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The section of "Absorbent Incontinence Products," focuses on the different types of materials used as absorbents in diapers and other incontinence products. It is mentioned absorbents are primarily obtained from wood and common types of absorbents used are papers and fluff pulp. It is mentioned that most pulp is obtained from soft wood trees and different processes used for pulp production are discussed. It is stated that short fibres provides softness to diapers, whereas stiff fibres accounts for absorption capacity and high lignin imparts stiffness whereas resin decreases wettability. Information on other types of absorbents including hydrogels, melt-blown microfibres and foam and sponge is also presented.

Objectives: This paper describes the development and optimization of curcumin thermosensitive hydrogels (CTH), a kind of gel injection for intratumoral injection treatment. Methods: Aimed at increasing the content and stability of effective components, an optimal formulation of CTH was chosen based on the results from orthogonal tests and the optimal pH was determined by stability test. To investigate the hydrogels drug release in vitro, residence time by RP-HPLC and therapeutic effects on ascitic hepatocarcinoma cell strain with high metastasis potential in lymphatic system (HCA-F) solid tumors in mice. Key findings: The selected optimal formulation of CTH was: 0.2% curcumin, 20% poloxamer 407, 4% poloxamer 188, 8% polyethylene glycol 400, 12% 1,2-propanediol and pH was 6.0. The drug release determined by RP-HPLC fit to the Higuchi model. The residence time of CTH was longer than the curcumin suspensions. Intratumoral injection of the CTH can effectively inhibit the growth of HCA-F solid tumors in mice. Conclusions: The CTH prepared in this test demonstrates proper gel temperature and viscosity. It improves the solubility of curcumin with a relatively long period of drug release in vitro and residence time. Intratumoral injection of the CTH can effectively inhibit the growth of HCA-F solid tumors in mice. [ABSTRACT FROM AUTHOR]

In this paper, with W/O Pickering emulsion stabilized by modified SiO2 nanoparticles as template, PVA/SiO2 composite microspheres with PVA hydrogel cores and shells of SiO2 nanoparticles are successfully fabricated through freezing/thawing method. The final structure and constituents of the products are investigated through SEM, FT1R, and TGA. The PVA/SiO2 composite microspheres obtained are applied as a drug carrier to study their controlled release behaviors and methylene blue is used as a model drug. The effect of PVA concentration, SiO2 nanoparticle concentration, and freezing/ thawing cycles on the morphology of products and release behaviors is studied. All release curves are, respectively, fitted by Monoexponential equation, Higuchi equation, Weibull equation, and Hixson-Crowell equation. Weibull equation is found to give the best fit to the release process. The fitted results prove that the drug release from the PVA/SiO2 composite microspheres follows Fick diffusion. [ABSTRACT FROM AUTHOR]

Abstract: This paper highlights the use of hydrogels in controlled drug delivery, and their application in stimuli responsive, especially electro-responsive, drug release. electro-conductive hydrogels (ECHs) displaying electro-responsive drug release were synthesized from semi-interpenetrating networks (semi-IPNs) containing a poly(ethyleneimine) (PEI) and 1-vinylimidazole (VI) polymer blend as the novel electro-active species. The semi-IPNs are systems comprised of polyacrylic acid (PAA) and poly(vinyl alcohol) (PVA). This paper attempts to investigate the various attributes of the electro-responsive ECHs, through institution of a statistical experimental design. The construction of a Box–Behnken design model was employed for the systematic optimization of the ECH composition. The design model comprised of three variables, viz. poly(ethyleneimine) volume; 1-vinylimidazole volume; and applied voltage, critical to the success of the formulation. Electro-responsive drug release was determined on formulations exposed to varying environments to ascertain the optimal environment for the said desired release. A comparison method of formulation water content and swelling through gravimetric analysis was also conducted. Matrix resilience profiles were obtained as an insight to the ability of the ECH to revert to its original structure following applied stress. Response surface and contour plots were constructed for various response variables, namely electro-responsive drug release, matrix resilience and degree of swelling. The outcomes of the study demonstrated the success of electro-responsive drug release. The findings of the study can be utilized for the development of electro-responsive delivery systems of other drugs for the safer and effective drug delivery. Volumes of poly(ethyleneimine) (>2.6mL) and 1-vinylimidazole (>0.7mL), resulted in ideal therapeutic electro-responsive drug release (0.8mg) for indomethacin. Lower amounts of poly(ethyleneimine) and amounts of 1-vinylimidazole ranging from 0.2 to 0.74mL are consistent with greater than 1.6mg release per stimulation. Swelling of <25–45% was seen. [Copyright &y& Elsevier]

The present paper deals with the utilization of the cancer-lowering dietary fiber psyllium, for the development of double potential hydrogels meant for colon cancer drug delivery. The psyllium-acrylamide (AAm)-acrylic acid (AAc)-based hydrogels were synthesized by the radiation method and were characterized with FTIR, SEMs, and swelling behavior. Swelling and drug release mechanism were evaluated. The maximum water uptake (18.968 ± 0.880)g and (9.976 ± 0.364) g/g of gel were observed in solution of pH 7.4 buffer and solution of pH 2.2 buffer. respectively. The release of drug from the polymer matrix occurred through a Fickian-type diffusion mechanism. [ABSTRACT FROM AUTHOR]

The development of non-cytotoxic hydrogels that can allow for the controlled release of molecules has important clinical and therapeutic applications. In this paper, we developed a series of in situ hydrogels by combining N,O-carboxymethyl chitosan and oxidized alginate without additional crosslinking agents. The rheological properties of these hydrogels as well as their gelling time, swelling ratio, and in vitro degradation behavior were investigated. We observed that although gelation was rapid at physiological temperature, it was even faster in the presence of higher oxidization degree of alginate. In vitro cytotoxicity study showed that the developed hydrogels were not cytotoxic after 24 h of culturing with NIH-3T3 cells. Additionally, bovine serum albumin was released from the hydrogels initially by diffusion at early stages followed by a degradation-dependent mechanism at later stages. In conclusion, the developed hydrogel might have potential application in the drug delivery system and tissue engineering. [ABSTRACT FROM AUTHOR]

This paper describes a comparative study on the performances of ethosomes and solid lipid nanoparticle as delivery systems for acyclovir. Ethosomes were spontaneously produced by dissolution of phosphatidylcholine and acyclovir in ethanol followed by addition of an aqueous buffer while solid lipid nanoparticle were produced by homogenization and ultrasonification. Both colloidal systems were morphologically characterized by cryo-transmission electron microscopy. The encapsulation efficiency was 94.2±2.8% for ethosomes and 53.2±0.2% for solid lipid nanoparticle. Concerning Z potential, both formulations are close to neutrality. The diffusion coefficients of the drug from ethosomes and solid lipid nanoparticle, determined by a Franz cell method, were 9.4 and 1.2-fold lower as compared to the free acyclovir in solution, thus evidencing the ability of both colloidal systems in enhancing the diffusion of the drug. The antiviral activity against HSV-1 of both systems was tested by plaque reduction assay in monolayer cultures of Vero cells. Data showed that no significant differences in the antiviral activity were observed by acyclovir in the free or loaded forms. Taken together these results, colloidal systems could be interesting to mediate the penetration of acyclovir within Vero cells. [ABSTRACT FROM AUTHOR]

