Drug release rate and anti-microbial effect of controlled-diffusion biopolymer membranes

In this study, a series of fibrous membranes made from cellulose acetate (CA) and polyester urethane (PEU) by co-electrospining or blend-electrospining were evaluated for drug release kinetics, in vitro anti-microbial activity and in vivo would healing performance when used as wound dressings. To stop common clinical infections, an antibacterial agent, Polyhexamethylene Biguanide (PHMB) was incorporated into e-spun fibres. The presence of CA in the wound healing membrane was found to improve hydrophilicity and permeability to air and moisture. The in vivo tests indicated that the addition of PHMB and CA considerably improved the wound healing efficiency. CA fibres became slightly swollen upon contacting with the wound exudates. It can not only speed up the liquid evaporation but also create a moisture environment for wound recovery. The drug release dynamics of membranes was controlled by the structure of membranes and component rations within membranes. The lower ration of CA:PEU retained the sound mechanical properties of membranes, and also reduced the boost release effectively and slowed down diffusion of antibacterial agent during in vitro tests. The controlled-diffusion membranes exert long-term anti-infective effect.

Biocompatible ionic liquid-biopolymer electrolyte-enabled thin and compact magnesium-air batteries.

With the surge of interest in miniaturized implanted medical devices (IMDs), implantable power sources with small dimensions and biocompatibility are in high demand. Implanted battery/supercapacitor devices are commonly packaged within a case that occupies a large volume, making miniaturization difficult. In this study, we demonstrate a polymer electrolyte-enabled biocompatible magnesium-air battery device with a total thickness of approximately 300 μm. It consists of a biocompatible polypyrrole-para(toluene sulfonic acid) cathode and a bioresorbable magnesium alloy anode. The biocompatible electrolyte used is made of choline nitrate (ionic liquid) embedded in a biopolymer, chitosan. This polymer electrolyte is mechanically robust and offers a high ionic conductivity of 8.9 × 10(-3) S cm(-1). The assembled battery delivers a maximum volumetric power density of 3.9 W L(-1), which is sufficient to drive some types of IMDs, such as cardiac pacemakers or biomonitoring systems. This miniaturized, biocompatible magnesium-air battery may pave the way to a future generation of implantable power sources.

Chiral organochlorosilanes derived from terpenes: diastereoselective hydrosilylation of methylene bicyclo[2.2.1]heptanes with HSiMenCln-2 (n=0-2)

The H₂PtCl₆ catalysed hydrosilylation of the terpenes (+)-α-fenchene (XI), (−)-2-methylene bornane (XII), (+)-camphene (XIII) and (−)-3-methylene fenchane (XIV) using HSiMe₂Cl or HSiMeCl₂ proceeds with high regioselectively and in some cases, with high diastereoselectivity. KF-assisted oxidation of the hydrosilylation products gives predominately endo-terpene alcohols. The alcohols have inverted endo/exo ratios to those formed by oxidative hydroboration. Reaction of XIV with HSiMe₂Cl or HSiMeCl₂ is accompanied by a clean rearrangement of the isocamphane skeleton into (+)-2-methylene bornane (XII) prior to hydrosilylation.

The hydrosilylation of α-fenchene, 2-methylene bornane, camphene and 3-methylene fenchane with chlorosilanes HSiMe_nCl_n − 2 (n=0–2) occurred with varying degrees of diastereoselectivity providing anti-Markovnikov product mixtures, in which the endo-isomers dominate over the exo-isomers. These mixtures were oxidized to give the corresponding terpene alcohols. 3-Methylene fenchane undergoes a rearrangement into 2-methylene bornane prior to hydrosilylation.

