Environmental stimuli-responsive microcapsules are getting more and more interests because of their potential applications in site-specific and time- and rate-programmed controlled-release. In this study, thermo-responsive microcapsules with linear grafted poly(N-isopropylacrylamide) (PNIPAM) gates on the inner pore surface were prepared, and the thermo-responsive controlled-release experiments were carried out. Interfacial polymerization was introduced to prepare polyamide porous microcapsules, and plasma-graft pore-filling polymerization was used to graft PNIPAM into the pore of the microcapsule membranes. The experimental results showed that PNIPAM-grafted microcapsules were featured with thermo-responsiveness due to the thermoresponsive swollen-shrunken property of PNIPAM chains grafted on the inner pore surface of the microcapsule membrane. At temperatures below the lower critical solution temperature (LCST), the linear grafted PNIPAM chains on the inner pore surface were in the swollen state, and the pores in the membrane were closed and the solute molecules were restrained to pass, as a result the release rate was low. In contrast, the grafted PNIPAM chains were in the shrunken state at temperatures above the LCST, and therefore the pores in the membrane were open, and a high release rate was the result.
Acrylic Resins ; chemistry ; Biocompatible Materials ; Capsules ; Delayed-Action Preparations ; Drug Carriers ; Drug Delivery Systems ; Humans ; Polymers ; Porosity ; Temperature

Aim To investigate the effect of SA on induction of ERK1/2 activity in rat pulmonary smooth muscle cells(PASMCs).Methods Western blot analysis was employed to identify the activation of ERK1/2 stimulated by SA at different time points and concentrations in cultured rat PASMCs.Results An unexpected observation showed that ERK1/2 phosphorylation was seen after treatment of SA for 2h at a high concentration(30 ?mol?L-1) but not at lower concentration(from 1 nmol?L-1 to 1 ?mol?L-1).Activation of ERK1/2 pathway could be inhibited by an ERK1/2 inhibitor PD98059 or a protein kinase A(PKA) activator isoproterenol.Conclusion Together,these results suggest that SA has a strong dual regulating effect upon ERK1/2 through PKC and/or PKA pathways in rat PASMCs.

Thermo-responsive intelligent membranes with linear grafted poly(N-isopropylacrylamide) (PNIPAM) gates on the inner pore surface were prepared, and experiments were carried out on the thermo-responsive gating characteristics. Plasma-graft pore-filling polymerization was used to graft PNIPAM into the pore of the porous flat membranes. The experimental results showed that PNIPAM-grafted PVDF (PNIPAM-g-PVDF) membranes were featured with thermo-responsiveness due to the thermo-responsive swollen-shrunken property of PNIPAM chains grafted on the inner pore surface of the membrane. At temperatures below the lower critical solution temperature (LCST), the linear grafted PNIPAM chains on the inner pore surface were in the swollen state, and the pores in the membrane were closed; in contrast, the grafted PNIPAM chains were in the shrunken state at temperatures above the LCST, and therefore the pores in the membrane were open. The LCST of the thermo-sensitive gates could be adjusted by adding acrylamide (AAM) in the N-isopropylacrylamide (NIPAM) monomer solution, the LCST of the poly(NIPAM-co-AAM) gates increased simply with the increase of the AAM fraction.
Acrylic Resins ; Drug Carriers ; Drug Delivery Systems ; instrumentation ; methods ; Humans ; Membranes, Artificial ; Porosity ; Temperature

Aim To test the contribution of 15-HETE on expression of KV1.5 channel under hypoxia condition,using CDC or NDGA to block 15-LO/15-HETE,and to observe the effect of hypoxia on KV1.5 channel protein,mRNA expressions in cultured rat pulmonary arterial smooth muscle cells(PASMCs)and pulmonary arterials(PAs).Methods Western blot,RT-PCR and 15-LO blockers,cinnamyl 3,4-dihydroxy-[alpha]-cyanocinnamate(CDC)or nordihydroguiairetic acid(NDGA)were used to identify the role of endogenous 15-HETE on expression of KV1.5 channel in cultured rat pulmonary arterial smooth muscle cells(PASMCs)and PAs.Results(1)The expressions of KV1.5 channel protein and mRNA in PASMCs and PAs preteated with CDC or NDGA greatly increased than those of PASMCs under hypoxia group.(2)Exogenous 15-HETE added to PASMCs pretreated with CDC or NDGA greatly decreased the expression of KV1.5 than that of adding PASMCs pretreated with CDC or NDGA under hypoxia condition.Conclusion The down-regulation of KV1.5 channel expression caused by hypoxia is through endogenous 15-HETE.

Environmental stimuli-sensitive biodegradable drug delivery systems are drawing more and more attentions because of their advantages such as smart properties, high efficiency and easy-to-handle properties. On the basis of a large quantity of references on this topic, a review has been made on the developments of the thermosensitive and pH-sensitive intelligent polymeric systems for drug delivery.
Biocompatible Materials ; chemistry ; pharmacology ; Biodegradation, Environmental ; Chitosan ; chemistry ; Delayed-Action Preparations ; Drug Delivery Systems ; Excipients ; chemistry ; Humans ; Polyethylene Glycols ; chemistry ; Polyglactin 910 ; chemistry

Marine-derived biopolymers are excellent raw materials for biomedical products due to their abundant resources, good biocompatibility, low cost and other unique functions. Marine-derived biomaterials become a major branch of biomedical industry and possess promising development prospects since the industry is in line with the trend of "green industry and low-carbon economy". Chitosan and alginates are the most commonly commercialized marine-derived biomaterials and have exhibited great potential in biomedical applications such as wound dressing, dental materials, antibacterial treatment, drug delivery and tissue engineering. This review focuses on the properties and applications of chitosan and alginates in biomedicine.