Endothelialisation and cell retention on gelation-chitosan coated electrospun polyurethane, poly (lactide-co-glycolide) and collagen-coated pericardium

Arterial bypass and heart valve replacements are two of the most common surgical treatments in cardiovascular surgery today. Currently, artificial materials are used as substitute for these cardiac tissues. However, these foreign materials do not have the ability to grow, repair or remodel and are thrombogenic, leading to stenosis. With the aid of tissue engineering, it is possible to develop functional identical copies of healthy heart valves and arteries, which are biocompatible. Although much effort has been made into this area, there are still inconsistencies with respect to
endothelialisation and cell retention on synthetic biological grafts. These variations may be attributed to differences in factors such as cell seeding density, incubation periods and effects of shear stress. In this study, we have compared the endothelialisation and cell retention between gelain chitosan-coated electrospun polyurethane (PU), poly (lactide co-glycolide) (PGA/PLA) and collagen-coated pericardium. Endothelial cells adhered to all of the materials as early as 1–day post seeding. After 7-day of seeding, the coverage on PU was almost 45% and that on PGA/PLA was about 25% and the least was on collagen-coated pericardium of approximately 15%. It was observed that the PU showed superior cell coverage and cell retention in comparison to the PGA/PLA and collagen-coated pericardium.

The miscibility of poly(d,l-lactide-co-glycolide) with amphiphilic molecules and the interaction of their mixtures with DNA at air/water interface

The miscibility of poly(d,l-lactide-co-glycolide) (PLG) with three amphiphilic molecules and the interaction of the PLG/surfactant mixtures with DNA at air/water interface are investigated by π-A isotherms, Brewster angle microscopy (BAM) and atomic force microscopy (AFM) techniques. The π-A isotherms of the PLG mixtures with cationic C12AzoC6PyBr, and C12AzoC6N(CH3)3Br, are quite different from the π-A isotherm of pure PLG on water subphase. In contrast to the case, the π-A isotherm of PLG mixed with nonionic C12AzoC6OPy is almost identical to the pure PLG except some increasing of molecular area. Similar phenomena are observed on DNA subphase. The in situ BAM and ex situ AFM observations demonstrate that the dispersion of PLG at air/water interface becomes good when it mixes with the two cationic surfactants, whereas quite poor due to the phase separation when it mixes with the nonionic amphiphilic molecule. Based on these results we conclude that the cationic surfactants can affect the conformation change of PLG at air/water interface and figure a well miscibility with polymer whereas the nonionic amphiphilic molecule presents poor miscibility. In addition, the even mixing of the PLG and the cationic surfactants is favorable for the adsorption to DNA more effectively.

Monolayer behavior of a pyridyl head-group-containing amphiphile and its miscibility with poly(D,L-lactide-co-glycolide) on different pH subphase

In this paper, we investigated the Langmuir film and Langmuir–Blodgett (LB) monolayer film of a nonionic amphiphilic molecule, 4-(6-p-pyridyloxyl)hexyloxyl-4′-dodecyloxylazobenzene (C12AzoC6Py) and its mixture with poly(d,l-lactide-co-glycolide) (PLG) at different subphase pH values (2.0, 2.6, 3.3, 4.4, and 6.5, respectively) by surface pressure–area (π–A) isotherms, in situ interface Brewster angle microscopy (BAM), and ex situ atomic force microscopy (AFM). For pure C12AzoC6Py, its π–A isotherms display a plateau when the subphase pH value is lower than 3.0. The pressure of the plateau increases with the decrease of pH until 2.0. Over the plateau, the π–A isotherms become almost identical to the one under neutral conditions. The appearance of such a plateau can be explained as the coexistence of protonation and unprotonation of pyridyl head groups of the employed amphiphile. In contrast to the homogeneous surface morphology of pure C12AzoC6Py near the plateau by BAM observation, the surface in the case of its mixing with PLG exhibits a dendritic crystalline state under low surface pressure at subphase pH lower than 3.0. The crystalline state becomes soft and gradually melts into homogeneous aggregates with surface pressure increasing to a higher value than that of the plateau. Meanwhile, the hydrolysis of PLG in the mixture system at the interface has been affirmed to be restrained to a very large extent. And the PLG was believed to be compelled to the up layer of the LB film due to the phase separation, which is examined by AFM. Based on the experimental results, the corresponding discussion was also performed.