Potential antiarrhythmic and cardioprotective agents based on adenosine

N-Ethylcarboxamidoadenosine (12) was synthesised from adenosine (1) and the 6-chloro-2’,3’-O-isopropylidene-AT-ethylcarboxamidoadenosine (25) was synthesised from inosine (19). Employing molecular modelling techniques and the results from previous structure activity relationships it was possible to design and synthesise a N6-substituted N-ethylcarboxamidoadenosines which possessed an oxygen in the N6-substituent either in the form of an epoxide (which was obtained by cpoxidising an alkene with m-CPBA or dimethyldioxirane) or in the form of a cyclic ether as was the case for N6-((tetrahydro-2H--pyran--2-yl)methyl-N-ethylcarboxamidoadenosine (78). These compounds were tested for their biological activity at the A1 adenosine receptor by their ability to inhibit cAMP accumulation in DDT, MF2 cells. The EC50 values obtained indicated that the N6-(norborn-5-en-2-yl)-N-ethylcarboxamidoadenosines were the most potent. Of theseN6-(S-endo-norbrn-5-en-2-yI)-N-ethylcarboxaniidoadenosine (56) was the most potent (0.2 nM). N6-(exo-norborn-5-en-2-yl)-2-iodo-N-ethylcarboxamidoadenosine (79) was synthesised from guanosine (22) and was also evaluated for its potency at the A, receptor (24.8 ± 1.5 nM). At present 79 is being evaluated for its selectivity for the A1 receptor compared to the other three receptor subtypes (A2a, A2b, A3). A series of N6-(benzyl)-N-ethylcarboxamidoadenosines were synthesised with substitutions at the 4-position of the phenyl ring. Another series of compounds were synthesised which replaced the methylene spacer between the N6H and the N6-aromatic or lipophilic substituent The replacement groups -were carbonyl and trans-2- cyclopropyl moieties. The N6-acyl compounds were obtained by reacting 2’,3’-O- di(tert-butyldimethylsilyl)-AT-ethylcarboxamidoadenosinc (59) with the appropriate acid chloride and then deprotecting with lelrabutylammonium fluoride in tetrahydrofuran. The compound N6-(4-(1,2-dihydroxy)ethyl)benzyl-N- ethylcarboxamidoadenosine (125) was synthesised by the reaction of 4-(1,2-0- isopropylidene-ethyl)benzyl aminc (123) with 6-chloro-2,3-0-isopropylidene-N- ethylcarboxamidoadenosine (25). Compound 123 was synthesised from an epoxidation of vinylbenzyl phthalimide (118) followed by an acidic ring opening to yield the diol which was isopropylidenated to yield 4-(l,2-O-isopropylidene- elhyl)benzyl phlhalimide (122), It was hoped that the presence of the diol functionality in 125 would increase water solubility whilst maintaining potency at the A3 receptor.

Estimating prey accessibility for waders : a problem still to be solved

Estimating the accessible prey fraction for short-billed waders, we used a new sampling device - the sediment- plane( Desholme t al. 1998) - to record prey density of the uppermost benthos communities in softbottom habitats. In contrast to "ordinary"core-samplers, the sediment plane allows a relatively quick sampling of the uppermost layers of the sediment and, thus, it should allow a more reliable estimate of the accessible benthos community especially of vertically mobile prey organisms such as polychaetes. To assess its usefulness, we compared samples collected with the sediment-plane that took only the uppermost 3cm of the sediment with samples taken with a core-sampler. These investigations showed significant differences between the two sampling methods. In comparison with the corresponding layer of the core samples, we found significantly higher numbers and a higher biomass for at least four polychaete species (e.g. Ragworm Nereis diversicolor) in the plane samples.Therefore, we recommend the use of the sediment-plane when studying the accessible fraction for foraging waders especially when studying short-billed species.

