Nanoparticle Network Formation in Nanostructured and Disordered Block Copolymer Matrices

Incorporation of nanoparticles composed of surface-functionalized fumed silica (FS) or native colloidal silica (CS) into a nanostructured block copolymer yields hybrid nanocomposites whose mechanical properties can be tuned by nanoparticle concentration and surface chemistry. In this work, dynamic rheology is used to probe the frequency and thermal responses of nanocomposites composed of a symmetric poly(styrene-b-methyl methacrylate) (SM) diblock copolymer and varying in nanoparticle concentration and surface functionality. At sufficiently high loading levels, FS nanoparticle aggregates establish a load-bearing colloidal network within the copolymer matrix. Transmission electron microscopy images reveal the morphological characteristics of the nanocomposites under these conditions

Conjugation with L, L-diphenylalanine Self-Assemblies Enhances In Vitro Antitumor Activity of Phthalocyanine Photosensitizer

We present the synthesis and characterization of new peptide conjugates obtained by hierarchical co-assembly of L,L-diphenylalanine (FF) and zinc phthalocyanine complexes (ZnPc) in water. Self-assembly capabilities under defined conditions were investigated by scanning electron microscopy, and photophysical properties were evaluated using UV-Vis and fluorescence spectroscopy. AFM observations demonstrated that these ZnPcs form different highly ordered arrays on the crystalline faces of the FF microplates and that surface roughness significantly changes with the presence of differently substituted phthalocyanine units. XRD assays showed that the overall molecular packing of the conjugates is organized according to a hexagonal symmetry, with ZnPcs hosted in the interstices of the peptide phase. In vitro photodynamic studies were conducted on human breast cancer MCF-7 cells to investigate both cellular uptake and cytotoxicity. It was shown that FF self-assemblies are not toxicity and enhance accumulation of ZnPc in MCF-7 cells, improving apoptotic cell death upon irradiation. Our findings demonstrate enhancement of ZnPc antitumor efficiency by FF conjugates and a proof-of-concept for new photosensitizer carriers based on peptide conjugates

Determinants of the range of drugs prescribed in general practice: a cross-sectional analysis

Background: Current health policies assume that prescribing is more efficient and rational when general practitioners (GPs) work with a formulary or restricted drugs lists and thus with a limited range of drugs. Therefore we studied determinants of the range of drugs prescribed by general practitioners, distinguishing general GP-characteristics, characteristics of the practice setting, characteristics of the patient population and information sources used by GPs. Methods: Secondary analysis was carried out on data from the Second Dutch Survey in General Practice. Data were available for 138 GPs working in 93 practices. ATC-coded prescription data from electronic medical records, census data and data from GP/ practice questionnaires were analyzed with multilevel techniques. Results: The average GP writes prescriptions for 233 different drugs, i.e. 30% of the available drugs on the market within one year. There is considerable variation between ATC main groups and subgroups and between GPs. GPs with larger patient lists, GPs with higher prescribing volumes and GPs who frequently receive representatives from the pharmaceutical industry have a broader range when controlled for other variables. Conclusion: The range of drugs prescribed is a useful instrument for analysing GPs' prescribing behaviour. It shows both variation between GPs and between therapeutic groups. Statistically significant relationships found were in line with the hypotheses formulated, like the one concerning the influence of the industry. Further research should be done into the relationship between the range and quality of prescribing and the reasons why some GPs prescribe a greater number of different drugs than others.

Pharmaceutical care and its relationship to prescribing behaviour of general practitioners.

Contains fulltext : 50980.pdf (publisher's version ) (Closed access)OBJECTIVE: To study the correlation between pharmaceutical care and prescribing routines of general practitioners (GPs). METHODS: Cross-sectional study; 201 pharmacies, 408 general practices, The Netherlands, 2000/2001. The variation in prescribing behaviour was characterised using 20 validated prescribing indicators based on general practice guidelines. The general construct 'adherence to guidelines' served as the dependent variable and was formed by summing the scores of the prescribing indicators. Four possible determinants of the variation were determined on the basis of survey questions: the construct 'the pharmacist's attitude towards pharmaceutical care', and three partial constructs derived from the pharmacist's care-providing function: the care for the individual patient, the cooperation with general practitioners and the registration of the care provided. A multiple linear regression analysis was then performed. MAIN OUTCOME MEASURE: The weighted score for the prescribing indicators. RESULTS: The weighted average score for the prescribing indicators was 65% (SD 3.7). The response rate to the survey was 71%. The pharmacist's attitude to pharmaceutical care, as well as the degree to which the pharmacist provided care for the individual patient, the degree to which he cooperated with the general practitioner and the degree to which he registered the care provided were not correlated with the 'adherence to guidelines' by the general practitioner with whom the pharmacist frequently cooperated. CONCLUSION: Variations between general practitioners in the quality of prescribing, as measured by their adherence to guidelines, were not correlated with pharmaceutical care by the pharmacist with whom they cooperated on a day-to-day basis