This paper explores the combination of cone beam optical computed tomography with an N-isopropylacrylamide (NIPAM)- based polymer gel dosimeter for three-dimensional dose imaging of small field deliveries. Initial investigations indicate that cone beam optical imaging of polymer gels is complicated by scattered stray light perturbation. This can lead to significant dosimetry failures in comparison to dose readout by magnetic resonance imaging (MRI). For example, only 60% of the voxels from an optical CT dose readout of a 1 l dosimeter passed a two-dimensional Low's gamma test (at a 3%, 3 mm criteria, relative to a treatment plan for a well-characterized pencil beam delivery). When the same dosimeter was probed by MRI, a 93% pass rate was observed. The optical dose measurement was improved after modifications to the dosimeter preparation, matching its performance with the imaging capabilities of the scanner. With the new dosimeter preparation, 99.7% of the optical CT voxels passed a Low's gamma test at the 3%, 3 mm criteria and 92.7% at a 2%, 2 mm criteria. The fitted interjar dose responses of a small sample set of modified dosimeters prepared (a) from the same gel batch and (b) from different gel batches prepared on the same day were found to be in agreement to within 3.6% and 3.8%, respectively, over the full dose range. Without drawing any statistical conclusions, this experiment gives a preliminary indication that intrabatch or interbatch NIPAM dosimeters prepared on the same day should be suitable for dose sensitivity calibration. [ABSTRACT FROM AUTHOR]

The design, development and evaluation of biomaterials that can sustain life or restore a certain body function, is a very important and rapidly expanding field in materials science. A key issue in the development of biomaterials is the design of a material that mimics the natural environment of cells. In the present work, we have therefore developed hydrogel materials that contain both a protein (gelatin) and a glycosaminoglycan (chondroitin sulphate) component. To enable a permanent crosslinking, gelatin and chondroitin sulphate were first chemically modified using methacrylic anhydride. Hydrogels containing modified gelatin (gel-MOD) and/or chondroitin sulphate (CS-MOD) were cryogenically treated as optimised earlier for gel-MOD based hydrogels (Van Vlierberghe et al., Biomacromolecules 8:331–337, 2007). The cryogenic treatment leads to tubular pores for gel-MOD based systems. For CS-MOD based hydrogels and hydrogels containing both gel-MOD and CS-MOD, a curtain-like architecture (i.e. parallel plates) was observed, depending on the applied CS-MOD concentration. In our opinion, this is the first paper in which such well-defined scaffold architectures have been obtained without using rapid prototyping techniques. [ABSTRACT FROM AUTHOR]

Abstract: Drug delivery systems based on polymeric nanocarriers have been widely exploited during the last years. However, one of the basic problems that is still not totally solved in this kind of systems is the ability of delivering drugs to specific target cells. Coating the nanocarrier with reactive antibodies against specific molecules presented in the external membrane of the target cells is a usual recommendation. In this paper, an ideal delivery system has been studied. Nanoparticles made of poly(d,l-lactic acid/glycolic acid) 50/50 (PLGA) polymers have been coated with polyclonal IgG. In the first part of the paper, some basic characteristics of these IgG–PLGA complexes have been analysed (i.e. size, electrophoretic mobility and colloidal stability). Then, the immunoreactivity of the immobilized IgG molecules was tested by using an optical device, monitoring the binding of a standard molecule (C-reactive protein, CRP) to the antibody (antiCRP–IgG) adsorbed on the PLGA particles. This allowed us to estimate the percentage of active IgG molecules on the PLGA particles by applying a simple kinetic model to the immunoreactivity results. According to this model, the PLGA–IgG particles supply a good immunoresponse even if only less than 5% of the total IgG molecules on the surface were active. Despite the simplicity of the system, the results may be of potential interest for developing more realistic nanocarriers with targeting ability. That is, it can be inferred that it is possible to obtain a high targeting specificity in IgG-sensitized nanocarriers even working with a low coverage of active antibody molecules. The results have been compared with those similarly obtained with polystyrene (PS) particles used as a reference system. [Copyright &y& Elsevier]

For many years there has been a debate about whether crystalloids or colloids should be used for resuscitation. Some years ago, albumin was the gold standard against which all other solutions were compared. This continues to be the case, despite the fact that other solutions are as effective for volume replacement. This paper stresses the need for a proper understanding of the properties of solutions that may influence the choice for volume replacement. Different classes of solutions are discussed in detail, with special reference to their effects on cardiovascular and oxygen transport parameters. Other important properties such as side-effects and effect on coagulation are also considered. [ABSTRACT FROM AUTHOR]

Background Usually serum albumin is measured with dye‐binding assay as bromocresol green (BCG) and bromocresol purple (BCP) methods. The aim of this paper was to examine the differences in albumin measurements between the Advia2400 BCG method (AlbBCG), Dimension RxL BCP (AlbBCP) and capillary zone electrophoresis (CZE). Methods Albumin concentrations from 165 serum samples were analysed using AlbBCG, AlbBCP and CZE. CZE was employed to estimate different serum protein fractions. Influence of globulins on albumin concentration discrepancies between methods was estimated as well as the impact of the albumin method on aCa concentrations. Medcalc was employed for statistical analysis, setting a value of P < 0.05 as significant. Results Correlation of AlbBCG and AlbBCP was r = 0.948 (p < 0.0001), but mean difference was large. Bland-Altman plots showed greater bias at lower albumin concentrations. AlbBCG were positively biased versus CZE (3.54 g/L). There was good agreement between CZE and ALbBCP (< 1 g/L). The AlbBCG assay bias shows a good correlation with alpha-1-globulin concentrations (r = 0.758); moderate and weak correlations were observed with CRP (r = 0.729) and alpha-2-globulin (r = 0.585); we found no correlation with beta-globulin (r = 0.120) or gamma-globulin (r = –0.303). Mean aCa based on AlbBCG and AlbBCP methods were 2.34 ± 0.15 mmol/L and 2.46 ± 0.16 mmol/L (p < 0.01), with a mean BCG-BCP difference of –0.12. Conclusion Albumin results from the BCP and BCG methods may result in unacceptable differences and clinical confusion, especially at lower albumin concentrations. Serum acute phase proteins contribute to overestimating the albumin concentration using AlbBCG. [ABSTRACT FROM AUTHOR]

The article discusses the efficacy of duct tape as a treatment for verruca vulgaris in children. The authors examine the evidence base for this treatment. They note that some patients reports mild skin irritation or erythema, discomfort and numbness. Bob Phillips, previous verruca sufferer, suggests to try to put the duct tape over the verruca for 6 weeks and try to use blaster gels if it causes redness or rubbing.

