ABSTRACT
In recent years, inefficiency of transfection and the lack of safe gene vectors have limited the feasibility of gene therapy. Fabrication of a vector that is safe and has high transfection efficiency is crucial for the development of successful gene therapies. Herein, we complexed chitosan to plasmids at various N/P ratios, the molar ratios of the amino groups of chitosan to the phosphate groups of DNA, to create chitosan-DNA nanoparticles (CDNs), and then measured CDNs size, zeta-potential, efficiency of plasmid complexation, and plasmid integrity from enzyme digestion. We also used flow cytometry and fluorescence microscopy to examine the effect of an ultrasound (US) regimen on the efficiency of transfection of HeLa cells. The results revealed that the average size, zeta-potential, and loading efficiency of plasmid DNA in CDNs were 180-200 nm, 26-35 mV, and greater than 80%, respectively. Moreover, the transgene expression could be enhanced efficiently while HeLa cells or tumor tissues were given CDNs and then treated with US. Therefore, the use of chitosan nanoparticles and an US regimen shows great promise as an effective method of gene therapy.
Subject(s)
Chitosan/chemistry , Gene Transfer Techniques , Nanoparticles/chemistry , Plasmids/chemistry , Sound , Chitosan/pharmacology , Gene Expression , HeLa Cells , Humans , Plasmids/pharmacology , TransgenesABSTRACT
Thermosensitive nanoparticles based on poly(N-isopropylacrylamide-co-((2-dimethylamino)ethylmethacrylate)) (poly(NIPA-co-DMAEMA)) copolymers were successfully fabricated by free radical polymerization. The lower critical solution temperature (LCST) of the synthesized nanoparticles was 41 °C and a temperature above which would cause the nanoparticles to undergo a volume phase transition from 140 to 100 nm, which could result in the expulsion of encapsulated drugs. Therefore, we used the poly(NIPA-co-DMAEMA) nanoparticles as a carrier for the controlled release of a hydrophobic anticancer agent, 7-ethyl-10-hydroxy-camptothecin (SN-38). The encapsulation efficiency and loading content of SN-38-loaded nanoparticles at an SN-38/poly(NIPA-co-DMAEMA) ratio of 1/10 (D/P = 1/10) were about 80% and 6.293%, respectively. Moreover, the release profile of SN-38-loaded nanoparticles revealed that the release rate at 42 °C (above LCST) was higher than that at 37 °C (below LCST), which demonstrated that the release of SN-38 could be controlled by increasing the temperature. The cytotoxicity of the SN-38-loaded poly(NIPA-co-DMAEMA) nanoparticles was investigated in human colon cancer cells (HT-29) to compare with the treatment of an anticancer drug, Irinotecan(®) (CPT-11). The antitumor efficacy evaluated in a C26 murine colon tumor model showed that the SN-38-loaded nanoparticles in combination with hyperthermia therapy efficiently suppressed tumor growth. The results indicate that these thermo-responsive nanoparticles are potential carriers for controlled drug delivery.
Subject(s)
Camptothecin/analogs & derivatives , Methacrylates/chemistry , Nanoparticles/chemistry , Nanotechnology/methods , Polymethacrylic Acids/chemistry , Temperature , Absorption/drug effects , Animals , Antineoplastic Agents/pharmacology , Camptothecin/pharmacology , Cell Death/drug effects , Delayed-Action Preparations , Endocytosis/drug effects , Female , Fluorescence , HT29 Cells , Humans , Irinotecan , Magnetic Resonance Spectroscopy , Mice , Mice, Inbred BALB C , Nanoparticles/ultrastructure , Particle Size , Static Electricity , ThermogravimetryABSTRACT
Polypropylene was successfully covalently grafted onto the surface of thermally reduced graphite oxide (PP-g-TRGO) by taking advantage of the "residual oxygen-containing functional groups" and the "grafting to" method. The PP-g-TRGO obtained showed an improved compatibility, and interfacial interaction, with an isotactic PP (iPP) matrix. The iPP/PP-g-TRGO nanocomposite exhibited a dramatically improved thermal stability compared to that of neat iPP even at low loadings.
