A mild and quantitative route towards well-defined strong anionic/hydrophobic diblock copolymers:Synthesis and aqueous self-assembly

Block copolymers that accommodate both hydrophobic and ionic elements are interesting materials for numerous applications, such as stabilizing agents, lubricants and proton-exchange membranes. Frequently these copolymers are based on weak polyelectrolytes, but the pH-dependent charge density restricts their use to a limited pH window. Although strong polyelectrolytes do not suffer this problem, the most commonly employed post-modification approach limits the choice of the hydrophobic component, as harsh reaction conditions are usually involved. Moreover, this method often results in incomplete functionalization of the precursor copolymer. To avoid these difficulties a mild route was developed that is based on a hydrophobic protected poly(3-sulfopropyl methacrylate) intermediate that enables the preparation of well-defined strong anionic polyelectrolytes. The potential of this method was demonstrated by synthesizing hydrophobic/strong anionic diblock copolymers, and their self-assembly in aqueous solution was studied

Balancing Enzyme Encapsulation Efficiency and Stability in Complex Coacervate Core Micelles

Encapsulation of charged proteins into complex coacervate core micelles (C3Ms) can be accomplished by mixing them with oppositely charged diblock copolymers. However, these micelles tend to disintegrate at high ionic strength. Previous research showed that the addition of a homopolymer with the same charge sign as the protein improved the stability of protein-containing C3Ms. In this research, we used fluorescence correlation spectroscopy (FCS) and dynamic light scattering (DLS) to study how the addition of the homopolymer affects the encapsulation efficiency and salt stability of the micelles. We studied the encapsulation of laccase spore coat protein A (CotA), a multicopper oxidase, using a strong cationic-neutral diblock copolymer, poly(N-methyl-2-vinyl-pyridinium iodide)-block-poly(ethylene oxide) (PM2VP128-b-PEO477), and a negatively charged homopolymer, poly(4-styrenesulfonate) (PSS215). DLS indeed showed an improved stability of this three-component C3M system against the addition of salt compared to a two-component system. Remarkably, FCS showed that the release of CotA from a three-component C3M system occurred at a lower salt concentration and over a narrower concentration range than the dissociation of C3Ms. In conclusion, although the addition of the homopolymer to the system leads to micelles with a higher salt stability, CotA is excluded from the C3Ms already at lower ionic strengths because the homopolymer acts as a competitor of the enzyme for encapsulation

Translocation of positively and negatively charged polystyrene nanoparticles in an in vitro placental model

AbstractTo obtain insight in translocation of nanoparticles across the placental barrier, translocation was studied for one positively and two negatively charged polystyrene nanoparticles (PS-NPs) of similar size in an in vitro model. The model consisted of BeWo b30 cells, derived from a human choriocarcinoma grown on a transwell insert forming a cell layer that separates an apical from a basolateral compartment. PS-NPs were characterized with respect to size, surface charge, morphology and protein corona. Translocation of PS-NPs was not related to PS-NP charge. Two PS-NPs were translocated across the BeWo transwell model to a lower extent than amoxicillin, a model compound known to be translocated over the placental barrier to only a limited extent, whereas one PS-NP showed a slightly higher translocation. Studies on the effect of transporter inhibitors on the translocation of the PS-NPs indicated that their translocation was not mediated by known transporters and mainly dependent on passive diffusion. It is concluded that the BeWo b30 model can be used as an efficient method to get an initial qualitative impression about the capacity of NPs to translocate across the placental barrier and set priorities in further in vivo studies on translocation of NPs to the fetus

Rapid and Quantitative De-tert-butylation for Poly(acrylic acid) Block Copolymers and Influence on Relaxation of Thermoassociated Transient Networks

The synthesis of charged polymers often requires the polymerization of protected monomers, followed by a polymer-analogous reaction to the polyelectrolyte product. We present a mild, facile method to cleave tert-butyl groups from poly(tert-butyl acrylate) blocks that yields poly(acrylic acid) (pAA) blocks free of traces of the ester. The reaction utilizes a slight excess of HCl in hexafluoroisopropanol (HFIP) at room temperature and runs to completion within 4 h. We compare deprotection in HFIP with the common TFA/DCM method and show that the latter does not yield clean pAA. We show the effect of complete tert-butyl cleavage on a ABA triblock copolymer, where poly(N-isopropylacrylamide) (pNIPAM) is A and pAA is B, by means of viscosimetry, DLS, and SAXS on solutions above overlap. The pNIPAM blocks dehydrate, and their increased self-affinity above the lower critical solution temperature (LCST) results in network formation by the triblocks. This manifests itself as an increase in viscosity and a slowing down of the first-order correlation function in light scattering. However, this stickering effect manifests itself exclusively when the pAA block is tert-butyl-free. Additionally, SAXS shows that the conformational properties of tert-butyl-free pAA copolymers are markedly different from those with residual esters. Thus, we illustrate a surprising effect of hydrophobic impurities that act across blocks and assert the usefulness of HCl/HFIP in pAA synthesis