The mechanism of dracorhodin perchlorate for the repair of rat skin wounds was investigated. In order to screen a more favorable drug delivery system for wound repair, the therapeutic effect of dracorhodin perchlorate inflammation-targeted emulsion gel was compared with that of non-targeted emulsion gel on rat wounds. Compared with non-targeted emulsion gels, inflammation-targeted emulsion gels had a better transdermal penetration and lower potentials (−51.6 mV and −17.1 mV, respectively). The recovery of the wound from the dracorhodin perchlorate inflammation targeted emulsion gel group was better than that of the dracorhodin perchlorate inflammation non-targeted emulsion gel group and the positive drug group. Compared with the no-target emulsion gel group, the bFGF expression on day 7 and the EGF expression on day 14 in the targeted emulsion group showed 45.5% and 49.9% improvement, respectively. Pathological tissue slices showed that the epidermis, dermis, and basal layer inflammatory cells in the inflammation-targeted emulsion gel group and non-targeted emulsion gel group were significantly reduced, the granulation tissue proliferation was obvious, and the inflammation-targeted emulsion gel group was more effective. The results proved that dracorhodin perchlorate had a repairing effect on rat skin wounds, and its mechanism might be related to the promotion of the expression of EGF and bFGF in tissues. [ABSTRACT FROM AUTHOR]

Biopolymeric hydrogels that mimic the properties of extracellular matrix have great potential in promoting cellular migration and proliferation for tissue regeneration. The authors reported earlier that rapidly gelling, biodegradable, injectable hydrogels can be prepared by self-crosslinking of periodate oxidized alginate and gelatin in the presence of borax, without using any toxic crosslinking agents. The present paper investigates the suitability of this hydrogel as a minimally invasive injectable, cell-attractive and adhesive scaffold for cartilage tissue engineering for the treatment of osteoarthritis. Time and frequency sweep rheology analysis confirmed gel formation within 20s. The hydrogel integrated well with the cartilage tissue, with a burst pressure of 70±3mmHg, indicating its adhesive nature. Hydrogel induced negligible inflammatory and oxidative stress responses, a prerequisite for the management and treatment of osteoarthritis. Scanning electron microscopy images of primary murine chondrocytes encapsulated within the matrix revealed attachment of cells onto the hydrogel matrix. Chondrocytes demonstrated viability, proliferation and migration within the matrix, while maintaining their phenotype, as seen by expression of collagen type II and aggrecan, and functionality, as seen by enhanced glycosoaminoglycan (GAG) deposition with time. DNA content and GAG deposition of chondrocytes within the matrix can be tuned by incorporation of bioactive signaling molecules such as dexamethasone, chondroitin sulphate, platelet derived growth factor (PDGF-BB) and combination of these three agents. The results suggest that self-crosslinked oxidized alginate/gelatin hydrogel may be a promising injectable, cell-attracting adhesive matrix for neo-cartilage formation in the management and treatment of osteoarthritis. [ABSTRACT FROM AUTHOR]

Abstract: Maintaining the mechanical properties of biofunctional hydrogels of natural resources for tissue engineering and biomedical applications for an intended period of duration is a challenge. Though anionic polysaccharide alginate has been hailed for its excellent biomimetic characters for tissue engineering, it usually fails in load bearing and other dynamic mechanical environment. In this paper this issue was addressed by copolymerizing alginate with the biocompatible and mechanically robust synthetic biodegradable polyester and crosslinking with polyethylene glycol diacrylate (PEGDA) and vinyl co-monomers, 2-hydroxy ethyl methacrylate (HEMA), methyl methacrylate (MMA) and N N׳ methylene bis acrylamide (NMBA) to form three hydrogels. All three hydrogels were amphiphilic, hemocompatible and non-cytotoxic. These hydrogels exhibited appreciable water holding capacity. Comparatively, hydrogel prepared with PEGDA–NMBA crosslinkers displayed larger pore size, increased crosslinking, higher tensile strength and controlled degradation. With appreciable swelling and EWC, this hydrogel elicited better biological responses with long-term cell viability for cardiac tissue engineering. [Copyright &y& Elsevier]

Abstract: In the paper, we begin by describing polyethylene glycol–poly lactic acid-co-glycolic acid (PEG–PLGA) which was chosen as a typical model copolymer for the construction of nano-sized drug delivery systems and also the types of PEG–PLGA copolymers that were eluted. Following this we examine the structure-influenced drug delivery applications including nanoparticles, micelles and hydrogels. After that, the preparation methods for nano-sized delivery systems are presented. In addition, the drug loading mode of PEG–PLGA micelles is divided into three aspects. Finally, the drug release profiles of PEG–PLGA micelles, both in terms of their in vitro and in vivo characteristics, are represented. PEG–PLGA copolymers are very suitable for the construction of micelles as carriers for insoluble drugs. This article reviews the structure and the different structure-influenced applications of PEG–PLGA copolymers, concentrating on the application of PEG–PLGA micelles. [Copyright &y& Elsevier]

Abstract: The increasing realisation of the impact of size and surface properties on the bio-distribution of drug loaded colloidal particles has driven the application of micro fabrication technologies for the precise engineering of drug loaded microparticles. This paper demonstrates an alternative approach for producing size controlled drug loaded PLGA based microparticles using silicon Microfluidic Flow Focusing Devices (MFFDs). Based on the precise geometry and dimensions of the flow focusing channel, microparticle size was successfully optimised by modifying the polymer type, disperse phase (Q d) flow rate, and continuous phase (Q c) flow rate. The microparticles produced ranged in sizes from 5 to 50μm and were highly monodisperse (coefficient of variation <5%). A comparison of Ciclosporin (CsA) loaded PLGA microparticles produced by MFFDs vs conventional production techniques was also performed. MFFDs produced microparticles with a narrower size distribution profile, relative to the conventional approaches. In-vitro release kinetics of CsA was found to be influenced by the production technique, with the MFFD approach demonstrating the slowest rate of release over 7 days (4.99±0.26%). Finally, MFFDs were utilised to produce pegylated microparticles using the block co-polymer, PEG-PLGA. In contrast to the smooth microparticles produced using PLGA, PEG-PLGA microparticles displayed a highly porous surface morphology and rapid CsA release, with 85±6.68% CsA released after 24h. The findings from this study demonstrate the utility of silicon MFFDs for the precise control of size and surface morphology of PLGA based microparticles with potential drug delivery applications. [Copyright &y& Elsevier]

