Fabrication of multifunctional shell cross-linked micelles for targeting drug release

Thermosensitive amphiphilic poly(N-acroyloxysuccinimide)-b-poly(N-isopropylacrylamide)-b-poly(??-caprolactone) triblock copolymer was synthesized via the combination of reversible addition fragmentation chain transfer and ring-opening polymerization techniques. Shell cross-linked micelle (SCL) was further developed by the addition of cystamine as a di-functional cross-linker into the micellar solution. The persistence of regularly spherical shape against media change demonstrated locked micellar structure resulting from sufficient shell cross-linking. The lower critical solution temperature of the resulting SCL micelles was around 38?°C. The in vitro drug release study was carried out to illustrate the temperature-responsive drug release behaviors. To enhance the internalization to tumor cells, transferring (Tf) was further conjugated to the SCL micelles, and endocytosis experiments further confirmed the efficient uptake of Tf-SCL micelles by tumor cells, indicating that the Tf-SCL micelles would be a promising candidate for tumor-targeted drug delivery.     

Sponge-like nanostructured conducting polymers for electrically controlled drug release

An electrically controlled drug release (ECDR) system based on sponge-like nanostructured conducting polymer (CP) polypyrrole (PPy) film was developed. The nanostructured PPy film was composed of template-synthesized nanoporous PPy covered with a thin protective PPy layer. The proposed controlled release system can load drug molecules in the polymer backbones and inside the nanoholes respectively. Electrical stimulation can release drugs from both the polymer backbones and the nanoholes, which significantly improves the drug load and release efficiency. Furthermore, with one drug incorporated in the polymer backbone during electrochemical polymerization, the nanoholes inside the polymer can act as containers to store a different drug, and simultaneous electrically triggered release of different drugs can be realized with this system.     

Electrodeposited conductive polymers for controlled drug release: polypyrrole

Over the last 40 years, electrically conductive polymers have become well established as important electrode materials. Polyanilines, polythiophenes and polypyrroles have received particular attention due to their ease of synthesis, chemical stability, mechanical robustness and the ability to tailor their properties. Electrochemical synthesis of these materials as films have proved to be a robust and simple way to realise surface layers with controlled thickness, electrical conductivity and ion transport. In the last decade, the biomedical compatibility of electrodeposited polymers has become recognised; in particular, polypyrroles have been studied extensively and can provide an effective route to pharmaceutical drug release. The factors controlling the electrodeposition of this polymer from practical electrolytes are considered in this review including electrolyte composition and operating conditions such as the temperature and electrode potential. Voltammetry and current-time behaviour are seen to be effective techniques for film characterisation during and after their formation. The degree of take-up and the rate of drug release depend greatly on the structure, composition and oxidation state of the polymer film. Specialised aspects are considered, including galvanic cells with a Mg anode, use of catalytic nanomotors or implantable biofuel cells for a self-powered drug delivery system and nanoporous surfaces and nanostructures. Following a survey of polymer and drug types, progress in this field is summarised and aspects requiring further research are highlighted.     

A novel route for preparation of multifunctional polymeric nanocarriers for stimuli‐triggered drug release

Fluorescence‐incorporated, crosslinker‐free, pH‐ and thermoresponsive nanocarriers were prepared by the incorporation of drug molecules into the thermoresponsive nanocapsules, which composed of poly(N‐isopropylacrylamide) (PNIPAAm) with carboxylic acid end groups via temperature induced self‐assembling method. Well‐defined, pH‐responsive carboxylic acid group‐ended PNIPAAm homopolymer (HOOC? PNIPAAm? COOH) was synthesized by reversible addition fragmentation chain transfer polymerization with S,S′‐bis(α,α′‐dimethyl‐α″‐acetic acid)trithiocarbonate (CMP) as a chain transfer agent. Rhodamine 6G (R6G), the model drug, was used for three kinds of application: First, the nanostructure fixing; second, the fluorescence‐labeling; and last, the controlled release modeling. The transmission electron microscope images showed the solution type dosing led to the encapsulation of drug molecules into the nanocarriers, while the powder‐type drug‐loading process significantly contributed to the structure preservation of nanocarriers. The controlled release behaviors with various pH values and temperatures were evaluated. These multifunctional nanocarriers have potential to be applied for the biomedical therapy by stimuli‐responsive controlled release. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 561–571     

FeOOH-loaded mesoporous silica nanoparticles as a theranostic platform with pH-responsive MRI contrast enhancement and drug release

The development of stimuli-responsive theranostic platforms is of great demand for efficient cancer treatment because they can enhance diagnostic specificity and sensitivity.In this work,we report a p H-responsive theranostic nanoplatform based on Fe OOH clusters loaded mesoporous silica nanoparticles(Fe@MSNs).The as-synthesized Fe@MSNs possess activatable T_1magnetic resonance imaging(MRI)performance that can respond to the acidic microenvironment of solid tumor to turn on T_1singals by releasing paramagnetic Fe~(3+)ions.The Fe@MSNs are biocompatible without appreciable cytotoxicity.Moreover,the unique mesoporous structure endows the Fe@MSNs with significant advantages to effectively deliver chemotherapeutic drug for inhibiting the growth of solid tumor.We believe that this novel p H-responsive theranostic nanoplatform holds great promise in cancer treatment.     