Formulation optimization for high drug loading colonic drug delivery carrier

High drug loading (DL) carrier is an effective way to cure the cancerous cells. High drug loading is also one of the key issues in the drug delivery research, especially the colonic drug delivery system by oral administration. The times of drug intake could be remarkably reduced if high drug loading carriers are administered. At the same time, the related formulation materials could be effectively utilized. One major obstacle with the preparation of this system is the difficulty to encapsulate the hydrophilic drug into hydrophobic encapsulation polymer. A design of high drug loading delivery system with biodegradable, biocompatible materials and optimization of the fabrication process is a potential solution to solve the problem. So in this research, 5-Fluorouracil (5-FU) loaded Poly (lactide-co-glycolide) (PLGA) nanoparticles were prepared by double emulsion and solvent evaporation method. Several fabrication parameters including theoretical drug loading, volume ratio of outer water phase to the first emulsion, pH value of outer aqueous phase and emulsifier PVA concentration were optimized to get a high drug loading nanoparticles. The result shows that with the increase of theoretical drug loading, the actual drug loading increased gradually. When adjusted the pH value of outer aqueous phase to the isoelectric point (8.02) of 5-Fluorouracil, the drug loading exhibited a higher one compared to other pH value solution. Relative higher volume ratio of outer water phase to the first emulsion was also beneficial for the enhancement of drug loading. But the nanoparticles size increased simultaneously due to the lower shearing force. When increased the PVA concentration, the drug loading showed an increase first and following a drop.

Nurses and personal attendants' diabetes knowledge : in regional public residential care

Aim: Identify staff knowledge about diabetes medicines and organisational factors that influence safe medicines use in two large Australian regional public RACs that comply with national accreditation standards.

Background: Diabetes management is complicated in residential aged care facilities (RAC). Managing medicines is complex, especially in older people. Little is known about diabetes-specific medicine knowledge of various care staff (registered nurses (RN), enrolled nurses (EN) and patient care attendants (PCA) working in RAC.

Methods: A triangulation of methods was used to collect the data: anonymous self-complete questionnaire (ADKnowl) staff interviews to clarify practice issues that could affect safe medicine use, and a case file audit to identify medicine-related data. Questionnaires were distributed to all RNs, ENs and PCAs in the two services via nursing management (N=540). The ADKnowl was supplemented with additional questions and vignettes derived from actual case notes in each RAC to assess translation of knowledge into practice. Only medicine related data are reported.

Results: Sixty-eight people returned completed questionnaires (12.5% response rate). Knowledge deficits were identified in administering oral hypoglycaemic agents and insulin, their action and potential adverse events. Most ENs and PCAs did not know why HbA1c was measured. Almost half the RNs and ENs and 80% of PCAs did not know how diabetes comorbidities affect medicine choices. RN achieved higher overall average knowledge scores,74.3%, compared to ENs and PCA, 49%. The interviews suggest lack of time, unclear communication processes, inadequate knowledge about medications and resident behaviour compromises optimal medicine administration. Twenty case files audits were undertaken in each RAC and revealed residents were taking on average nine medicines.

Conclusion: Staff involved in caring for residents with diabetes had suboptimal general and medicine-specific diabetes knowledge to deliver optimal care. System issues and unpredictable resident behaviours made medicine management difficult and compromised safety.

Overcoming interfacial affinity issues in natural fiber reinforced polylactide biocomposites by surface adsorption of amphiphilic block copolymers

This work demonstrates that the interfacial properties in a natural fiber reinforced polylactide biocomposite can be tailored through surface adsorption of amphiphilic and biodegradable poly (ethylene glycol)-b-poly-(L-lactide) (PEG-PLLA) block copolymers. The deposition from solvent solution of PEG-PLLA copolymers onto the fibrous substrate induced distinct mechanisms of molecular organization at the cellulosic interface, which are correlated to the hydrophobic/hydrophilic ratios and the type of solvent used. The findings of the study evidenced that the performance of the corresponding biocomposites with polylactide were effectively enhanced by using these copolymers as interfacial coupling agents. During the fabrication stage, diffusion of the polylactide in the melt induced a change in the environment surrounding block copolymers which became hydrophobic. It is proposed that molecular reorganization of the block copolymers at the interface occurred, which favored the interactions with both the hydrophilic fibers and hydrophobic polylactide matrix. The strong interactions such as intra- and intermolecular hydrogen bonds formed across the fiber−matrix interface can be accounted for the enhancement in properties displayed by the biocomposites. Although the results reported here are confined, this concept is unique as it shows that by tuning the amphiphilicity and the type of building blocks, it is possible to control the surface properties of the substrate by self-assembly and disassembly of the amphiphiles for functional materials.

