Chlorambucil is a classic nitrogen mustard drug that has been used in the treatment of cancers. It may induce neutropenia, thrombocytopenia and other side effects because of its short lifetime and off-target effect. In this report, chlorambucil-tetrapeptide (AAAK, A₃K) conjugate vesicles were developed to improve the stability and bioactivity of chlorambucil. First of all, chlorambucil-A₃K conjugate was synthesized by solid phase synthesis strategy. Secondly, the chlorambucil-A₃K conjugate was assembled and characterized by critical aggregation concentration, circular dichroism, dynamic light scattering and transmission electron microscopy. The results indicated that the chlorambucil-A₃K conjugate can be assembled to form spherical vesicles with an average diameter of 390.5 nm, and high drug loading about 47.1% is reached. Surprisingly, the preliminary biological evaluation of the chlorambucil-A₃K conjugate vesicles revealed the best in vitro anticancer activity against HeLa, HepG-2 and MCF-7 cell lines compared with chlorambucil and chlorambucil-A₃K conjugate free drugs. Furthermore, conjugate vesicles showed excellent in vivo antitumoral activity. It can be partly attributed to their vesicular structure which isolates chlorambucil active moiety from aqueous solution to retard degradation before killing cancer cells. Therefore, chlorambucil-peptide (A₃K) conjugate vesicles may be an alternative delivery system of chlorambucil.

Enzymatic crosslinking was developed to prepare in situ forming poly(γ-glutamic acid) (γ-PGA) based hydrogel in this study. First, the precursor of poly(γ-glutamic acid)–tyramine (γ-PGA–Ty) was synthesized through the reaction of carboxyl groups from a γ-PGA backbone with tyramine. The structure of the grafted precursor was confirmed by ¹H-NMR and Fourier transform infrared spectroscopy. After that, the crosslinking of the phenol-containing γ-PGA–Ty precursor was triggered by horseradish peroxidase in the presence of H₂O₂; this resulted in the formation of the γ-PGA–Ty hydrogels. The equilibrium water content, morphology, enzymatic degradation rate, and mechanical properties of the hydrogels were characterized in detail. The data revealed that the well-interconnected hydrogels had tunable water contents, mechanical properties, and degradability through adjustments of the composition. Furthermore, cell experiments proved the biocompatibility of the hydrogels by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. These characteristics provide an opportunity for the in situ formation of injectable biohydrogels as potential candidates in cell encapsulation and drug delivery. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42301.

We report a novel dual drug-tailed phospholipid which can form liposomes as a combination of prodrug and drug carrier. An amphiphilic dual chlorambucil-tailed phospholipid (DCTP) was synthesized by a straightforward esterification. With two chlorambucil molecules as hydrophobic tails and one glycerophosphatidylcholine molecule as a hydrophilic head, the DCTP, a phospholipid prodrug, undergoes assembly to form a liposome without any additives by the thin lipid film technique. The DCTP liposomes, as an effective carrier of chlorambucil, exhibited a very high loading capacity and excellent stability. The liposomes had higher cytotoxic effects to cancer cell lines than free DCTP and chlorambucil. The in vivo antitumor activity assessment indicated that the DCTP liposomes could inhibit the tumor growth effectively. This novel strategy of dual drug-tailed phospholipid liposomes may be also applicable to other hydrophobic anticancer drugs which have great potential in cancer therapy.

Gelatin is a popular substrate for cell culture applications due to its biocompatibility and biodegradability. However, the mechanical property of gelatin is not satisfactory in certain tissue engineering areas where tunable and higher mechanical strengths are required. To achieve this purpose without exposure of materials to cytotoxic chemicals or procedures, a new biohydrogel of gelatin and gellan gum with an interpenetrating network (IPN) structure was prepared using a combination of enzymatic and ionic crosslinking approaches. The gelation procedure and thermal stability of the IPN structure were demonstrated in detail by a rheological study. The resulting IPN biohydrogel exhibited significantly increased and tunable mechanical strength, decreased swelling ratios and lower degradation rate compared with pure gelatin gel. The composite biohydrogels supported the attachment and proliferation of L929 fibroblasts as shown in vitro. These results indicate that this mechanically robust biohydrogel has the promising potential for serving as a cell support in the field of tissue engineering. © 2013 Society of Chemical Industry

A novel amphiphilic hydrogel based on poly(2-methyl-2-oxazoline)-b-poly(dimethyl siloxane) (PMeOx–PDMS) block copolymer was developed. First of all, PMeOx–PDMS macromonomer was synthesized by coupling mono-hydroxylated PMeOx with PDMS followed by end-capping with methacrylate group. The structures of each step were characterized by NMR and titration. After that, silicone hydrogels were prepared by UV-initiated copolymerization of PMeOx–PDMS macromonomer with monomers such as 2-hydroxyethyl methacrylate in the presence of a crosslinker. Measurements of the hydrogels' water contact angle, equilibrium water content, and tensile properties showed that the hydrogels possessed better hydrophilic surface, higher water content, and better ion permeability with the increase of the content of the macromonomer PMeOx–PDMS. Meanwhile, the tensile strength and Young's modulus of the hydrogels decreased slightly. Protein adsorption tests showed that the hydrogels had strong antifouling ability after the incorporation of PMeOx. This newly described hydrogel demonstrated attractive properties to serve as ophthalmic biomaterial. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39867.