Abstract: In this paper, a lipid material glycerol monooleate was used as the starting material to synthesize the oxidized glycerol monooleate (OGMO). OGMO was subsequently linked to chitosan (CS) via imine bonds ( C N ) to obtain a new chitosan-based polymer (OGMO-CS), which can form hydrogels rapidly in aqueous media. Scanning electron microscopy, swelling behavior studies and degradation kinetics studies were performed to demonstrate the effect of this synthetic modification on the hydrogels formation of chitosan network and in vitro drug release. The effects of OGMO-CS type, dry hydrogels percentage, release media and drug loading on the sustained release of the model drug trimetazidine hydrochloride were evaluated. The release profiles of the hydrogels could be described by the Peppas–Sahlin mechanism, a combination of Fickian diffusion and Case-II relaxation. Based on the fact that numerous pharmaceutical lipids are available, the present study may pave the way for other lipids to be employed as modifiers of chitosan for more innovative chitosan derivatives with versatile properties and pharmaceutical applications. [Copyright &y& Elsevier]

While soft hydrogel nano- and microstructureshold great potentialfor therapeutic treatments and in vivo applications, their nanomechanicalcharacterization remains a challenge. In this paper, soft, single-component,supported hydrogel films were fabricated using pendant-thiol-modifiedpoly(methacrylic acid) (PMASH). The influence of hydrogelarchitecture on deformation properties was studied by fabricatingfilms on particle supports and producing free-standing capsules. Theinfluence of the degree of thiol-based cross-linking on the mechanicalproperties of the soft hydrogel systems (core–shell and capsules)was studied using a colloidal-probe (CP) AFM technique. It was foundthat film mechanical properties, stability, and capsule swelling couldbe finely tuned by controlling the extent of poly(methacrylic acid)thiol modification. Furthermore, switching the pH from 7.4 to 4.0led to film densification due to increased hydrogen bonding. Hydrogelcapsule systems were found to have stiffness values ranging from 0.9to 16.9 mN m-1over a thiol modification range of5 to 20 mol %. These values are significantly greater than those forpreviously reported PMASHplanar films of 0.7–5.7mN m–1over the same thiol modification range (Best et al., Soft Matter2013, 9, 4580–4584). Films on particlesubstrates had comparable mechanical properties to planar films, demonstratingthat while substrate geometry has a negligible effect, membrane andtension effects may play an important role in capsule force resistance.Further, when transitioning from solid-supported films to free-standingcapsules, simple predictions of shell stiffness based on modulus changesfound for supported films are not valid. Rather, additional effectslike diameter increases (geometrical changes) as well as tension buildupneed to be taken into account. These results are important for researchrelated to the characterization of soft hydrogel materials and controlover their mechanical properties. [ABSTRACT FROM AUTHOR]

Abstract: Wound dressings of chitosan are biocompatible, biodegradable, antibacterial and hemostatic biomaterials. However, applications for chitosan are limited due to its poor mechanical properties. Here, we conducted an in vivo mouse angiogenesis study on reinforced poly(ethylene glycol) (PEG)-chitosan (RPC) hydrogels. RPC hydrogels were formed by cross-linking chitosan with PEGs of different molecular weights at various PEG to chitosan ratios in our previous paper. These dressings can keep the wound moist, had good gas exchange capacity, and was capable of absorbing or removing the wound exudate. We examined the ability of these RPC hydrogels and neat chitosan to heal small cuts and full-thickness skin defects on the backs of male Balb/c mice. Histological examination revealed that chitosan suppressed the infiltration of inflammatory cells and accelerated fibroblast proliferation, while PEG enhanced epithelial migration. The RPC hydrogels promoted wound healing in the small cuts and full layer wounds. The optimal RPC hydrogel had a swelling ratio of 100% and a water vapor transmission rate (WVTR) of about 2000g/m2/day. In addition, they possess good mechanical property and appropriate degradation rates. Thus, the optimal RPC hydrogel formulation functioned effectively as a wound dressing and promoted wound healing. [Copyright &y& Elsevier]

Abstract: Peripheral nerve injury still remains a refractory challenge for both clinical and basic researchers. A novel nanofiber conduit made of blood vessel and filled with amphiphilic hydrogel of self-assembling nanofiber scaffold (SAPNS) was implanted to repair a 10 mm nerve gap after sciatic nerve transection. Empty blood vessel conduit was implanted serving as control. Results showed that this novel nanofiber conduit enabled the peripheral axons to regenerate across and beyond the 10 mm gap. Motoneuron protection, axonal regeneration and remyelination were significantly enhanced with SAPNS scaffold treatments. The target reinnervation and functional recovery induced by the regenerative nerve conduit suggest that SAPNS-based conduit is highly promising application in the treatment of peripheral nerve defect. From the Clinical Editor: In this paper by Zhan et al, a novel self-assembling nanofiber scaffold is reported to promote regeneration of peripheral nerves in a sciatic nerve injury model. The promising results and the obvious medical need raises hope for a clinical translation of this approach hopefully in the near future. [Copyright &y& Elsevier]

Nowadays solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) have been investigated as carrier systems for many applications. SLNs consist of pure solid lipids, while NLCs are made of a solid matrix that entraps liquid lipid nano-compartments. These systems revealed several advantages compared to other colloidal carrier systems. They provide a controlled drug release and an increase in chemical stability of the incorporated drugs. Moreover, they are safe carriers which can be produced easily in a large scale. This paper reviews the commonly used materials, production techniques, characterization, and physical stability of these systems. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes a methodology to produce hydrogel films, composed of alginate and Aloe vera, for wound healing and drug delivery applications. The films were prepared through the solvent-casting method and subsequently submitted to an additional cross-linking step to improve their properties. Alginate films with different Aloe vera contents (5, 15 and 25%) were prepared and its properties evaluated in terms of thickness, transparency, swelling behavior and in vitro degradation. Results show a positive influence of Aloe vera on the transparency of the films, in both dry and wet state. Films were immersed in acetate buffer at pH 5.5 simulating the value of the skin, to evaluate its water absorption capacity. It was found that water absorption increases as the Aloe vera content increases, suggesting that Aloe vera enhances the hydrophilic properties of the films. The in vitro degradation tests were performed through the incubation of the films, for 10 weeks, in a simulated body fluid at 37°C. After this period, films kept its structure integrity exhibiting a weight loss in the range of 14.1-18.6%. [Copyright &y& Elsevier]

Abstract: Recently, colloidal carrier systems have been receiving much attention in the field of drug targeting because of their high loading capacity for drugs as well as their unique disposition characteristics in the body. This paper highlights the utility of polymeric micelles formed through the multimolecular assembly of block copolymers as novel core–shell typed colloidal carriers for drug and gene targeting. The process of micellization in aqueous milieu is described in detail based on differences in the driving force of core segregation, including hydrophobic interaction, electrostatic interaction, metal complexation, and hydrogen bonding of constituent block copolymers. The segregated core embedded in the hydrophilic palisade is shown to function as a reservoir for genes, enzymes, and a variety of drugs with diverse characteristics. Functionalization of the outer surface of the polymeric micelle to modify its physicochemical and biological properties is reviewed from the standpoint of designing micellar carrier systems for receptor-mediated drug delivery. Further, the distribution of polymeric micelles is described to demonstrate their long-circulating characteristics and significant tumor accumulation, emphasizing their promising utility in tumor-targeting therapy. As an important perspective on carrier systems based on polymeric micelles, their feasibility as non-viral gene vectors is also summarized in this review article. [Copyright &y& Elsevier]