Chitosan-modified PLGA nanoparticles with versatile surface for improved drug delivery

Shortage of functional groups on surface of poly(lactide-co-glycolide) (PLGA)-based drug delivery carriers always hampers its wide applications such as passive targeting and conjugation with targeting molecules. In this research, PLGA nanoparticles were modified with chitosan through physical adsorption and chemical binding methods. The surface charges were regulated by altering pH value in chitosan solutions. After the introduction of chitosan, zeta potential of the PLGA nanoparticle surface changed from negative charge to positive one, making the drug carriers more affinity to cancer cells. Functional groups were compared between PLGA nanoparticles and chitosan-modified PLGA nanoparticles. Amine groups were exhibited on PLGA nanoparticle surface after the chitosan modification as confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The modified nanoparticles showed an initial burst release followed by a moderate and sustained release profile. Higher percentage of drugs from cumulative release can be achieved in the same prolonged time range. Therefore, PLGA nanoparticles modified by chitosan showed versatility of surface and a possible improvement in the efficacy of current PLGA-based drug delivery system.

Nanofibrillar micelles and entrapped vesicles from biodegradable block copolymer/polyelectrolyte complexes in aqueous media

Here we report a viable route to fibrillar micelles and entrapped vesicles in aqueous solutions. Nanofibrillar micelles and entrapped vesicles were prepared from complexes of a biodegradable block copolymer poly(ethylene oxide)-block-poly(lactide) (PEO-b-PLA) and a polyelectrolyte poly(acrylic acid) (PAA) in aqueous media and directly visualized using cryogenic transmission electron microscopy (cryo-TEM). The self-assembly and the morphological changes in the complexes were induced by the addition of PAA/water solution into the PEO-b-PLA in tetrahydrofuran followed by dialysis against water. A variety of morphologies including spherical wormlike and fibrillar micelles, and both unilamellar and entrapped vesicles, were observed, depending on the composition, complementary binding sites of PAA and PEO, and the change in the interfacial energy. Increasing the water content in each [AA]/[EO] ratio led to a morphological transition from spheres to vesicles, displaying both the composition- and dilution-dependent micellar-to-vesicular morphological transitions.

Do renal access coordinators make a difference? What is the evidence?

Background
Since the introduction of the renal access coordinator (RAC) role into Australia there have been only anecdotal examples of associated improvements in patient outcome and service delivery and scant published quantitative extant evidence exists.

Aim
To review the literature related to the impact of RACs on dialysis patient outcomes and associated service delivery, gauge the level of evidence available and identify gaps in the literature.

Method
A three stage Joanna Briggs Institute (JBI) systematic review process was used to collect and synthesise data. The review considered studies that explored and measured the RAC role in the adult haemodialysis context. All quantitative study designs were considered. Due to lack of homogeneity a narrative synthesis was undertaken.

Results
Five studies met the inclusion criteria for the review. All studies included multidisciplinary teams with variable emphasis on the RAC role. Four pre post intervention cohort studies measured incident and/or prevalent AVF, AVG and CVC rates in the haemodialysis population and the quality assurance report measured differences in patency rates between AVF and AVG and associated hospital length of stay. All discussed the role of central coordination as a contributor to the success of vascular access care.

Conclusion
The available reports do suggest an association between RACs and improved patient outcomes. These improved patient outcomes were apparent in an increase in incident and prevalent AVFs, and a decrease in the incidence and prevalence of CVCs. Both associations are correlated with a reduction in infection rates, length of hospital stay and healthcare costs
 

Multifunctional nanoparticle-EpCAM aptamer bioconjugates: a paradigm for targeted drug delivery and imaging in cancer therapy

The promising proposition of multifunctional nanoparticles for cancer diagnostics and therapeutics has inspired the development of theranostic approach for improved cancer therapy. Moreover, active targeting of drug carrier to specific target site is crucial for providing efficient delivery of therapeutics and imaging agents. In this regard, the present study investigates the theranostic capabilities of nutlin-3a loaded poly (lactide-co-glycolide) nanoparticles, functionalized with a targeting ligand (EpCAM aptamer) and an imaging agent (quantum dots) for cancer therapy and bioimaging. A wide spectrum of in vitro analysis (cellular uptake study, cytotoxicity assay, cell cycle and apoptosis analysis, apoptosis associated proteins study) revealed superior therapeutic potentiality of targeted drug loaded NPs over other formulations in EpCAM expressing cells. Moreover, our nanotheranostic system served as a superlative bio-imaging modality both in 2D monolayer culture and tumor spheroid model. Our result suggests that, these aptamer-guided multifunctional NPs may act as indispensable nanotheranostic approach toward cancer therapy.