Variations in polyethylene glycol brands and their influence on the preparation process of hydrogel microspheres

Hydrogel microspheres, e.g. for the use as protein carriers, can be prepared without the use of organic solvents via an emulsified aqueous two-phase system (ATPS) that is based on two immiscible polymer solutions. The type and concentration of the polymers can affect the ATPS and finally the distribution of incorporated drugs between the aqueous phases. For the preparation of hydrogel microspheres based on hydroxyethyl starch–hydroxyethyl methacrylate (HES–HEMA), hydroxyethyl starch–methacrylate (HES–MA), and hydroxyethyl starch–polyethylene glycol methacrylate (HES–P(EG)₆MA), polyethylene glycol 12,000 (PEG 12,000) was used as second polymer. The particle size distribution and encapsulation efficiency of the microspheres depended dramatically on the type of PEG 12,000 that was used in the second phase of the ATPS. Analysis of different PEG 12,000 brands by various methods revealed differences in the salt composition and molecular weight distribution of the polymers which can explain the effects on the production process. The results illustrate that the range of product specifications may not always be tight enough to avoid variability in pharmaceutical processes like the preparation of hydrogel microspheres by an aqueous two-phase preparation process.     

Microsphere-based once-daily modified release matrix tablets for oral administration in angina pectoris

The objective of this research was to develop microsphere-based once-daily modified release tablet formulations of diltiazem hydrochloride (DH), a potent calcium channel blocker used in angina pectoris. For this purpose, DH-loaded microspheres were prepared by the solvent evaporation technique using Eudragit®RS 100. The effect of variation in the drug/polymer ratio on the physical and release characteristics of the microspheres was investigated. After the selection of the suitable microspheres, tablets were compressed using Compritol®888 ATO, Ludipress® and Cellactose®80 as different direct tableting agents and excipients. As a result, modified release tablet formulations of DH-loaded microspheres were designed successfully for oral administration once rather than two or three times a day in angina pectoris.     

Reversal of LPS induced endothelial cell TNF synthesis and increased permeability with microencapsulated antisense oligomers to NF-κB

Endothelial cells form the barrier between the circulation and interstitial space. Changes in permeability of endothelial cells allow penetration of inflammatory cells such as polymorphonuclear cells and macrophages to respond to infections and other inflammatory stimuli. Endothelial cells have also been shown to be phagocytic and produce pro-inflammatory cytokines such as TNF. It is the purpose of this study to evaluate endothelial cell phagocytosis of albumin microspheres containing antisense oligonucluetide to NF-κB (MASO), the effect of MASO on TNF synthesis after LPS stimulation and the effect of TNF inhibition on the permeability of endothelial cells in vitro. Results were (1) endothelial cells avidly phagocytozed albumin miocrospheres 1.0 and 1.7?µm in size, (2) phagocytosis of microspheres was potentiated by LPS, (3) TNF is synthesized by endothelial cells in cell culture with the peak concentrations occurring 4?h after stimulation with LPS, (4) MASO results in high intracellular concentration of oligomer, (5) MASO inhibits TNF synthesis to a greater extent than equivalent amounts of NF-κB antisense in solution and (6) the inhibition of TNF by MASO significantly decreases the permeability of albumin through endothelial cells in vitro.     

Mucoadhesive microspheres for nasal administration of cyclodextrins

The aim of this study was to examine the in vitro capacity of cyclodextrins to interfere on the β-amyloid fibril formation; then, mucoadhesive microspheres containing cyclodextrins were prepared and characterised as nasal delivery system for brain targeting. Eight batches of microspheres containing chitosan or alginate loaded with β-cyclodextrin or hydroxypropyl-β-cyclodextrin in two different cyclodextrin to polymer ratios were produced by spray drying. The results show that none of the tested CDs has direct cellular toxicity and they protect the cell viability from β-peptide. The microspheres prepared are characterised by small particle sizes, ability to absorb water and to delay the in vitro dissolution rate of the CDs; good ex vivo mucoadhesive properties of the formulations are assessed. The microsphere properties are influenced by the kind of polymer, of cyclodextrin and by cyclodextrin to polymer ratio used. In particular, the alginate formulation containing the higher cyclodextrin content shows the best performance.     

Prosthetic Rehabilitation of a Maxillectomy with a Two‐Piece Hollow Bulb Obturator. A Clinical Report

Extensive bilateral midfacial defects involving the upper jaw, palate, and sinus present a formidable reconstructive challenge. A combination of total and subtotal maxillectomy is, in general, a rare surgical procedure that affects the cosmetic, functional, and psychological aspects of a patient's life. Prosthetic restoration has become the preferred method for the rehabilitation of such conditions. The use of magnets is an efficient means of providing combined prostheses with retention, quality, and stability. This clinical report describes the rehabilitation of a total and subtotal maxillectomy patient with a two‐piece hollow bulb obturator retained with the help of magnets and a retention clasp.     

