Improvement of Permeability of Poly(vinyl alcohol) Hydrogel by Using Poly(ethylene glycol) as Porogen

The porous structure of PVA hydrogel achieved with varying content and varying molecular weight of PEG was investigated. It was found that with increasing content or molecular weight of PEG, the diffusion coefficient D _e and UV transmission of ink solution increased, indicating that the permeability and mass transfer capability of the gel beads were enhanced. The swelling rate constant k and equilibrium swelling rate of the gel were significantly improved by addition of PEG, and many pores formed inside the gel to provide channels for microbial metabolites. With increasing molecular weight of PEG, the size of pores became increasingly large.     

识别金属离子客体的荧光传感开关的研究进展

分子识别是超分子化学的核心概念，荧光开关PET（photoinduced electron transfer)体系又是分子识别中的重要组成部分，是超分子化学与光化学学科相结合的成就，荧光开关作为一种全新的客体识别和分析手段，由于其独特的应用价值，近10年来正以惊人的速度在向前发展。     

Magnetic N-succinyl chitosan/alginate beads for carbamazepine delivery

Context: Epilepsy is a chronic condition characterized by recurrent unprovoked seizures. The most optimal use of drugs was limited due to their widespread systemic and central side effects. In contrast, focal drug delivery to epileptogenic focus based on superparamagnetic carrier is considered to be a promising and safe alternative. This delivery system could arrive exactly at the targeted tissue and deliver the loaded drug there with the help of an external magnetic field. Objective: A new magnetic delivery system was established to inhibit paradoxical discharge once the onset of seizures. Materials and methods: Carbamazepine was incorporated into N-succinyl chitosan (NSC)/alginate hydrogel beads by ionic interaction. The characteristics of the beads including morphology, release behavior, and magnetic property were also investigated. Results: Acceptable spherical morphology, excellent slow-release property, and superparamagnetic property of the NSC/alginate hydrogel beads were observed. Discussion and conclusion: The magnetic NSC/alginate beads may be acted as a sustained-release formulation. The drugs exhibit the potential magnetic property owing to Fe3O4 particles. It is promising that the released drugs are induced by the weak magnetic field of epileptogenic zone and have the potential of locating them so as to inhibit paradoxical discharge once the onset of seizures.     

Book Review

Triboelectrification affects particle adhesion and agglomeration and hence the formulation, manufacture, and use of dry powder inhaler (DPI) devices. Electrostatic charge measurement of two component mixes of spray-dried or crystalline lactose fine particles (<10 μm) 0, 5, 10, 15, 20, and 30% w/w with spray-dried or crystalline lactose 63–90 μm, respectively, has been undertaken using a system incorporating pneumatic transport of the mixed powders to a stainless steel cyclone charging device. The magnitude of charge on the mixes was shown to decrease with increased fine particle content, and there was no significant difference in charge for each concentration between spray-dried and crystalline lactose. Both the variation of charge and powder adhesion to the cyclone surface increased with increase in fine particle content. The proportion of fine particles in carrier systems in DPIs may thus have an important role where triboelectrification is involved.     

Preparation and application of chiral recognizable thermosensitive polymers and hydrogels consisting of N-methacryloyl-s-phenylalanine methyl ester

Amphiphilic random copolymers, poly(R-HPMA-co-S-PAM) and poly(HPMA-co-S-PAM), were prepared by radical copolymerization of N-methacryloyl-(S)-phenylalanine methyl ester (S-PAM) and N-[(R)-2-hydroxypropyl]methacrylamide (R-HPMA) or N-(2-hydroxypropyl)methacrylamide (HPMA) with various molar ratios of R-HPMA (or HPMA) (m) to S-PAM (n). Either aqueous solution of poly(R-HPMA-co-S-PAM) with the molar ratio of m : n = 0.81 : 0.19 or poly(HPMA-co-S-PAM) with the molar ratio of m : n = 0.79 : 0.21 exhibited the lower critical solution temperature (LCST) at 16°C. The LCST in the presence of (S)-(−)-phenylalanine (S-Phe) shifted from 16 to 20°C and 18°C for poly(R-HPMA-co-S-PAM) and poly(HPMA-co-S-PAM), respectively, whereas the LCST did not shift in the presence of (R)-(+)-phenylalanine (R-Phe). Thermosensitive Gel(R-HPMA-co-S-PAM) and Gel(HPMA-co-S-PAM) were also prepared from radical copolymerization of S-PAM and R-HPMA or HPMA in the presence of N,N′-ethylenebisacrylamide (EBAAm) as a crosslinker. When the gels shrunk at 40°C, the release of dansyl-(R)-phenylalanine (Dans-R-Phe) from the gel in which loaded Dans-R-Phe occurred was more easily done than that of Dans-S-Phe from the gel that loaded Dans-S-Phe. Thus, these thermosensitive copolymers and gels were found to exhibit chiral recognition for phenylalanine derivatives. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 228–236, 2001     

丙烯酰胺类反相微乳液聚合研究及应用进展

分析总结了丙烯酰胺类反相微乳液聚合的基本理论和工艺方法,介绍了国内外聚丙烯酰胺类水凝胶微球在调剖堵水和驱油中的应用现状,指出了该研究领域存在的问题和当前的研究热点.     

Fluorescent Functionalized Mesoporous Silica for Radioactive Material Extraction

Mesoporous silica with covalently bound salicylic acid molecules incorporated in the structure was synthesized with a one-pot, co-condensation reaction at room temperature. The as-synthesized material has a large surface area, uniform particle size, and an ordered pore structure as determined by characterization with transmission electron microscopy, thermal gravimetric analysis, and infrared spectra, etc. Using the strong fluorescence and metal coordination capability of salicylic acid, functionalized mesoporous silica (FMS) was developed to track and extract radionuclide contaminants, such as uranyl [U(VI)] ions encountered in subsurface environments. Adsorption measurements showed a strong affinity of the FMS toward U(VI) with a K_d value of 10⁵ mL/g, which is four orders of magnitude higher than the adsorption of U(VI) onto most of the sediments in natural environments. The new materials have a potential for synergistic environmental monitoring and remediation of the radionuclide U(VI) from contaminated subsurface environments.     

Significant Characteristics of Medical-Grade Polymer Sheets and their Efficiency in Protecting Hydrogel Wound Dressings: A Soft Polymeric Biomaterial

Hydrogel dressings are soft biomaterials that need protection from external influences. Polymer sheets such as breathable film (BF) or breathable laminate (BL) were characterized in respect of water vapor transmission, water contact angle, microbial penetrability, and antimicrobial property to protect hydrogel dressings. The mechanical property and water retention ability of hydogels PVP-CMC and PVP-CMC-BA with and without BF and BL have been examined. Hydrogels covered with either BF or BL show better mechanical flexibility; however, their water retention capacity increases reasonably. The determined efficient properties of polymer sheets established that BF is better than BL as a protective sheet cover for hydrogel dressings.