Abstract

Background: Cancer is a potentially fatal diagnosis, but due to modern medicine there is a potential cure in many of these cases. The rate of treatment success depends on early disease detection and timely, effective delivery of tumour specific treatment. There are many ongoing researches aimed to improve diagnostics or treatment, but the option to use both modalities concomitantly is deficient. In this project we are using the advances in nanotechnology to develop new theranostic tool using single walled carbon nanotubes (SWCNT) and Quantum dots (QDs) for early cancer cell detection, and option to deliver targeted treatment.

Method: SWCNTs were refluxed in HNO3/H2SO4 (1:3) at 120ºC for 120 minutes. Functionalised SWCNT was then covalently attached to octa-ammonium polyhedral oligomeric silsesquioxane (POSS), QDs and conjugated with antibodies for targeted cell detection. Fourier transforms infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), UV/NIR analysis, Raman and UV-VIS spectroscopy were used in order to prove the successful conjugation. Toxicology study using alamar blue analysis and DNA assay was conducted in order to choose the best concentration of SWCNT, octa-ammonium-POSS and QDs before commencing the conjugation process. Human colorectal cancer cell line HT29, pancreas cancer cell line PANC-1 and mouse fibroblasts 3T3 were then treated with or without antibody conjugated SWCNT-POSS-QDs (CPQ) compound solution. The cell response was observed under the microscope after 24, 48 and 72 hours.

Results: FTIR and Raman spectroscopies confirmed covalent binding of the SWCNTs to Octa-Ammonium-POSS. This was supported by TEM images and photos obtained, which showed well dispersed SWCNTs following its treatment with Octa-Ammonium-POSS compared to pristine SWCNT samples. UV-VIS graphs determined the presence of antibody within the compound. UV/NIR demonstrated QD fluorescence even after attachment of SWCNT-POSS. The cellular behaviour revealed high CPQ-antibody complex affinity towards cancer cells when compared to healthy cell line which internalised the complex only on day three. The pancreas cancer cell line had appearance of lysed pulp after 72 hours of incubation. Colonic cancer cells seemed to regain ability to populate from day three signifying that higher treatment payload is necessary.

Conclusion: We have successfully manufactured novel compound consisting of Octa-Ammonium-POSS linked SWCNTs, QDs, and tumour specific antibodies. The complex has proven its potential as cell probing tool, and the attachment of antibodies has shown high affinity to cancer cells rendering this an attractive model for further theranostic developments.

Keywords: Carbon nanotubes, quantum dots, octa-ammonium polyhedral oligomeric silsesquioxane, cancer antibodies, colon cancer, pancreas cancer, theranostics.