The "refoldability" of selected proteins in ionic liquids as a stabilization criterion, leading to a conjecture on biogenesis

The folding of proteins is usually studied in dilute aqueous solutions of controlled pH, but it has recently been demonstrated that reversible unfolding can occur in other media. Particular stability is conferred on the protein (folded or unfolded) when the process occurs in ‘protic ionic liquids’ (pILs) of controlled proton activity. This activity (‘effective pH’) is determined by the acid and base components of the pIL and is characterized in the present study by the proton chemical shift of the N–H proton. Here we propose a ‘refoldability’ or ‘refolding index’ (RFI) metric for assessing the stability of folded biomolecules in different solvent media, and demarcate high RFI zones in hydrated pIL media using ribonuclease A and hen egg white lysozyme as examples. Then we show that, unexpectedly, the same high RFIs can be obtained in pIL media that are 90% inorganic in character (simple ammonium salts). This leads us to a conjecture related to the objections that have been raised to ‘primordial soup’ theories for biogenesis, objections that are based on the observation that all the bonds involved in biomacromolecule formation are hydrolyzed in ordinary aqueous solutions unless specifically protected. The ingredients for primitive ionic liquids (NH3, CO, HCN, CO2, and water) were abundant in the early earth atmosphere, and many experiments have shown how amino acids could form from them also. Cyclical concentration in evaporating inland seas could easily produce the type of ambient-temperature, non-hydrolyzing, media that we have demonstrated here may be hospitable to biomolecules, and that may be actually encouraging of biopolymer assembly. Thus a plausible variant of the conventional ‘primordial soup’ model of biogenesis is suggested.

Physical, chemical and biological characterization of membrane fouling

In this chapter, advanced characterization of membrane fouling as a diagnostic tool has been summarized to prevent membrane fouling. Physical, chemical and biological analyses as membrane autopsies are mainly utilized to better understand membrane foulant. The physical characterization gives structure, roughness, charge effect, strength and hydrophobicity of membrane fouling. The chemical methods provide qualitative and quantitative measurements of different inorganic and organic matter. The biological properties present the spatial biofilm distribution, structure of dominant microorganisms and isolation and identification of microorganisms. In addition, detailed membrane foulant types are reviewed in terms of structure, roughness, hydrophobicity, charge effect, strength, calcium, magnesium, aluminum, iron, silicate, particle, functional group, biopolymer, humic acid, polysaccharide, structural composition, biofilm structure, microorganism and foulant interaction.

Towards a framework for implementing individual funding based on an Australian case study

Although individual funding is increasingly being used around the globe as a mechanism to fund social care, its implementation is proving to be problematic and implementation strategies are not well developed. This paper proposes a framework for the successful introduction and implementation of individual funding programs based on the analysis of data collected in a qualitative case study conducted in an Australian not-for-profit disability agency over a 4-year period from 2003 to 2007. Data were gathered through participant observation and interviews with program participants and managers, and the findings were validated with those involved. Bronfenbrenner’s ecological systems theory is used to analyze the findings from a micro, meso, exo, and macro perspective. The following factors were found to be important for successful implementation: the meaningful involvement of the person with disability in decision-making; adequate resources; access to information and appropriate supports; suitable activities being available; knowledge of policies and procedures; policies ensuring oversight and responsible accountability; employment conditions for workers being safeguarded; and support for staff and managers to adjust to their new roles. Knowledge of effective implementation strategies is important for disability agencies and for governments promoting individual funding because this radically different funding arrangement requires new implementation strategies.

Spinning Carbon Nanotube-Gel Fibers Using Polyelectrolyte Complexation

Biopolymer-single walled carbon nanotube (SWNT)-biopolymer fibers were prepared using a continuous flow spinning approach. Polyelectrolyte complexation was facilitated by injecting a SWNT-biopolymer dispersion into a coagulation bath containing a biopolymer of opposite charge. We showed that the ability to spin fibers and their properties depend on processing conditions such as polyelectrolyte pH, sonolysis regime (conditions employed to disperse SWNT) and the order of adding the anionic and cationic biopolymer solutions. Maximizing the ionic nature through changes in the pH increased spin-ability, while combining a sonicated dispersion with an as-prepared (non-sonicated) polyelectrolyte solution allowed us to optimize sonolysis conditions while retaining spin-ability of fibers with smooth surface morphology. Addition of the cationic biopolymer-SWNT dispersion to the anionic biopolymer solution resulted in mechanical reinforcement with the increase in SWNT loading fraction. All fibers decreased their electrical resistance upon exposure to water vapor.