Abstract: In our previous work, a new kind of pH-sensitive hydrogel based on poly (lactic acid) (PLA), methoxyl poly (ethylene glycol) (MPEG) and itaconic acid (IA) was prepared by heat-initiated free radical polymerization without any organic solvent. For further application, the safety of prepared copolymers and hydrogels was evaluated in vitro and in vivo in this paper. In vitro toxicity evaluation of MPEG–PLA–AC (PLE–AC) copolymers included hemolytic test and cytotoxicity which were evaluated by cell viability assay using HEK293 cells. In vivo acute toxicity tests and histopathological study of PLE–AC copolymers were carried out on BALB/c mice which were administrated copolymers (1g/kgb.w.) intravenously. In acute toxicity test, the mice were observed continuously for 7 days, their body weight obtained everyday, at last the mice were sacrificed for the following study: the blood of the mice was assigned for blood chemistry and routine analysis, the heart, liver, spleen, lung, and kidneys were used for histopathological study. In acute oral toxicity test, mice were orally administered with a total 15g/kgbody weight (b.w.) of P(LE-IA-MEG) hydrogels, and were observed continuously for 14 days. For histopathologic study, samples including heart, liver, lung, kidneys, spleen, stomach, and intestine, were histochemically prepared and stained with hematoxylin–eosin for histopathologic examination. All results indicated that the PLE–AC copolymers and pH-sensitive hydrogels were non-toxic. Therefore it might be used as a safe candidate for drug delivery system. [Copyright &y& Elsevier]

Abstract: Chitosan, a natural cationic polysaccharide, is prepared industrially by the hydrolysis of the aminoacetyl groups of chitin, a naturally available marine polymer. Chitosan is a non-toxic, biocompatible and biodegradable polymer and has attracted considerable interest in a wide range of biomedical and pharmaceutical applications including drug delivery, cosmetics, and tissue engineering. The primary hydroxyl and amine groups located on the backbone of chitosan are responsible for the reactivity of the polymer and also act as sites for chemical modification. However, chitosan has certain limitations for use in controlled drug delivery and tissue engineering. These limitations can be overcome by chemical modification. Thus, modified chitosan hydrogels have gained importance in current research on drug delivery and tissue engineering systems. This paper reviews the general properties of chitosan, various methods of modification, and applications of modified chitosan hydrogels. [Copyright &y& Elsevier]

Abstract: Temporomandibular joint (TMJ) ankylosis is a devastating anatomico-pathological condition which severely affects the quality of human health. Over the last 70years various treatments have been described to treat this distressing condition. But no single method has uniformly produced successful results. Although various surgical techniques have been improved periodically, the treatment results remain inefficient due to its recurrence as TMJ re-adhesion. Since recurrence remains as a problem in many cases, the TMJ ankylosis presents a major therapeutic challenge in head and neck surgery. The re-ankylosis is a unique phenomenon that so far has defied a full and logical explanation, based upon biological and mechanical factors that are linked together in a coherent fashion. Many factors have been implicated in the development of re-adhesion following TMJ surgery. But still the mechanism by which the TMJ re-adhesion develops is unclear. Hence, TMJ ankylosis demands an alternative effective treatment modality to prevent its recurrence as re-ankylosis. This paper postulates some critical biological factors responsible for re-ankylosis based on which a novel treatment modality is also proposed. [Copyright &y& Elsevier]

Abstract: The paper describes sterically stabilized lipid nanocapsules (LNC) and multilamellar liposomes (MLV) coated using a new amphiphilic conjugate of PEG2000 with a 2-alkyl-lipoamino acid (LAA). A complement activation assay (CH50) and uptake experiments by THP-1 macrophage cells were used to assess in vitro the effectiveness of the PEG-LAA derivative of modifying the surface behavior of nanocarriers. Administered to rats or Swiss mice, respectively, the PEG2000-LAA—modified LNC and MLV showed plasma half-lives longer than the corresponding naked carriers. To assess the ability of nanocarriers to specifically reach tumor sites, paclitaxel (PTX)—loaded LNC and MLV were administered subcutaneously to rats implanted with a 9L glioma. Animals treated with saline or naked LNC and MLV underwent a quick expansion of tumor mass, up to a volume of 2000mm3 25 days after the injection of tumor cells. On the contrary, treatment with a PEG-LAA modified LNC carrier reduced the growth of the tumor volume, which did not exceed 1000mm3 by day 25. Analogous positive results were obtained with the liposomal systems. The experimental findings confirmed that these new PEG-LAA conjugates allow to obtain sterically stable nanocarriers that behave effectively and in a comparable or even better way than the (phospho)lipid PEG derivatives commercially available. [Copyright &y& Elsevier]

A novel pH-sensitive composite hydrogel (CH) namely 2-Acrylamido-2-methylpropane sulfonic acid (AMPS) grafted N-maleoylchitosan (MACTS) intercalated montmorillonite has been synthesized by in situintercalation graft copolymerization of AMPS with MACTS intercalated MMT (MACTS/MMT) by using potassium persulfate (KPS) as a free radical initiator, in the presence of N,N-methylenebisacrylamide (MBA) as a crosslinking agent. A hydrophilic anticancer drug, 5-fluorouracil (5-FLU), has been chosen to investigate the loading and release properties of the CH. The CH formation and 5-FLU loading ability of CH have been confirmed by FTIR. X-Ray diffraction (XRD) analysis supports the intercalation reaction of MACTS with MMT, since after intercalation reaction there is an increase in basal spacing. A scanning electron microscopy (SEM) image of drug loaded CH shows a smoother surface whereas blank CH has a cracked and rough surface, this reveals the high affinity of 5-FLU to CH. The encapsulation efficiency of CH reaches the maximum value of 94.0% with CH prepared using 4.0 g of MACTS/MMT, 1.5 g of AMPS, 0.75 g of MBA and 75.0% of drug loading. Swelling profiles obtained show that the CH swelling rate increases with increase of pH up to 6.4 and then starts to decrease. Release profiles of 5-FLU from CH have been studied under both simulated gastric and intestinal pH conditions. The results obtained show that the release rate of the loaded drug molecules was slow at pH 2.4 but increased significantly at pH 7.4. The cell viability test displayed that the 5-FLU loaded CH exhibited an enhanced cell inhibition than that of pure 5-FLU. The studies described in the paper demonstrate the potential viability of a pH-sensitive CH carrier for colon specific anticancer drugs. [ABSTRACT FROM AUTHOR]