Subject(s)
Crystallization/methods , Graphite/chemistry , Nanostructures/chemistry , Nanostructures/ultrastructure , Polypropylenes/chemistry , Macromolecular Substances/chemistry , Materials Testing , Molecular Conformation , Oxides/chemistry , Particle Size , Surface PropertiesABSTRACT
Colorectal cancer is one of the leading causes of cancer death and often goes undetected with current colonoscopy practices. Improved methods of detecting dysplasia and tumors during colonoscopy could significantly improve mortality. Herein, we report a high-performance nanoparticle for photodynamic detection of colorectal cancer, where alginate is physically complexed with folic acid-modified chitosan to form nanoparticles with improved drug release in the cellular lysosome. The incorporated alginate molecules could complex stably with chitosan via electrostatic attraction, and the z-average diameter and zeta-potential of the prepared nanoparticles (fCAN) was 115 nm and 22 mV, respectively, enough to keep the nanoparticles stable in aqueous suspension without aggregation. When loaded with 5-aminolevulinic acid (5-ALA; 27% loading efficiency), the nanoparticles (fCANA) displayed no differences in particle size or zeta-potential compared to fCAN. Moreover, the fCANA nanoparticles were readily taken up by colorectal cancer cells via folate receptor-mediated endocytosis. Subsequently, the loaded 5-ALA was release in the lysosome, and this was promoted by the reduced attraction intensity between chitosan and 5-ALA via the deprotonated alginate, resulting in a higher intracellular PpIX accumulation for the photodynamic detection. These studies demonstrate that the alginate incorporated and folic acid-conjugated chitosan nanoparticles are excellent vectors for colorectal-specific delivery of 5-ALA for fluorescent endoscopic detection.
Subject(s)
Alginates/chemistry , Chitosan/chemistry , Colorectal Neoplasms/diagnosis , Folic Acid/chemistry , Nanoparticles/chemistry , Photochemistry/methods , Animals , Biocompatible Materials/chemistry , Cell Line, Tumor , Drug Carriers/chemistry , Fluoresceins/metabolism , Glucuronic Acid/chemistry , Hexuronic Acids/chemistry , Humans , Intestinal Neoplasms/diagnosis , Materials Testing , Mice , Mice, Inbred C57BL , Models, MolecularABSTRACT
Folic acid can be covalently conjugated to chitosan molecules via its gamma-carboxyl moiety and thus retain a high affinity for colorectal cancer cells bearing folate receptor overexpression. Colorectal cancer is one of the leading causes of malignant death and often goes undetected with current colonoscopy practices. Improved methods of detecting dysplasia and tumors during colonoscopy will improve mortality. A folic acid conjugated chitosan nanoparticle as a suitable vehicle for carrying 5-aminolaevulinic acid (5-ALA) is developed to enhance the detection of colorectal cancer cells in vivo after a short-term uptake period. Chitosan can be successfully conjugated with folic acid to produce folic acid-chitosan conjugate, which is then loaded with 5-ALA to create nanoparticles (fCNA). The loading efficiency of 5-ALA in fCNA particles and the z-average diameter were in the range 35-40% and 100 nm, respectively. The zeta-potential for fCNA was 20 mV, enough to keep the nanoparticle stable without aggregation. The fCNA is then incubated with HT29 and Caco-2 colorectal cancer cell lines overexpressing folate receptor on the surface of the cell membrane to determine the rate of accumulation of protoporphyrin IX (PpIX). The results show that fCNA can be taken up more easily by HT29 and Caco-2 cell lines after short-term uptake period, most likely via receptor-mediated endocytosis, and the PpIX accumulates in cancer cells as a function of the folate receptor expression and the folic acid modification. Therefore, the folic acid-chitosan conjugate appears to be an ideal vector for colorectal-specific delivery of 5-ALA for fluorescent endoscopic detection.
