Résumé
In recent years, layer-by-layer self-assembly (LbL) has developed rapidly. It has been widely used in various industries such as medicine and metallurgy because of its simplicity, flexibility and controllability. In the study of drug delivery system, hollow microcapsules constructed by LbL method as drug carrier have great advantages in drug release, circulation in vivo and bioavailability, providing a technical platform for targeted drug release. In this paper, we summarize the types of film-forming materials and the driving force used in LbL technology, the way of loading drug into hollow micro capsule, and the variety of loaded drugs. We focus on the release mechanism, its evaluation and safety evaluation of self-assembled film as drug carrier in vivo and in vitro. The review shows the great application prospect of LbL technology in the field of drug delivery.
Résumé
Objective To fabricate the asiaticoside loaded capsosomes with CaCO3 as core (CASI) and establish the method for determination of entrapment efficiency, then the prescription of formulation and preparation process were screened with the entrapment efficiency as index. Methods An HPLC method was established to determine the contents of asiaticoside. CASI were prepared by co-precipitation method and layer-by-layer assembly technique. The encapsulation efficiency was determined by a proved centrifugation. In this study, the effect of concentrations of capsule material, pH and rotating speed on encapsulation efficiency was investigated. Results The encapsulation efficiency obtained by centrifugation was accurate and reliable. The optimized prescription was concentrations of 1 mg/mL capsule material with pH value 12, pH 7.9 of liposomes, two precursor layers, one liposome layer, rotating speed 500 r/min, and 15 min of reaction time. The CLSM images confirmed the structural integrity of the CASI. Conclusion This formulation endowed with high encapsulation efficiency, and the CASI observed by CLSM turned out to be globular shapes and was narrow in size distribution.
Résumé
A highly stable multilayer film modified glassy carbon electrode (GCE) containing polydopamine (PDA) and Cu microparticles was fabricated by layer-by-layer self-assembly technique. The fabrication process was based on the self-polymerization of dopamine and electroless deposition of Cu microparticles on PDA coating. The fabrication process of multilayer films was characterized by UV-Vis spectra. The electrochemical performance of GCE / (PDA/ Cu) n modified electrode for glucose detection was investigated by cyclic voltammetry and amperometric current-time curve under alkaline conditions. At detection potential of 0. 35 V, the GCE / ( PDA/ Cu) 4 modified electrode presented a linear range of 0. 5 - 9. 0 mmol/ L with a detection limit of 5. 8 μmol/ L (S / N=3). Moreover, the sensitivity of the modified electrode was tunable by controlling the number of bilayers of the multilayer films. The modified electrode showed highly selective, stable and fast amperometric sensing of glucose. It was applied to determine glucose in human blood serum with satisfactory results.
Résumé
Objective To construct a sirolimus loaded drug-eluting stent (DES) using chitosan/heparin coating membrane and to explore its effect on anticoagulation and early re-endothelialization in porcine coronary artery. Methods Chitosan/heparin layer-by-layer self-assembly coating was applied to sirolimus DES, and the asymmetric applicator was used to allow for the stent blood surface to be chitosan/heparin coated and the stent vascular surface to be polylactic acid (PLA)--irolimus. The experiment was divided into bare metal stent (BMS) group, chitosan/heparin stent group, sirolimus DES group and chitosan/heparin sirolimus DES group. The anticoagulation effect of chitosan/heparin sirolimus DES was tested by arteriovenous shunt model and high load thrombosis model. The effect of chitosan/heparin sirolimus DES on early re-endothelialization was tested by 1-week long balloon injury to porcine coronary artery. Results No thrombus was found on the surfaces of chitosan/heparin sirolimus DES and chitosan/heparin stent in the arteriovenous shunt model, while the surfaces of BMS and sirolimus DES were covered with thrombus. No stent thrombosiswas found in the high load thrombosis model test of chitosan/heparin sirolimusDES and chitosan/heparin stent within 6 hours, and stent thrombosis was found in BMS at (59. 0±8. 5) min and in sirolimus DES at (67. 0 ±7. 8) min (P<0. 01). Theearly re-endothelialization test showed endothelial coverage rates of chitosan/heparin sirolimus DES and chitosan/heparin stent after 7 d implantation were (82. 7± 16. 4) % and (80. 7 ± 14. 1) %, significantly higher than those of BMS and sirolimus DES ([64. 3±11]% and [59. 8±8. 4]%, respectively; P<0. 01). Conclusion Chitosan/ heparin-coated-sirolimus DES has satisfactory anticoagulation property and it can accelerate early re-endothelialization.