Hydrogels of a natural origin have attracted considerable attention in the field of tissue engineering due to their resemblance to ECM, defined degradability and compatibility with biological systems. In this study, we introduced carrageenan into a gelatin network, creating IPN hydrogels through biological methods of enzymatic and ionic crosslinking. Their gelation processes were monitored and confirmed by rheology analysis. The combination of biochemical and physical crosslinking processes enables the formation of biohydrogels with tunable mechanical properties, swelling ratios and degradation behaviors while maintaining the biocompatibilities of natural materials. The mechanical strength increased with an increase in carrageenan content while swelling ratio and degradability decreased correspondingly. In addition, the IPN hydrogels were shown to support adhesion and proliferation of L929 cell line. All the results highlighted the use of biological crosslinked gelatin-carrageenan IPN hydrogels in the context of tissue engineering. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 10.1002/app.40975.

Nanofiber filtration is drawing an ever-increasing attention nowadays because of its high filtration efficiency as well as low basic weight. The objective of this study is to investigate the effect of structural characteristics on filtration performance with a single nanofiber mat between two pieces of nonwoven membranes. The filtration performance of nanofiber mats was evaluated by quality factor, the ratio of aerosol filtration efficiency to pressure drop. It was found that the quality factor dropped rapidly when the average fiber diameter (d_f) increased from 358 to 425 nm and decreased slowly from d_f = 425 nm to d_f = 1250 nm. This proved that gas-slip effect occurred on nanofibers with smaller diameters. Similarly, the quality factor of unimodal nanofiber mat declined as the packing density increased. Meanwhile, these data were compared with corresponding prediction of ideal mats predominantly from theoretical equations. Nanofiber mats with bimodal fiber size distributions were tested at the same condition. When compared with the unimodal nanofiber mats having the same weight-averaged fiber diameter and similar packing density, the bimodal nanofiber mats exhibited higher quality factors. Hence, the bimodal method is an effective method for the improvement of filtration performance. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

In the present work, sequential interpenetrating polymer networks (IPNs) based on silicone and poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) were developed with improved protein resistance. The structure and morphology of the IPNs were characterized by Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The results showed that the IPNs exhibited heterogeneous morphology. The bulk properties such as water content, ion permeability, and mechanical strength of the IPNs were determined by gravimetric method, ionoflux measurement technique, and tensile tester, respectively. The surface characteristics of the IPNs were investigated by X-ray photoelectron spectroscopy (XPS) and contact angle measurements. XPS analysis suggested that PMPC was present on the surface as well as in the bulk material. The IPNs possessed more hydrophilic surface than pristine silicone revealed by contact angle measurements. Bovine serum albumin (BSA) was used as a model protein to evaluate protein resistance by a bicinchoninic acid assay method. The result revealed that the protein adsorption on the IPNs was significantly reduced compared to pristine silicone. These results suggest that the IPNs based on silicone and PMPC may be developed as novel ophthalmic biomaterials. Copyright © 2010 John Wiley & Sons, Ltd.

In this work, sequential interpenetrating polymer networks (IPNs) based on poly(2-hydroxyethyl methacrylate) (PHEMA) and poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC) were prepared with improved protein resistance. The bulk properties of the IPN hydrogels such as water content, ion permeability and mechanical strength were determined by the gravimetric method, ionoflux measurement technique and tensile tester respectively. The surface characteristics of the IPNs were investigated by X-ray photoelectron spectroscopy (XPS) and contact angle measurements. XPS analysis suggested that PMPC was present on the surface and in the bulk material. The IPN hydrogels possessed more hydrophilic surface than PHEMA revealed by contact angle measurements. Bovine serum albumin was used as a model protein to evaluate protein resistance by bicinchoninic acid assay method. The result revealed that the protein adsorption on the IPNs showed dramatically reduction compared to PHEMA. These results suggest that the IPNs based on PHEMA and PMPC may be further developed as ophthalmic biomaterials. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

