Potentiometric detection of polyions based on functionalized magnetic nanopaiticles

A novel potentiometric detection strategy based on functionalized magnetic nanoparticles has been developed for rapid and sensitive sensing of polyions.Highly dispersed magnetic nanoparticles coated with ion exchanger and plasticizer could promote an in situ cooperative ion-pairing interaction between the ion exchanger and the polyion analyte in sample solution by dramatically reducing the mass-transfer distance.With applying a magnetic field,the nanoparticles can be attached to the surface of ion exchanger free polymeric membrane.The observed potential signals are related to the polyion concentrations.The proposed polymeric membrane electrode exhibits a linear relationship between the greatest potential response slope（dE/dt） and the logarithm of protamine concentration in the range of 0.05-5μg/mL with a lower detection limit of 0.033μg/mL.

A Preliminary Study of Rotundine-Polyion Complex Release System

A rotundine-polyion complex(PIC)release system was prepared first by granulation of rotundine containing chitosan acetate solution and then by complexing with carboxymethyl glucomannan(CMGM)solution on the granular surface.The granules have an average diameter of 1.38-1.53 mm and the drug content reaches 62.89％.The external release tests showed T_(50) to be 45 rain and the total release time 4 h in an artificial gastric juice,while no more than 60％ of the drug was released in the same period of time in an ar- tificial intestinal fluid.The various factors affecting the external release were examined.

An Efficient Extraction-Free Method for Oxidative Desulfurization of Model Fuels Employing Cross-Linked Polyionic Liquid Phosphotungstate Catalysts

An efficient extraction-free oxidative desulfurization(ODS)process using a series of cross-linked polyionic liquid phosphotungstate(CLPIL-PW)catalysts is reported.The cross-linked PILs were prepared with DVB and 1-n-alkyl-3-vinyl imidazole hydrobromide(alkyl=ethyl,butyl,octyl,dodecyl),and were then assembled with phosphotungstic acid(H_(3)PW_(12)O_(40))to form the catalysts.The CLPIL-PWs have been applied to the oxidative removal of dibenzothiophene(DBT)from model oil with H_(2)O_(2) as an oxidant.The effects of ionic liquid(IL)cationic species,varying the DVB/IL molar ratio in the polymerization process,and varying operating conditions were investigated.The CLPIL-PWs were characterized by inductively coupled plasma(ICP)mass spectrometry,elemental analysis,scanning electron microscopy(SEM),Fourier transform infra-red(FTIR)spectroscopy,X-ray diffraction(XRD),^(13)C and^(31)P nuclear magnetic resonance(NMR)spectroscopy.The polydivinylbenzene-co-1-n-octyl-3-vinyl imidazole phosphotungstate(P(DVB-OVIm)PW)exhibited the highest DBT removal efficiency(99.9%)and remarkable recyclability,and could be reused eight times without reducing its activity.Finally,an extraction-free ODS mechanism is proposed.

Electroredox Behavior of Novel Poly viol ogens Modified Electrodes

The electroredox behavior of novel modified electrodes coated with complexes of different polyviologens was investigated using cyclic voltammetry. The influences of compositions of electrolyte complex on the reversibility of the modified electrode and the electrochromic properties were studied also. It was found that all the ratios of integrated charges of cathodic to anodic scan (Qc/QA) are close to 1, which indicates that these modified electrodes have good reversible behavior. Repeated stepping over the first wave for 500 scans, the PSS-PX(p)V modified electrode showed excellent stability. The first reduction potential (E1), decrease of current height (Dec%), response time (tre tox) of various polyviologen modified electrodes were reported. In addition, the effect of the coverage of polyviologen on the electrode surface was also examined. The rate of electron transfer in this heterogeneous system is diffusion-controlled, consistent with the Conttrell equation.

Reversibly size-switchable polyion complex micelles for antiangiogenic cancer therapy

Size is one of the most important characteristics of nanoparticles to influence their biodistribution and antitumoral efficacy.Particles with large sizes have difficulty in deep tumor penetration,while small particles are easily removed from tumor tissues due to the high tumor interstitial fluid pressure.To address these issues,an intelligent core-crosslinked polyion complex micelle(cPCM)with a reversibly sizeswitchable feature was engineered in this study.The micelles are consisting of methoxy poly(ethylene glycol)-poly(D,L-lactide)copolymer(mPEG-PLA),mPEG-PLA-(HE)6CC,and mPEG-PLA-(RG)6CC at an optimal mass ratio of 6:1:1 with an antiangiogenic compound,dabigatran etexilate(DE),encapsulated.The net charge inside the micelles is switchable when exposed to different pH conditions,thereby leading to revisable size-change of micelles.DE-loaded micelles(DE@cPCM)can swell and release drugs at the tumor sites with a mildly acidic pH,while they shrink and protect the cargo from leaking into the blood circulation with a neutral pH.Results indicated that DE@cPCM can inhibit tumor angiogenesis in vitro and in vivo,thereby efficiently restraining tumor growth in a 4T1-bearing mouse model.Collectively,the sizeswitchable cPCM is a promising nanoplatform for targeting delivery of anticarcinogens into the matrix of tumor tissues.