Mechanochemical reactions of coordination polymers by grinding with KBr

Grinding of a one-dimensional (1-D) ladder coordination polymer (CP), [Zn(μ-CH(3)CO(2))(CF(3)CO(2))bpe] (1), and a hydrogen-bonded 1-D CP, [Cd(CH(3)CO(2))(2)bpe(H(2)O)] (2), with KBr resulted in the exchange of carboxylate by bromide ions and the formation of 1-D zigzag and 2-D CPs respectively.     

Mechanochemical preparation of drug carrier solid dispersions

The method of mechanical activation was used to obtain solid-state dispersions of some drugs in polyvinylpyrrolidone, polyethylene glycol and talc as carriers. Solid dispersions obtained by mechanical activation were found to have higher apparent solubilities and dissolution rates than mechanically activated drugs or their physical or eutectic mixtures with carriers used. It was shown by IR-spectroscopy and fluorescence measurements that mechanical treatment gave rise to an interaction between components which was apparently responsible for the solubilization effects observed.     

Ultrasound-triggered smart drug release from multifunctional core-shell capsules one-step fabricated by coaxial electrospray method

Multifunctional core-shell capsules that triggered release by ultrasound stimulus were one-step fabricated by the coaxial electrospray method. The TiO(2) shell suppressed the initial burst release of the paclitaxel. Fe(3)O(4) and graphene quantum dots inside the oil core functioned successfully for magnetic targeting and fluorescence imaging, respectively. Paclitaxel was trigger released when the dual layer of titania shell cracked under the ultrasound stimulation, and the releasing profile could be controlled by the length of applied ultrasound time.     

Carbazole main-chain polymers for multifunctional materials: Synthesis and characterization

A series of α,ω-bis(3-formylcarbazolyl)alkane monomers have been prepared starting from carbazole and α,ω-dibromoalkane in two steps. Main-chain polymers with carbazole substituted with one acceptor group as the nonlinear optical (NLO) chromophores and photoconductive moieties were synthesized by the Knoevenagel polycondensation of α,ω-bis(3-formylcarbazolyl)alkane and 1,6-bis(cyanoacetoxy)hexane using 4-(N,N-dimethyl)pyridine (DMAP) as a base. This Knoevenagel polycondensation involved two stages: polycondensation was first carried out in tetrahydrofuran solution, and then polycondensation was allowed to continue in the solid-state after removal of solvent. All of these main-chain polymers characterized by spectroscopic methods and elemental analyses are soluble in common low boiling organic solvents, such as chloroform. These polymers were found to be amorphous with glass transition temperatures in the range of 94–117°C by differential scanning calorimetry. This two-stage polycondensation gave polymers with weight-average molecular weight in the range of 25,000–72,000 g/mol by gel permeation chromatography. The study of the nonlinear optical and photorefractive properties of these polymers is in progress. © 1996 John Wiley & Sons, Inc.     

Novel multifunctional theranostic nanoagents based on Ho3+ for CT/MRI dual-modality imaging-guided photothermal therapy

Because of the intrinsic defects of traditional treatment of cancer,it is quite needed to construct novel theranostic nanoagents that can not only improve the accuracy of imaging diagnosis but also achieve highly efficient therapy of cancer.Herein,we fabricated polydopamine-functionalized ammonium holmium fluoride nanocomposites(AHF@PDA)for dual-modality bioimaging(magnetic resonance imaging(MRI)and computed tomography(CT))owing to the high X-ray attenuation feature and magnetic property of Ho³⁺.Moreover,PDA shell endows AHF@PDA with excellent photothermal conversion performances and robust biocompatibility,leading to good treatment effect in vitro and in vivo.All above positive results certify that AHF@PDA have good potential as theranostic agents for clinical application in the future.     

Mechanochemical activation of minerals on the cordierite synthesis

The cordierite is commonly prepared by reaction of talc, clay and gibbsite within the range of 1200-1350 °C. This study deals with the effect of the amorphization by grinding of that mixture and its influence on the cordierite formation.The mixture previously mentioned underwent six different treatments: mixing without grinding (A) (only mixing); non-amorphizing grinding (A_M) and amorphizing grinding in oscillating mill at four different times (H samples). The phases formed by thermal treatment were studied using differential thermal analysis (DTA)-thermogravimetric analysis (TG)-DTG, dilatometries and X-ray diffraction (XRD) techniques in certain combinations.The thermal analysis of the A and A_M series were compared and they do not show significant differences, whereas the H samples present remarkable alterations in the DTA peaks as well as in the weight losses (TG). Thus, a great number of DTA peaks tend to decrease the temperature of the maximum and to lower the intensity as the amorphization time increases.Calcination tests performed within the range 900-1200 °C show important differences in the diffractograms obtained from the intermediate products. While at 1350 °C the A and H samples reach the same final phases, within the range 1200-1360 °C they present important differences in the DTA indicating that the sequence and direction of reaction are different. The same behavior can be observed by dilatometric analysis.     

Mechanochemical activation in manufacture of defluorinated forage phosphate

The effect of preliminary mechanochemical activation of phosphate rock on the temperature of hydrothermal calcination and degree of defluorination in manufacture of defluorinated forage phosphates conforming to GOST (State Standard) 23 999–80 was studied. A mechanism of mechanochemical activation of phosphate raw materials, associated with changes in thermodynamic properties of the activated system, was suggested.     

多功能聚合物合成有机化学之进展

我们探索了利用钯催化反应合成新型多功能聚合物, 实验结果显示这类反应能与甚多官能团相容, 从而为聚合物化学家提供若干实用之合成方法。