vessels become deficient, allowing AuNPs of certain sizes to permeate through tumour vessels and form clusters for clearer diagnosis (Jin, et al., 2020). This diffusivity of AuNPs through large vascular pores is called the EPR effect, a technique that is critical for passive targeting of AuNPs for enhanced imaging (Dreaden, et al., 2013). 

Clinicians may also employ active targeting for gold immobilization (Rao, et al., 2019). By applying an intermediate layer of functional groups—such as amine or thiol—onto cancerous cells consisting of an organic molecule, AuNPs are able to attach with considerably higher efficacy. By adjusting pH to allow for protonation, gold’s affinity for amine is increased, and the negatively charged AuNPs readily interact with the amine through electrostatic interaction (Rao, et al., 2019). Alternatively, thiol groups may be utilized for their strong covalent bond with gold surfaces (Rao, et al., 2019). These connection layers containing functional groups ensure the interaction between AuNPs and the cancer cells is strong and stable for relatively long durations (Rao, et al., 2019). The addition of specific ligands allows delivery of drug-encapsulated AuNPs to uniquely identify cells or subcellular sites, thereby reducing the damaging effects of systemic exposure of the cytotoxic drug (Bazak, et al., 2014). These active and passive actions, depicted in Figure 1, have immediate relevance for the imaging and drug-delivery requirements for cancer treatment (Jin, et al., 2020).

Figure 1: Model illustrating passive and active targeting of AuNPs to specific cancer cells. Here, various morphologies of AuNPs accumulate to cancer cells through an osmotic effect (passive targeting) or receptor binding effect (active targeting). The top half of this image illustrates passive targeting, a process in which AuNPs gather onto cancerous cells through increased permeability of defective blood vessels. This allows for better tumour therapy and imaging. The bottom half of this image delineates active targeting, which occurs through covalent or electrostatic interactions (Jin, et al., 2020).   

By advancing our current understanding of nanotechnology, we are presented with the potential to markedly improve the current modalities of cancer treatment and diagnosis. The future of cancer imaging, diagnosis, and drug-delivery remains firmly ensconced within the future of nanotechnology. With further research, we can develop novel approaches to cancer and effectively ward off one of the leading causes of death in the 21st century. 

References:

Bazak, R., Houri, M., El Achy, S., Kamel, S. and Refaat, T., 2014. Cancer active targeting by nanoparticles: a comprehensive review of literature. J Cancer Res Clin Oncol, 141(5), pp.769–784.

Bhandare, N. and Narayana, A., 2014. Applications of Nanotechnology in Cancer: A Literature Review of Imaging and Treatment. Journal of Nuclear Medicine & Radiation Therapy, 5(4), pp.1–9. 

Dreaden, E.C., Austin, L.A., Mackey, M.A. and El-Sayed, M.A., 2013. Size matters: gold nanoparticles in targeted cancer drug delivery. Ther Deliv, 3(4), pp.457–458.

Heath, J.R. and Davis, M.E., 2013. Nanotechnology and Cancer. Annu Rev Med, 59, pp.251–265. 

Jin, C., Wang, K., Oppong-Gyebi, A. and Hu, J., 2020. Application of Nanotechnology in Cancer Diagnosis and Therapy – A Mini-Review. Int J Med Sci, 17(18), pp.2964–2973. 

National Cancer Institute, 2020. Cancer Statistics. [online] Available at: <https://www.cancer.gov/aboutcancer/understanding/statistics#:~:text=Cancer%20is%20among%20the%20leading,related%20deaths%20to%2016.4%20million.> [Accessed 22 Mar. 2021].

Rao, X., Tatoulian, M., Guyon, C., Ognier, S., Chu, C. and Hassan, A.A., 2019. A Comparison Study of Functional Groups (Amine vs. Thiol) for Immobilizing AuNPs on Zeolite Surface. 9(7), p.1034. Saini, R., Saini, S. and Sharma, S., 2010. Nanotechnology: The Future of Medicine. J Cutan Aesthet Surg, 3(1), pp.32–33.