A novel polyionic liquid with lubricity and viscosity-increasing dual functionalities as the additive in aqueous lubrication system

The polyionic liquid poly-PEGMA-r-METAC(PPM)with quaternary ammonium has been synthesized and evaluated as additive in aqueous lubricating fluids.The rheological behavior of aqueous lubricating fluids with PPM has been characterized to confirm PPM’s function as a viscosity modifier.The tribological behavior of aqueous lubricating fluids with PPM has been investigated on SRV-V and MTM testing machines.It was found that PPM has excellent viscosity-increasing,lubricating,and anti-wear properties as an additive for aqueous,which can be attributed to the ability of PPM to form the protective film and boundary tribofilm generated from complex tribochemical reaction on rubbing surface.The obtained PPM with dual functions of anti-corrosion additives and viscosity index improver can play an important role in diverse lubrication regimes.

An antistatic agent based on polyionic liquid applied to nylon 6

In order to improve the electrical conductivity of nylon 6(PA6)and avoid misfires and explosions caused by static charge accumulation,a quaternary ammonium salt polyionic liquid(PIL)antistatic agent was synthesized in this paper.The surface resistance of PA6 was reduced to 10~8Ωwith the addition of 2 wt%antistatic agent,and the mechanical properties and aging resistance of the substrate were improved.Meanwhile,the morphology and crystallinity of PIL/PA6 composites were further characterized by scanning electron microscope(SEM),energy dispersion spectrometer(EDS)and X-ray diffraction(XRD).It is worth noting that the quaternary ammonium salt polyionic liquid antistatic agent synthesized in this paper has the advantages of excellent antistatic effect,durability,low cost,and simple reaction condition,so it has a broad application prospect in the antistatic aspect of PA6.

Self-assembled structures of a semi-rigid polyanion in aqueous solutions and hydrogels

Poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT), a kind of liquid-crystalline (LC) molecule, has high molecular weight, negative charge and a semi-rigid structure. The aqueous solution of PBDT shows nematic liquid crystalline state above a critical PBDT concentration, CLC*, of 2 wt%-3wt%. Different from the flexible polyelectrolyte, PBDT shows a variety of self-assembling structures in aqueous solution with and without salt due to the semi-rigid nature and highly charged property. In addition, the hydrogels with ordered structure are developed by polymerizing a cationic monomer N-[3-(N,N-dimethylamino) propyl] acrylamide methyl chloride quarternary (DMAPAA-Q) in the presence of a small amount of PBDT below the CLC*. During the polymerization of cationic monomer, the polycations form a complex with semi-rigid PBDT through electrostatic interaction; these complexes self-assemble into ordered structures that are frozen in the hydrogel. Several different structures, including the anisotropic, dual network-like structure, and cylindrically symmetric structure, with various length scales from micrometer to millimeter, are observed. The hydrogels with ordered liquid crystalline assemblies and particular optical properties should promise applications in many fields, such as in bionics, tissue engineering, and mechano-optical sensors.

THERMOSENSITIVE POLYION COMPLEX MICELLES PREPARED BY SELF-ASSEMBLY OF TWO OPPOSITELY CHARGED DIBLOCK COPOLYMERS

Polyion complex （PIC） micelles were spontaneously formed in aqueous solutions through electrostatic interaction between two oppositely charged block copolymers, poly（N-isopropylacrylamide）-b-poly（L-glutamic acid） and poly（N-isopropylacrylamide）-b-poly（L-lysine）. Their controlled synthesis was achieved via the ring opening polymerization of N-carboxyanhydrides （NCA）, ε-benzyloxycarbonyl-L-lysine （Lys（Z）-NCA） or γ-benzyl-L-glutamate （BLG-NCA） with amino-terminated poly（N-isopropylacrylamide） macroinitiator and the subsequent deprotection reaction. The formation of PIC micelles was confirmed by dynamic light scattering and transmission electron microscopy. Turbidimetric characterization suggested that the formed PIC micelles had a concentration-dependent thermosensitivity and their phase transition behaviors could be easily adjusted either by the block length of coplymers or the concentration of micelles.

Preparation of PLL-PEG-PLL and its application to DNA encapsulation

PLL-PEG-PLL was synthesized by deprotection of the amino group of PLL(Z)-PEG-PLL(Z). The properties of the polyion complex (PIC) micelles comprising of PLL-PEG-PLL and DNA were investigated. The results showed that the core of PIC was formed by PLL and DNA through electrostatic interactions, and PEG was shell of PIC, so PIC micelles in aque- ous medium were homogenous with no precipitation even under the neutral condition, and PIC had the characteristic of stability, which were very important in gene therapy. At the same time, the results showed PLL-PEG-PLL could condense DNA, longer PLL blocks were generally more effective at condensation, and the nuclease resistance of DNA was increased remarkably. PIC was spherical with diameter of 10―35 nm, which could be easily taken up by cells. Transfection experiments in vitro showed that the DNA encapsulated could be expressed in the cell line SF9.

Potentiometric sensor for sensitive and selective detection of heparin

A polymeric membrane ion-selective electrode for determination of heparin is described in this paper.Protamine is incorporated into the organic membrane phase and functions as sensing element for selective recognition of heparin.The proposed membrane electrode exhibits high selectivity for heparin over lipophilic anions such as thiocyanide and salicylate.The potentiometric response to the concentration of heparin is Unear in the range of 0.01-0.4 U/mL and a lower detection limit of 0.005 U/mL can be achieved.