Preparation and application of PGMA-DVB microspheres via surface-modification with quaternary and phenylboronic acid moiety

Porous cross-linked poly (glycidyl methacrylate-divinylbenzene) (PGMA-DVB) particles (7.42 ± 0.24 μm in diameter) were prepared by an improved two-step seed swelling polymerization method. The PGMA-DVB particles were further modified with poly (allylamine hydrochloride) (PAH) and 4-(bromomethyl) phenylboronic acid (BPA), which were used as high performance liquid chromatography (HPLC) filler for nucleotides separation. The liquid chromatographic column packing materials successfully achieved complete separation of nucleotides mixture or deoxynucleotides mixture based on non-polar adsorption, hydrogen bonding interaction and electrostatic adsorption. Reckoning on the chemical structure of BPA, nucleotides and deoxynucleotides with same base group were also separated. The column packing materials were durable after over 100 time running or 7 days. It presents a kind of new notion for the separation of nucleotides by HPLC.

Surface coordination polymerization of ethylene by hydrozirconation-immobilized metallocene

Hydrozirconation on vinyl-terminated substrates (silicon wafer and nanosilica sphere) is employed as an efficient way for immobilization of zirconocene catalyst through Zr-C bonds, which is applied in surface coordination ethylene polymerization producing surface-tethered polyethylene (PE). The formation of Zr-C σ bond induced by hydrozirconation provides an initiator precursor for growing a layer of PE covalently linked onto substrates. The results from SEM, AFM, and TEM show that the surface polymerization is controlled by hydrozirconation. Surface pattern or core-shell structure with crystalline PE coating can be formed, when silicon wafer is selectively functionalized with vinyl-groups or vinyl-modified nanosilica is applied. It is believed that hydrozirconation for the synthesis of zirconocene initiator can be a versatile route to prepare polyolefin hybrid materials.

Fabrication of microspheres via solvent volatization induced aggregation of self-assembled nanomicellar structures and their use as a pH-dependent drug release system

A series of oleamide derivatives, (C(18)H(34)NO)(2)(CH(2))(n) [n = 2 (1a), 3 (1b), 4 (1c), or 6 (1d); C(18)H(34)NO = oleic amide fragment] and (C(18)H(34)NO)(CH(2))(6)NH(2) (2), have been synthesized and their self-assembly is investigated in ethanol/water media. Self-assembly of 1a and 1b in ethanol/water (1/0.1 v/v) solution (5 mg mL(-1)) yields microspheres (MSs) with the average diameter ∼10 μm via a gradual temperature reduction and solvent volatilization process. Under the same self-assembly conditions, microrods (average diameter ∼6 μm and several tens of micrometers in length), micronecklace-like, and shape-irregular microparticles are formed from the self-assembly of 1c, 1d, and 2, respectively. The kinetics of evolution for their self-assemblies by dynamic light scattering technique and in situ observation by optical microscopy reveals that the microstructures formation is from a well-behaved aggregation of nanoscale micelles induced by solvent volatilization. The FT-IR and temperature-dependent (1)H-NMR spectra demonstrate the hydrogen bonding force and π-π stacking, which drove the self-assembly of all oleamide derivatives in ethanol/water. Among the fabricated microstructures, the MSs from 1a exhibit the best dispersity, which thus have been used as a scaffold for the in vitro release of doxorubicin. The results demonstrate a pH-sensitive release process, enhanced release specifically at low pH 5.2.