Controlled Surface PEGylation Of Single-Walled Carbon Nanotubes And Their Drug Loading And Release Properties

Single-walled carbon nanotubes (SWNTs) are novel one-dimensional nanomaterials, which could carryvarious cargoes into cells, such as drugs, peptide, proteins, plasmid DNA, and small interfering RNA(siRNA) via endocytosis for chemotherapy of cancer. Furthermore, the intrinsic near-infrared region (NIR)light absorption property of SWNTs has been utilized for physiotherapy of cancer. The efficacy of cancertherapy is expected to be promoted by a combination of chemotherapy and physiotherapy during cancertherapy. However, there are two important problems need to be solved, the first one is the short bloodcirculation time of SWNTs and their high uptake by the reticuloendothelial system (RES). Bescides,proteins will be rapidly adsorbed on SWNTs to form a protein layers on the surface of SWNTs in vivo,which results in a series of side effects such as hematolysis and thrombus. The other challenge is thecontrolled release of anticancer drugs at the tumor site, as well as increasing local drug concentration andreducing the side effects. In this paper, these works have been done aim to the problems mentioned above.1A series of SWNTs@POEGMA with different molecular chain lengths of poly(oligo(ethylene glycol)methacrylate)(POEGMA) were prepared by mussel inspired chemistry and surface-initiated atom transferradical polymerization (SI-ATRP). The pH-dependent protein resistance and controlled release of modeldrug were conducted and the results indicate that SWNTs@POEGMA obtained a good ability of proteinresistance comparing to pristine SWNTs and the protein resistance ability increased with the increasing ofPOEGMA length. Besides, the protein resistance ability decreased with the increasing of pH values. Theloading and release of rhodamine6G (Rh6G) indicate that the loading amount of Rh6G by pristine SWNTswas much higher than SWNTs@POEGMA, however, the release of Rh6G from SWNTs was just about25%, while it was nearly100%for SWNTs@POEGMA at pH=5.0. Further Raman analysis indicates thatthe method used in this paper is a nondestructive manner in modification of SWNTs.2Three copolymers with different lower critical solution temperature (LCST) composed of POEGMAand poly(2-(2-methoxyethoxy)ethyl methacrylate (PMEO2MA)) segments modified SWNTs(SWNTs@P(OEGMA-co-MEO2MA)) were prepared by a combination of mussel inspired chemistry andSI-ATRP. The P(OEGMA-co-MEO2MA) were retrived by alkaline etching method (1M NaOH) and theirLCSTs and molecule weights were measured. Raman analysis of the recycled SWNTs indicates that theintrinsic properties of SWNTs were promoted because of the reduction of SWNTs by Pdop and whichfurther proved that the method is really nondestructive. Lastly, the temperature-responsive loading andrelease of Rh6G by SWNTs@P(OEGMA-co-MEO2MA) were conducted, the results indicate that theloading and release of Rh6G by SWNTs@P(OEGMA-co-MEO2MA) were higher than that of thetemperature above the LCST.3With the turning of ethylene oxide (EO), three PEGylated SWNTs were successfully prepared byanionic ring-opening polymerization (LAROP) and the PEGylated SWNTs were characterized by a seriesof techniques. This work provides a novel method to prepare PEGyalted SWNTs.