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Afreen, Sadia (2018) Ultrasonic dispersal of buckminster fullerene [c60] leads to the formation of [8-hydroxy]fullerenol : synthesis and application. PhD thesis, University of Nottingham.

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Abstract

This thesis is focused on investigating the possibility of synthesizing polyhydroxylated fullerene/fullerenol from the ultrasonic dispersal of Buckminster fullerene (C60). Interestingly, ultrasonic dispersion of fullerene may result into potential fullerenol moieties, the prospect of which has long been overlooked to date and unnoted by others, hence it lacks quantitative analysis in explaining the possibility. On this context, based on some of the established facts, this thesis is going to evidence the possibility that when pristine fullerene is dispersed in an aqueous medium by ultrasonication, the acoustic cavitation resulting from sonication orchestrates the hydroxylation of fullerene to fullerenol moieties instead of hydration of fullerene molecules in the aqueous medium. This thesis deals with the above-raised possibility with a series of analytical studies and quantitative analysis which ultimately has proven that potential fullerenol moieties could be synthesized by the technique of ultrasonication, and this thesis is first to report that the most possible molecular structure of the potential fullerenol to be synthesized is C60(OH)8.2H2O with a yield up to 4.0%.

The formation of fullerenol and the possible molecular structure of the synthesized fullerenol was confirmed by FTIR analysis and TGA. A clear broad peak at 3395 cm-1 of -OH group coupled with other supporting bond stretching of C=C, C-O-H and C-O at 1625, 1427 and 1057 cm-1 respectively confirmed the formation of hydroxylated C60. The molecular weight calculation based on the percentage of C (82.6 %) and O (17.2%) obtained from FESEM analysis as well as the percentage of C (80.52 wt%) and H (0.96%) obtained from CHN elemental analysis, has proven that the fullerene was hydroxylated with eight -OH groups. TGA result showed 5.58 wt% degradation of the synthesized fullerenol from room temperature up to 100 oC which could be attributed to two molecules of water associated to the synthesized fullerenol moiety. Upon quantification, based on the data obtained from FTIR, FESEM, elemental analysis and TGA, the most possible structure of the synthesized fullerenol was found to be C60(OH)8.2H2O. The synthesized C60(OH)8.2H2O was found to be soluble both in water and DMSO at a concentration of ~0.33 mg/mL. In addition, AFM image as well as DLS analysis of the C60(OH)8.2H2O solution in DMSO showed that the particle size of C60(OH)8.2H2O synthesized by the ultrasound-assisted technique was within a range of 135-155 nm.

The next part of this thesis will be focusing on the potential application of the synthesized fullerenol, [C60(OH)8.2H2O], in preparing a folic acid-based electrochemical biosensor for the detection of a cancer biomarker folate receptor alpha. Fullerenols containing a different number of hydroxy groups derived via other organic synthesis techniques have previously been used in detecting cancer biomarker. Based on that scope, in this thesis it was investigated whether fullerenol, [C60(OH)8.2H2O], synthesized by the proposed method of ultrasonication can perform as a suitable nano-mediator in fabricating a biosensor for the detection of a cancer biomarker folate receptor alpha, which will provide some guidelines for others working in the similar area or related fields of science. Current studies, presented in this thesis show that a biosensor prepared by a simple combination of folic acid and the synthesized C60(OH)8.2H2O can detect folate receptor alpha up to 1 nM at a sensitivity of 3 µA/nM.cm2, where the stability and the reproducibility of the biosensor were 93% and 86% respectively.

Moreover, developing an electrochemical biosensor using a different combination of analytes, ligands, electrodes and electrolytes always comes with new challenges and this thesis also reports on the research investigations into those most important facts and factors to be associated with designing a folate receptor biosensor in presence of the synthesized fullerenol and folic acid as well as has attempted to provide some useful insights on how to deal with the issues that one might come across while designing and developing a biosensor to target folate receptor alpha with a combination of folic acid and fullerenol. On this ground, there are always some rooms for future studies and at the end of this thesis a potential idea of a ‘facile bioconjugation’ between folic acid and reference fullerenols [C60(OH)10.5H2O, C60(OH)36.8H2O, C60(OH)44.8H2O] has been proposed in providing some directions toward overcoming the existing issues related to developing folic acid-fullerenol based electrochemical biosensor for the detection of folate receptor alpha.

Item Type:	Thesis (University of Nottingham only) (PhD)
Supervisors:	Manickam, Sivakumar Muthoosamy, Kasturi
Keywords:	fullerene, ultrasonication, biosensor, nanomaterial, folate receptor
Subjects:	Q Science > QD Chemistry
Faculties/Schools:	University of Nottingham, Malaysia > Faculty of Science and Engineering — Engineering > Department of Chemical and Environmental Engineering
Item ID:	48760
Depositing User:	AFREEN, SADIA
Date Deposited:	22 Apr 2020 13:28
Last Modified:	06 May 2020 08:31
URI:	https://eprints.nottingham.ac.uk/id/eprint/48760

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