Poly(cyclotriphosphazene‐co‐tris(4‐hydroxyphenyl)ethane) Microspheres with Intrinsic Excitation Wavelength Tunable Multicolor Photoluminescence

Functional photoluminescent materials with a tunable multicolor emission without incorporation of metals is the current focus on luminescent materials due to their multifaceted applications. Herein, novel poly(cyclotriphosphazene‐co‐tris(4‐hydroxyphenyl)ethane) microspheres are synthesized with size distribution of ≈0.8–1.6 µm by reacting hexachlorocyclotriphosphazene and tris(4‐hydroxyphenyl)ethane at different molar ratios under facile conditions. The thermogravimetric analysis shows that the microspheres are highly thermally stable with 10% weight loss at around 500 °C. Fluorescence microscopy results show that the microspheres emit three blue, green, and red colors with an emission maximum at 487, 530, and 623 nm under different excitation wavelengths of 365, 420, and 546 nm, respectively. Furthermore, under UV and visible (365 and 420 nm) excitations, microspheres demonstrate extraordinary photobleaching stability and highly intense luminescence for expending time and repeating excitations. The microspheres also demonstrate semiconductor‐like optical absorption at 235–285 nm with a tail extended to 700 nm. This exploration provides an insight for the preparation of intrinsic superior wavelength tunable multicolor emission materials from phosphazene. These microspheres are potential candidates for anti‐counterfeits, solar cells, full spectrum fluorescence emitters, organic light emitting diodes, biological, catalysis applications and unlock new areas of research on multicolor photoluminescence.     

5Fu—聚乳酸微球的体外释药及其抗癌效应研究

研究生物可降解抗癌药５Ｆｕ－ＰＬＡ微球的释药特点，鉴定其体外杀伤肿瘤细胞的活性。方法采用恒温振荡透析法和一阶导数紫外分光光度法测定了５Ｆｕ－ＰＬＡ微球的药物释放特性；ＭＴＴ法测定了不同时相５Ｆｕ－ＰＬＡ微球对５种肿瘤细胞株的杀伤活性。结果：５Ｆｕ－ＰＬＡ微球具有良好的缓释功能，半量释放期ｔ１／２为１０．４天。５Ｆｕ－ＰＬＡ微球对５种肿瘤细胞株均有较强的杀伤活性，且杀伤活性与作用时间和释药量呈正相关     

Biomaterial-based scaffolds – current status and future directions

Introduction: Biomaterial-based scaffold formulations (three-dimensional Porous matrix, nano-fibre mesh, hydrogels and microspheres) are the major components that are used to deliver the bioactive molecules into the body organs through different routes for an effective treatment of various diseases.

Areas covered: Various fabrication techniques such as freeze-drying, polymerisation, spray drying, gas foaming, supercritical fluid technology, etc., are successfully used for fabrication of scaffold formulations. Due to their unique characteristics, these formulations are widely used against various diseases such as tuberculosis, bone defects, cartilage repair, skin diseases, cardiovascular diseases, periodontal diseases, wound dressing, etc.

Expert opinion: The study of biomaterial-based scaffold formulations is exhilarating with novel approaches to drug/cell/gene delivery being developed all the time. At present, there is a huge extent of research being performed worldwide on all aspects of tissue engineering/drug or gene delivery. In the future, the main focus will be on the development of more patient compliant, sustained and controlled delivery systems against various diseases by modification of polymers, manufacturing technologies as well as carrier systems.     

套筒冠固位加中空式赝复体修复老年人肿瘤术后单侧上颌骨缺损

目的:随访观察1-5年套筒冠固位加中空式赝复体修复老年人肿瘤术后的单侧上颌骨缺损的效果。方法:选择2005年1月至2010年1月门诊60岁以上老年人肿瘤术后的单侧上颌骨缺损伴牙槽骨缺失,口鼻相通伴发音差,健侧余留牙严重磨耗致咬合间隙小。采用套筒冠固位加中空式赝复体修复26例,随访观察1-5年复查修复体的密合性,美观与舒适,固位及稳定性,咬合关系和咀嚼功能,基牙牙周组织等。结果:随访观察1-5年套筒冠固位加中空式赝复体修复后效果:满意61.5%,基本满意34.6%,差3.8%,总满意率96.1%。结论:套筒冠固位加中空式赝复体修复老年人肿瘤术后的单侧上颌骨缺损效果较满意。