PERANAN WEBSITE DALAM AKTIVITAS PUBLIC RELATIONS SEBAGAI MEDIA PENGHUBUNG ANTARA MASYARAKAT DAN PEMERINTAH DI DISHUBKOMINFO KARANGANYAR

SUMMARY Ni Nyoman Ayu A.W, D1613067, Public Relations, Utilization Website Functions in Public Relations Activities as Media Communicator between the Community and the Government in Dishubkominfo Karanganyar, 2016. Kuliah Kerja Media (KKM) or we called Job Training do it by the author in Dishubkominfo Karanganyar. The reason why the author chose Dishubkominfo Karanganyar as a job training (KKM) in the field of communication and information technology, especially because it looks a lot of public relations activities or practice public speaking especially between government Karanganyar Regent and his Deputy with a lot of community. Here Public Relations is a communication method that is where the various forms of communication. Which in Punlic Relations that there is an attempt to realize the harmonious relationship between an organization and its publics. Public Relations is a deliberate effort, planned on an on going basis to create mutual understanding between an institution / organization with the public. Public Relations can also be regarded as an art as well as social science of analyzing trends, predicting their consequences, briefed the leaders of the institution / organization and implementing planned programs to meet the interests of both the institution / organization and the people involved. At the time of the job training writers do a lot of practice public relations or public relations starting from routine activities for official that morning assembly, socializing with office workers, mutual coordination with staff-related staff, and lobbied with related parties participating in activities , documenting coverage and must maintain good relations between the internal and external Dishubkominfo Karanganyar District. Even job training is very useful for writing because it can prepare for the world of work that requires professional workers and authors directly to gain knowledge related to the field of public relations in order practices. Based on reports from the job training the institution Dishubkominfo Karangayar District, the authors conclude that public relations activities are vital to maintaining good relations between the internal and external Dishubkominfo Karanganyar District

Quantification of energy input required for chitin nanocrystal aggregate size reduction through ultrasound

Nanoparticles have been claimed to contribute efficiently to e.g. the mechanical strength of composite materials when present as individual particles. However, these particles tend to aggregate. In this paper we prepare nanocrystals from chitin, a product with high potential added value for application in bio-based materials, and investigate the effect of ultrasound on de-aggregation. Chitin nanocrystals with a length ~ 200 nm and a diameter ~ 15 nm, were obtained via acid hydrolysis of crude chitin powder. Freeze drying resulted in severe aggregation and after redispersion sizes up to ~ 200 µm were found. Ultrasound treatment was applied and break up behaviour was investigated using static light scattering, dynamic light scattering, and laser diffraction. Our results suggest that the cumulative energy input was the dominant factor for chitin nanocrystal aggregate breakup. When a critical energy barrier of ~ 100 kJ/g chitin nanocrystals was exceeded, the chitin nanocrystal aggregates broke down to nanometre range. The break up was mostly a result of fragmentation: the aggregation energy of chitin nanocrystal aggregates was quantified to be ~ 370 kJ/g chitin nanocrystals and we hypothesize that mainly van der Waals interactions and hydrogen bonds are responsible for aggregation

Bovine beta-casein micelles as delivery systems for hydrophobic flavonoids

The milk protein β-casein (β-CN) is an intrinsically unstructured amphiphilic protein that self-assembles into micelles. Naringenin is the main hydrophobic flavanone in grapefruit and has several beneficial biological effects: it exhibits, for example, antioxidant, anticancer and anti-inflammatory activity. This paper shows that naringenin can be encapsulated in β-CN micelles. Fluorescence spectroscopy, molecular docking modelling, dynamic light scattering (DLS), static light scattering (SLS) and isothermal titration calorimetry (ITC) were applied to characterize the effect of naringenin on the protein association behavior and properties of the resulting micelles. Naringenin binds to β-CN at both pH 7 and pH 2, promotes the formation of micelles with a well-defined size distribution and stabilizes the micelles. It was found that naringenin-containing β-CN micelles have a lower critical micelle concentration (CMC) and a larger aggregation number (Nagg) compared to pure β-CN micelles. SLS and multi-angle DLS results suggest considerable differences between the structures of pure β-CN micelles and naringenin-containing β-CN micelles. In the presence of naringenin spherical micelles were formed with a relatively loose core (“hollow sphere”), while the pure β-CN micelles are smaller and seem to be elliptic. Notably, by uptake of naringenin in the micelles, the concentration of naringenin in aqueous solution could be raised considerably. These findings lead to the conclusion that β-CN micelles are very promising as effective delivery nano-vehicles for hydrophobic bioactive compounds.</p