Abstract: Combinations of microcrystalline cellulose (MCC) and sodium carboxymethyl cellulose (Na-CMC) are commonly used as stabilising agents and suspending agents in pharmaceutical formulations. This paper is based on a study of the interactions that take place during the process of hydrogel formation, break down, and recovery. Also considered is the binding that occurs between the MCC and the Na-CMC. Avicel RC 591, a processed mixture of MCC and Na-CMC, is one of the more commonly used commercial suspending agents for aqueous compositions. Avicel RC 591 is used as an effective, blended stabilising agent. In this study, the contributions made by each of the components of Avicel RC 591 have been rationalised by monitoring the behaviour of the individual components in Avicel RC 591 suspensions or solutions. The hydrogels that are formed by Avicel RC 591 and by their laboratory formulated equivalent, which is spray dried (MCC+Na-CMC), have been characterised by confocal microscopy scanning electron microscopy and by dynamic light scattering. A 3D network structure that is formed by the MCC, in Avicel RC 591 is visualised. This network is supported by hydrogen bonding and by ionic interactions among and between the MCC, the Na-CMC and water. The strength of the network determines the physical properties of the hydrogel system, as seen in the rheological behaviour. [Copyright &y& Elsevier]

From the viewpoint of colloidal transport phenomena, the individual drug particle's movement through the tumor is studied by using the square network model. The effects of drug concentration, arterial pressure, and interstitial pressure of the tumor on the concentration breakthrough moment of drug particles are investigated by using the Brownian dynamics simulation method. From the simulation results, we find that the present network model and the Brownian dynamics simulation method can successfully analysis the therapeutic ranges achieved by the drug particles in the tumor at different magnitudes of the drug concentration, the inlet blood velocity, the arterial pressures, and the interstitial pressures of the tumor. Because of the high interstitial fluid pressure, the drug particles can only reach the peripheral region and cannot penetrate inside the target tumor efficiently, and the decreased interstitial fluid pressure will lead more drug particles to penetrate inside the tumor. [ABSTRACT FROM AUTHOR]

Abstract: To effectively repair or replace damaged tissues, it is necessary to design scaffolds with tunable structural and biomechanical properties that closely mimic the host tissue. In this paper, we describe a newly synthesized photocrosslinkable interpenetrating polymer network (IPN) hydrogel based on gelatin methacrylate (GelMA) and silk fibroin (SF) formed by sequential polymerization, which possesses tunable structural and biological properties. Experimental results revealed that IPNs, where both the GelMA and SF were independently crosslinked in interpenetrating networks, demonstrated a lower swelling ratio, higher compressive modulus and lower degradation rate as compared to the GelMA and semi-IPN hydrogels, where only GelMA was crosslinked. These differences were likely caused by a higher degree of overall crosslinking due to the presence of crystallized SF in the IPN hydrogels. NIH-3T3 fibroblasts readily attached to, spread and proliferated on the surface of IPN hydrogels, as demonstrated by F-actin staining and analysis of mitochondrial activity (MTT). In addition, photolithography combined with lyophilization techniques was used to fabricate three-dimensional micropatterned and porous microscaffolds from GelMA–SF IPN hydrogels, furthering their versatility for use in various microscale tissue engineering applications. Overall, this study introduces a class of photocrosslinkable, mechanically robust and tunable IPN hydrogels that could be useful for various tissue engineering and regenerative medicine applications. [Copyright &y& Elsevier]

Abstract: Biomaterials that actively promote both wound healing and angiogenesis are of critical importance for many biomedical applications, including tissue engineering. In particular, hyaluronic acid (HA) is an important player that has multiple roles throughout the angiogenic process in the body. Previously, our laboratory has developed photocrosslinkable HA-based scaffolds that promote angiogenesis when implanted in vivo. This paper reports the incorporation of a photocrosslinkable fibronectin (FN) conjugate into three-dimensional (3-D) HA hydrogel networks to enhance endothelial cell adhesion and angiogenesis. The results demonstrate significantly better retention of FN that was photocrosslinked within HA hydrogels compared to FN that was physically adsorbed within HA hydrogels. Increased viability of endothelial cells cultured in 3-D HA hydrogels with photoimmobilized FN, compared to adsorbed FN, was also observed. Endothelial cells were cultured within hydrogels for up to 6days, a period over which cell proliferation, migration and an angiogenic phenotype were influenced by varying the concentration of incorporated FN. The results demonstrate the potential of these composite hydrogels as biomaterial scaffolds capable of promoting wound healing and angiogenesis. [Copyright &y& Elsevier]

Background: Fluid resuscitation after severe burns remains a challenging task particularly in the preclinical and early clinical phases. To facilitate volume substitution after burn trauma several formulae have been published and evaluated, nevertheless, the optimal formula has not yet been identified. Methods: A systematic PubMed search was performed to identify published formulae for fluid resuscitation after severe burns. The search terms 'burn', 'thermal', 'treatment', 'therapy' or 'resuscitation', 'fluid', 'formula' and 'adult', 'pediatric' or 'paediatric' were used in various combinations. Analysis was limited to the period from 01.01.1950 to 30.06.2010 and database entries in PubMed (http://www.pubmed.com). Additionally, references cited in the papers were analyzed and relevant publications were also included. Publications and formulae were assessed and classified by two independent investigators. Results: Within the specified time frame eight publications (five original contributions and three book chapters) were identified of which three formulae recommended colloid solutions, four recommended electrolyte solutions and one suggested hypertonic solutions within the first 24 h for fluid resuscitation. Only one formula specifically dealt with fluid resuscitation in infants. Conclusion: The identified formulae led to sometimes strikingly diverse calculations of resuscitation fluid volumes. Therefore their use should be monitored closely and clinical values included. Urine output is a well established individual parameter. Use of colloid and hypertonic solutions leads to a reduced total fluid volume but is still controversially discussed. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the results of an experimental study of the effects of temperature on the diffusion from poly(N-isopropylacrylamide) (PNIPA)-based gels with hydrophilic (acrylamide) or hydrophobic (butyl methacrylate) co-monomers. The elutions of rhodamine dye and cancer drug, paclitaxel™ are studied over a range of temperatures in which localized chemotherapy can be combined with hyperthermia (37–45°C). Dye and drug release from the gels is shown to be well described by monolithic and membrane diffusion models. The current work introduces a multi-modal device that can potentially kill cancer cells by chemotherapy and hyperthermia. A clear advantage over prior devices is the ability to combine these two therapeutic interventions in one device. The implications of the results are discussed for the development of thermosensitive drug eluting Bio-Micro-Electro-Mechanical Systems (BioMEMS) devices that can treat cancer locally via the combined effects of chemotherapy and hyperthermia. [ABSTRACT FROM AUTHOR]

