Conjugation of insulin onto the sidewalls of single-walled carbon nanotubes through functionalization and diimide-activated amidation

Chee Meng Ng,1 Hwei-San Loh,2 Kasturi Muthoosamy,1 Nanthini Sridewi,3 Sivakumar Manickam1 1Manufacturing and Industrial Processes Research Division, Faculty of Engineering, 2Faculty of Science, School of Biosciences, University of Nottingham Malaysia Campus, Semenyih, Selangor, 3Faculty of Science and Defence Technology, National Defence University of Malaysia, Kuala Lumpur, Malaysia Purpose: The high aspect ratio of carbon nanotubes (CNTs) allows the attachment of compounds that enhance the functionality of the drug vehicle. Considering this, use of CNTs as a multifunctional insulin carrier may be an interesting prospect to explore.Materials and methods: The carboxylic acid groups were functionalized on the sidewalls of single-walled CNTs (SWCNTs) followed by diimidation to form amide bonds with the amine groups of the insulin.Results: Scanning transmission electron microscopy and transmission electron microscopy establish clear conjugation of insulin onto the surface of nanotube sidewalls. The incorporation of insulin further increased the solubility of SWCNTs in biological solution for the tested period of 5 months. Bicinchoninic acid assay confirms that 0.42 mg of insulin could be attached to every 1 mg of carboxylated SWCNTs.Conclusion: With the successful conjugation of insulin to SWCNTs, it opens up the potential use of SWCNTs as an insulin carrier which in need of further biological studies.Keywords: diimidation, CNT, SWCNT, increased solubility, carboxylation, drug carrier&nbsp

Site-selective azide incorporation into endogenous RNase A via a "chemistry" approach

10.1039/c2ob26561cOrganic and Biomolecular Chemistry112353-361OBCR

Exceedingly biocompatible and thin-layered reduced graphene oxide nanosheets using an eco-friendly mushroom extract strategy

Kasturi Muthoosamy,1 Renu Geetha Bai,1 Ibrahim Babangida Abubakar,2 Surya Mudavasseril Sudheer,1 Hong Ngee Lim,3 Hwei-San Loh,2,4 Nay Ming Huang,5 Chin Hua Chia,6 Sivakumar Manickam1 1Manufacturing and Industrial Processes Research Division, Faculty of Engineering, 2School of Biosciences, Faculty of Science, University of Nottingham Malaysia Campus, Semenyih, Selangor, Malaysia; 3Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; 4Biotechnology Research Centre, University of Nottingham Malaysia Campus, Semenyih, Selangor, Malaysia; 5Low Dimension Materials Research Centre, Department of Physics, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia; 6School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia Purpose: A simple, one-pot strategy was used to synthesize reduced graphene oxide (RGO) nanosheets by utilizing an easily available over-the-counter medicinal and edible mushroom, Ganoderma lucidum. Methods: The mushroom was boiled in hot water to liberate the polysaccharides, the extract of which was then used directly for the reduction of graphene oxide. The abundance of polysaccharides present in the mushroom serves as a good reducing agent. The proposed strategy evades the use of harmful and expensive chemicals and avoids the typical tedious reaction methods. Results: More importantly, the mushroom extract can be easily separated from the product without generating any residual byproducts and can be reused at least three times with good conversion efficiency (75%). It was readily dispersible in water without the need of ultrasonication or any surfactants; whereas 5 minutes of ultrasonication with various solvents produced RGO which was stable for the tested period of 1 year. Based on electrochemical measurements, the followed method did not jeopardize RGO’s electrical conductivity. Moreover, the obtained RGO was highly biocompatible to not only colon (HT-29) and brain (U87MG) cancer cells, but was also viable towards normal cells (MRC-5). Conclusion: Besides being eco-friendly, this mushroom based approach is easily scalable and demonstrates remarkable RGO stability and biocompatibility, even without any form of functionalization. Keywords: extraction, Ganoderma, RGO, ultrasoun