A simple microfluidic chip design for fundamental bioseparation

A microchip pressure-driven liquid chromatographic system with a packed column has been designed and fabricated by using poly(dimethylsiloxane) (PDMS). The liquid chromatographic column was packed with mesoporous silica beads of Ia3d space group. Separation of dyes and biopolymers was carried out to verify the performance of the chip. A mixture of dyes (fluorescein and rhodamine B) and a biopolymer mixture (10 kDa Dextran and 66 kDa BSA) were separated and the fluorescence technique was employed to detect the movement of the molecules. Fluorescein molecule was a nonretained species and rhodamine B was attached onto silica surface when dye mixture in deionized water was injected into the microchannel. The retention times for dextran molecule and BSA molecule in biopolymer separation experiment were 45 s and 120 s, respectively. Retention factor was estimated to be 3.3 for dextran and 10.4 for BSA. The selectivity was 3.2 and resolution was 10.7. Good separation of dyes and biopolymers was achieved and the chip design was verified.

Thermal and rheological characteristics of biobased carbon fiber precursor derived from low molecular weight organosolv lignin

In the present work, electrospinnability as well as thermal, rheological, and morphological characteristics of low molecular weight hardwood organosolv lignin, as a potential precursor for carbon fiber, was investigated. Submicromter biobased fibers were electrospun from a wide range of polymer solutions with different ratios of organosolv lignin to polyacrylonitrile (PAN). Rheological studies were conducted by measuring viscosity, surface tension, and electrical conductivity of hybrid polymer solutions, and used to correlate electrospinning behavior of solutions with the morphology of the resultant electrospun composite fibers. Using scanning electron microscopy (SEM) images, the solutions that led to the formation of bead-free uniform fibers were found. Differential scanning calorimetry (DSC) analysis revealed that lignin-based fibers enjoy higher decomposition temperatures than that of pure PAN. Thermal stability of the lignin-based fibers was investigated by thermogravimetric analysis (TGA) indicating a high carbon yield of above 50% at 600 °C, which is highly crucial in the production of low-cost carbon fiber. It was also observed that organosolv lignin synergistically affects thermal decomposition of composite fibers. A significant lower activation energy was found for the pyrolysis of lignin-derived electrospun fibers compared to that of pure PAN.

New dibutyltin(IV) ladders: syntheses, structures and, optimization and evaluation of cytotoxic potential employing A375 (melanoma) and HCT116 (colon carcinoma) cell lines in vitro

Synthesis and spectroscopic properties of seven new dibutyltin(IV) compounds of 2-{(E)-4-hydroxy-3-[(E)-4-(aryl)iminomethyl]phenyldiazenyl}benzoic acids (L(n)HH'; n=2-8) with general formula {[Bu2Sn(L(n)H)]2O}2 (1-7) are reported. The compounds were characterized by elemental analysis and by UV-Visible, fluorescence, IR, (1)H, (13)C and (119)Sn NMR spectroscopies. Solid state structures of dibutyltin(IV) compounds 1-3, 6 and 7 were accomplished from single crystal X-ray crystallography which reveal the common ladder-type structure with two endo- and two exo-Sn atoms. The redox properties of L(n)HH' (n=2-4, 7 and 8) and their diorganotin(IV) compounds 1-3, 6 and 7 were also investigated by cyclic voltammetry. In general, the dibutyltin(IV) derivatives exhibited significant in vitro cytotoxic potency towards A375 (melanoma) and HCT116 (colon carcinoma) cell lines as determined by several experiments, like Live and Dead assay, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) cell viability assay, LDH (lactate dehydrogenase), cleavage of caspases and PARP (poly(ADP-ribose)polymerase), and DNA fragmentation. Dibutyltin(IV) compounds increase cell death without cytolysis and decreases membrane fluidity, without interfering with p53. Among the dibutyltin(IV) compounds, compound 6 was found to be the most potent, with an IC50 value of 78nM. A mechanism of action for tumor cell death is proposed.