In this paper, we report the synthesis and characterization of a novel cross-linked N-isopropylacrylamide-acrylic acid-hydroxyethyl methacrylate [P (NIPASM-AA-HEM)] hydrogel nanoparticles (NPs) containing amoxicillin. The aim of present study was to investigate whether these hydrogel NPs have the potential to be used in antibiotic delivery to stomach for treatment of Helicobacter pylori. Amoxicillin-loaded hydrogel NPs were prepared using cross-linked P (NIPASM-AA-HEM) as mucoadhesive polymer for the potential use of treating gastric and duodenal ulcers. Aiming at predicting the in vivo behavior of the amoxicillin-loaded NPs, the physicochemical properties in terms of entrapment efficiency (EE%), mean diameter, and morphology of NPs was evaluated. The dependence of the EE% of the drug on the organic to aqueous phase ratio was also studied. The profile of amoxicillin release from P (NIPASM-AA-HEM) NPs system was studied under various conditions. In all these experiments, amoxicillin release in the free form was studied by ultraviolet (UV) spectrophotometric analysis. Experimental results showed that at pH 7.4, drug release rises when polymer concentration in the formulation increases; in human plasma on the contrary, drug release is reduced as concentration of the polymer in the formulation rises. In vitro amoxicillin release rate was also higher in pH 1 than that in pH 7.4. About 88.5% of amoxicillin entrapped in the NPs was released in 4 h in the pH 1.0 medium, whereas in phosphate buffer at pH 7.4 no more than 45% was released after 4 h incubation at 37°C. Amoxicillin concentration in rat's gastric tissue was determined. The results of in vivo studies showed that the hydrogel NPs enhance drug concentration at topical site than powder amoxicillin. Thus, amoxicillin-loaded hydrogel NPs may provide therapeutic concentration at a much lower dose that may reduce the adverse effects of amoxicillin in high doses. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 100:1057-1066, 2011 [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we describe a simple method for fabricating micropatterned nanoporous substrates that are capable of controlling the spatial positioning of mammalian cells. Micropatterned substrates were prepared by fabricating poly(ethylene glycol) (PEG) hydrogel microstructures on alumina membranes with 200nm nanopores using photolithography. Because hydrogel precursor solution could infiltrate and become crosslinked within the nanopores, the resultant hydrogel micropatterns were firmly anchored on the substrate without the use of adhesion-promoting monolayers, thereby allow tailoring of the surface properties of unpatterned nanoporous areas. For mammalian cell patterning, arrays of microwells of different dimensions were fabricated. These microwells were composed of hydrophilic PEG hydrogel walls surrounding nanoporous bottoms that were modified with cell-adhesive Arg–Gly–Asp (RGD) peptides. Because the PEG hydrogel was non-adhesive towards proteins and cells, cells adhered selectively and remained viable within the RGD-modified nanoporous regions, thereby creating cellular micropatterns. Although the morphology of cell clusters and the number of cells inside one microwell were dependent on the lateral dimension of the microwells, adhered cells that were in direct contact with nanopores were able to penetrate into the nanopores by small extensions (filopodia) for all the different sizes of microwells evaluated. [Copyright &y& Elsevier]

Abstract: A thermoreversible nanoparticle hydrogels based on carboxylated methoxy poly(ethylene glycol)-grafted chitosan (N-CS-g-mPEG) were investigated in this paper. The aqueous dispersion of N-CS-g-mPEG nanoparticle freeze-dried powder (NP-FDP) can undergo reversible gel–sol transition as the temperature changes. The structures of N-CS-g-mPEG NPs and hydrogels were characterized by TEM, DLS and ESEM. Using 5-Fluorouracil (5-FU), bovine serum albumin (BSA) and dexamethasone (DXM) as model drugs, in vitro release behaviors of drug-loaded hydrogels were also investigated. The release results show that there is a sustained release of BSA and DXM from the drug-loaded hydrogel. In vitro cytotoxicity tests investigated by MTT assay indicate that N-CS-g-mPEG is non-toxic to normal mouse embryonic fibroblast cells (3T3). Therefore, the thermoreversible N-CS-g-mPEG NP hydrogels could be potentially applied in a local minimally invasive drug delivery system. [Copyright &y& Elsevier]

In attempt to overcome the problem of low water solubility and severe toxicity of camptothecin (CPT) after intravenous administration, a novel drug carrier system based on chitosan (CS) and dibasic sodium phosphate (DSP) has been developed in this paper to encapsulate CPT intending for local administration. Nanocolloids of CPT with size about 500 nm were first prepared, followed by encapsulation in the chitosan/dibasic sodium phosphate (CS/DSP) formulation. The formulation was sol state below 37°C and transformed to nonflowing gel state at 37°C. Encapsulation of CPT nanocolloids had greatly effect on the gelling time as well as the micro-structure of hydrogel. In vitro and in vivo degradation studies revealed that the developed CS/DSP hydrogel was biodegradable and biocompatible. In vitro release study revealed that CPT released from CS/DSP hydrogel in an extended period with about 70% of total CPT released from hydrogel after 18 days. Furthermore, nearly 90% of CPT in the chitosan hydrogels could be preserved in the lactone form (active form) even after 7 days's storage at 37°C. Furthermore, in vitro cytotoxicity of CPT nanocolloids on SKOV3 human ovarian cancer cells suggested the well anti-tumor cell efficiency could be gained at a lower concentration. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 100:232-241, 2011 [ABSTRACT FROM AUTHOR]

Abstract: Synthetic hydrogels are important biomaterials for many biomedical applications and hydrogels produced via photo-gelation have shown particular promise. In this paper, we describe a new family of biodegradable hybrid hydrogels fabricated in aqueous solution via long wavelength UV photo-crosslinking using maleic chitosan and polyethylene glycol diacrylate (PEGDA) as precursors. The maleic chitosan precursor was prepared by a simple one-step chemical modification of chitosan, with high yields, and characterized by Fourier transform infrared spectroscopy, 1H NMR and 13C NMR. Maleic chitosan and PEGDA precursors at a wide range of weight feed ratios were mixed in aqueous solution and directly photo-crosslinked for 10min under a long wavelength UV light (365nm) using 4-(2-hydroxyethoxy) phenyl-(2-hydroxy-2-propyl) ketone (Irgacure 2959) as photoinitiator. It was observed that as the weight feed ratio of maleic chitosan to PEGDA decreased the pore sizes of the hydrogel samples decreased, thereby increasing the densities of the hydrogel networks and producing a lower swelling ratio and a higher compressive modulus. The molecular weight of PEGDA had a similar effect. Preliminary cell cytotoxicity tests of both the maleic chitosan precursor and maleic chitosan/PEGDA hydrogels, based on the MTT assay and live–dead assay, respectively, showed that these new chitosan-based biodegradable biomaterials were relatively non-toxic to bovine aortic endothelial cells at low dosages. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a novel class of microspheric hydrogels was synthesized by grafting of N-isopropyacrylamide (NIPAAm) with gelatin. The possibility of inserting commercial gelatin in a crosslinked structure bearing thermo-sensitive moieties, by radical process, represents an interesting innovation that significantly improves the device performance, opening new applications in biomedical and pharmaceutical fields. This synthetic approach allows a modification of the polymeric network composition, producing hydrogels with suitable physico-chemical properties and a transition temperature higher than NIPAAm homopolymers. The incorporation of monomers into the network was confirmed by infrared spectroscopy, and the composition of the polymerization feed was found to strictly influence the network density and the shape of hydrogels. Thermal analyses showed negative thermo-responsive behaviour with shrinking/swelling transition values in the temperature range 34.6–34.8°C, according to the amount of the hydrophilic portions in the network. In order to test the preformed materials as drug carriers, diclofenac sodium salt was loaded into the spherical microparticles. After the determination of the drug entrapment percent, drug release profiles in media at different temperature were analysed. By using semi-empirical equations, the release mechanism was extensively studied and the diffusional contribution was evaluated. [ABSTRACT FROM AUTHOR]