In the current work, interpenetrating polymer network (IPN) silicone hydrogels are prepared by UV-initiated polymerization of acrylate monomers including siloxane macromer, methacryloxypropyl tris (trimethylsiloxy) silane (TRIS) and N,N-dimethylacrylamide (DMA)/N-vinyl-2-pyrrolidone (NVP) in the presence of free radical and cationic photoinitiators. The polymerization mechanism is investigated preliminarily by the formation of gel network. The morphology of the hydrogels is characterized by fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and transmission electron microscope (TEM). The results show that the IPN hydrogels exhibit a heterogeneous morphology. The surface wettability is examined by the contact angle goniometer. The result reveals that the IPN silicone hydrogels possess hydrophilic surfaces with the lowest water contact angle of 59°. Furthermore, the oxygen permeability of the hydrogels is measured by an oxygen transmission tester. The results indicate that the IPN silicone hydrogels have excellent oxygen permeability with the highest Dk of 226 barrer. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

This work reports the preparation of 2-hydroxyethyl methacrylate (HEMA)/N-vinyl-2-pyrrolidone (NVP) interpenetrating polymer network (IPN) hydrogels by UV-initiated polymerization in the presence of free radical photoinitiator Darocur 1173 and cationic photoinitiator 4,4′-dimethyl diphenyl iodonium hexafluorophosphate. The polymerization mechanism was investigated by the formation of gel network. The structure and morphology of the HEMA/NVP IPN hydrogels were characterized by fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). The results showed that the IPN gels exhibited homogeneous morphology. The dehydration rates of HEMA/NVP IPN hydrogels were examined by the gravimetric method. The results revealed that the hydrogels had a significant improvement of antidehydration ability in comparison with poly(2-hydroxyethyl methacrylate)(PHEMA) hydrogel embedded physically with poly(N-vinyl-2-pyrrolidone)(PVP). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

BACKGROUND: Electrospinning of natural polymers offers a promising approach to generate nanofibers with a similar fibrillar structure to that of native extracellular matrix. In the present work, zein/silk fibroin (SF) blends were electrospun with formic acid as solvent to fabricate bicomponent nanofibrous scaffolds for biomedical applications.

RESULTS: The zein/SF electrospun nanofibers had a smaller diameter and narrower diameter distribution than pure zein nanofibers, and the average diameter gradually decreased from 265 to 230 nm with increasing SF content in the blend. The predominant presence of α-helix zein structure and random coil form of silk I in blend fibrous membranes was confirmed from Fourier transform infrared spectral and wide-angle X-ray diffraction data, while conversion to the β-sheet structure of SF was also detected. The tensile strength of the zein/SF fibrous membranes was improved as the content of SF in the blend fibers increased. A preliminary study of in vitro degradation and cytotoxicity evaluated by MTT assay indicated that biodegradable zein/SF fibrous membranes did not induce cytotoxic effects in an L929 mouse fibroblast system.

CONCLUSION: Biodegradable zein/SF fibrous membranes with good mechanical properties and cytocompatibility combine the beneficial characteristics of the individual components and may be useful for biomedical applications. Copyright © 2009 Society of Chemical Industry

Zein and zein/poly-L-lactide (PLLA) nanofiber yarns were prepared by conjugate electrospinning using coupled spinnerets applied with two high electrical voltages of opposite polarities in this article. Structure and morphology of zein yarns were investigated by SEM and X-ray diffraction. The results showed that zein yarn consisted of large quantity of fibers with diameters ranging from several hundreds nanometers to a few microns, and zein concentration played a significant role on the diameter of nanofibers in yarns. To improve mechanical property of nanofiber yarns, PLLA was then incorporated with zein. Zein/PLLA composite nanofiber yarns conjugate electrospun from solution with concentration of 7.5% (zein, w/v)/7.5% (PLLA, w/v) exhibited tensile strength of 0.305 ± 0.014 cN/dtex. The composite yarns showed better nanofiber alignment along the longitudinal axis. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

The continuous nanofiber yarns of poly(L-lactide) (PLLA)/nano-β-tricalcium phosphate (n-TCP) composite are prepared from oppositely charged electrospun nanofibers by conjugate electrospinning with coupled spinnerets. The morphology and mechanical properties of PLLA/n-TCP nanofiber yarns are characterized by scanning electron microscope, transmission electron microscope, and electronic fiber strength tester. The results show that PLLA/n-TCP nanofibers are aligned well along the longitudinal axis of the yarn, and the concentration of PLLA plays a significant role on the diameter of the nanofibers. The thicker yarn of PLLA/n-TCP composite with the weight ratio of 10/1 has been produced by multiple conjugate electrospinning using three pairs of spinnerets, and the yarn has tensile strength of 0.31cN/dtex. A preliminary study of cell biocompatibility suggests that PLLA/n-TCP nanofiber yarns may be useable scaffold materials. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008