Abstract: Hydrogels are synthetic or natural polymer networks that closely mimic native extracellular matrices. As hydrogel-based vehicles are being increasingly employed in therapeutic cell delivery, two inherent traits of most common hydrogels, namely low cell affinity and high cell constraint, have significantly drawn the attention of biomedical community. These two properties lead to the unfavourable settlement of anchorage-dependent cells (ADCs) and unsatisfactory cell delivery or tissue formation in hydrogel matrices. Tissue engineers have correspondingly made many efforts involving chemical modification or physical hybridisation to facilitate ADC settlement and promote tissue formation. On the other hand, these two ‘bio-inert’ characteristics have particularly favoured oncological cell therapists, who expect to utilize hydrogels to provide sufficiently high confinement of the delivered cells for anti-cancer purposes. In general, control of cell fate and behaviours in these three-dimensional (3D) microenvironments has become the central aim for hydrogel-mediated cell delivery, towards which various models based on hydrogels and their hybrids have emerged. In this paper, we will first review the development of strategies aiming to overcome the aforementioned two ‘shortcomings’ by (i) establishing ADC survival and (ii) creating space for tissue formation respectively, and then introduce how people take advantage of these ‘disadvantages’ of hydrogel encapsulation for (iii) an enhanced confinement of cell motion. [Copyright &y& Elsevier]

Abstract: Using the material technique recently developed by us, we prepared a micropattern on poly(ethylene glycol) (PEG) hydrogel to keep background resistant to cell adhesion for a long time, which made examination of differentiation of localized stem cells available. Our micropattern designed in this paper prevented or ensured contact between cells adhering in arginine-glycine-aspartic acid (RGD) microdomains, and thus afforded a unique way to study the effects of cell-cell contact on the lineage differentiation of stem cells while ruling out the interference of soluble factors or cell seeding concentration etc. As demonstration, mesenchymal stem cells derived from rats were examined in this study, and both osteogenic and adipogenic differentiations were found to be regulated by cell-cell contact. Isolated cells exhibited less significant differentiation than paired or aggregated cells. For those stem cells in contact, the extent of differentiation was fairly linearly related to the extent of contact characterized by coordination number. Additionally, we revealed the existence of some unknown cues besides gap junction responsible for such effects of cell-cell contact. [Copyright &y& Elsevier]

Abstract: In this paper the possibility to tailor degradation and protein release behavior of photopolymerized thermosensitive hydrogels is studied. The hydrogels consist of ABA triblock copolymer, in which the thermosensitive A-blocks are methacrylated poly(N-(2-hydroxypropyl)methacrylamide lactate)s and the B-block is poly(ethylene glycol) with molecular weight of 10 kDa. These hydrogels are prepared by using a combination of physical and chemical cross-linking methods. When a solution of a thermosensitive methacrylated p(HPMAm-lac)-PEG-p(HPMAm-lac) is heated above its cloud point a viscoelastic material is obtained, which can be stabilized by introducing covalent cross-links by photopolymerization. By varying the polymer concentration, hydrogels with different mechanical properties are formed, of which the cross-linking density, mesh size, swelling and degradation behavior can be tuned. It was demonstrated that the release rate of three model proteins (lysozyme, BSA and IgG, with hydrodynamic diameters ranging from 4.1 to 10.7 nm) depended on the protein size and hydrogel molecular weight between cross-links and was governed by the Fickian diffusion. Importantly, the encapsulated proteins were quantitatively released and the secondary structure and the enzymatic activity of lysozyme were fully preserved demonstrating the protein friendly nature of the studied delivery system. [Copyright &y& Elsevier]

Abstract: This paper presents the development of new pH-sensitive, amphiphilic and biocompatible hydrogels based on alginate-g-PCL, cross-linked with calcium ions to form beads, prepared for controlled delivery of poorly water-soluble drug. We have focused our study on the effect of the length of PCL chains (530 and 1250gmol−1). Swelling profiles obtained clearly indicated that these hydrogels swell slightly (10–14%) in a simulated gastric fluid (pH 1.2), and strongly (700–1300% before disintegration) in a simulated intestinal fluid (pH 6.8). In both media, rates of swelling were lower for beads based on amphiphilic derivatives than for alginate/Ca2+ ones due to the hydrophobic PCL grafts, and decreased when hydrophobic character increased. A model drug, theophylline, was entrapped into these hydrogels and release studies were carried out. The drug was protected in acidic fluid (only 14–20% of release for alginate-g-PCL hydrogel against 35% of release for alginate hydrogel during 350min). The drug is released completely in neutral fluid due to ion exchanges and disintegration of the hydrogel. PCL leads to decrease in the release kinetics in SIF (2h for alginate-g-PCL/Ca2+ beads against 1h for alginate/Ca2+ beads). It was demonstrated that the establishment of clusters inside beads by intramolecular interactions between PCL grafts of 530gmol−1 in salt media allowed to retain the drug and to slow down its release considerably. [Copyright &y& Elsevier]

Abstract: This paper is aimed to the macro- and microscopic characterisation of a scleroglucan–borax gel system eventually hosting model drugs. A rheological study was carried out, also as a function of temperature, on samples at different polymer concentrations in the presence and without guest model drug. Applying the generalised Maxwell model the mechanical spectra, showing the gel-like characteristics dependent on polymer concentration, were obtained. Flory’s theory and the equivalent network approach were applied to the rheological data in order to describe the molecular arrangement of the scleroglucan chains in the presence of borate ions with an estimation of the network mesh size, ξ. Diffusion experiments of three model drugs, with different van der Waals radius, allowed the determination of the diffusion coefficients. An evaluation of the network mesh size was also obtained by means of a modified free volume theory and a good agreement between the two sets of ξ values was found. [Copyright &y& Elsevier]

Sterculia gum has been used as a therapeutic agent to cure diverticulitis. Hydrogels developed from sterculia gum to release the therapeutic agent will be double curing in action. Therefore, in the present study, an attempt has been made to synthesize novel hydrogels for the release of the model drug ciprofloxacin, a drug for diverticulitis. This paper discusses the synthesis, characterization, and in vitro release of ciprofloxacin from drug-loaded hydrogels in solutions of different pHs and simulated gastric and intestinal fluid. A non-Fickian diffusion mechanism has been observed for the release of the drug from drug-loaded hydrogels. This article also discusses the mechanistic implications of the cross-linking of sterculia gum with methacrylamide in the presence of N,N′-methylenebisacrylamide (N,N′-MBAAm) cross-linker. [ABSTRACT FROM AUTHOR]