Enhanced anti-tumor activity of a drug through pH-triggered release and dual targeting by calcium phosphate-covered mesoporous silica vehicles.

Rapid release and clearance of antitumor drugs in vivo are the main factors used to evade the effectiveness of chemotherapeutics. Targeted delivery and controlled release of drugs are the most pressing dilemmas in cancer therapy. Herein we report the design and fabrication of multifunctional mesoporous silica nanoparticles coated with poly(N-isopropylacrylamide)-co-acrylic acid and calcium phosphate (MSCNs) with pH-triggered chemotherapeutic release and dual-targeting functions. By decorating the nanoparticle surface with a transferrin (Tf)/RGD ligand, these nanoparticles are capable of not only recognizing the intrinsic pH difference between tumor and normal tissues, but also targeting the lesion location. It was shown that Tf/RGD-MSCNs delivered the anti-tumor drug doxorubicin more efficiently into lysosomes and the resulting DOX-loaded nanoparticles (DOX-Tf/RGD-MSCNs) showed a stronger inhibitory effect towards tumor cell growth than free DOX and DOX delivered by unmodified MSNs. Moreover, the nanoparticles are more biocompatible than uncoated mesoporous silica nanoparticles. All these results indicate that Tf/RGD-MSCNs have great potential as a novel drug carrier in therapeutic applications against cancers.

Growth factor loading on aliphatic polyester scaffolds.

Cells, scaffolds and growth factors are three elements of tissue engineering. The success of tissue engineering methods relies on precise and dynamic interactions between cells, scaffolds and growth factors. Aliphatic polyester scaffolds are promising tissue engineering scaffolds that possess good mechanical properties, low immunogenicity, non-toxicity, and adjustable degradation rates. How growth factors can be loaded onto/into aliphatic polyester scaffolds and be constantly released with the required bioactivity to regulate cell growth and promote defect tissue repair and regeneration has become the main concern of tissue engineering researchers. In this review, the existing main methods of loading growth factors on aliphatic polyester scaffolds, the release behavior of loaded growth factors and their positive effects on cell, tissue repair and regeneration are introduced. Advantages and shortcomings of each method also are mentioned. It is still a great challenge to control the release of loaded growth factors at a certain time and at a concentration simulating the biological environment of native tissue.

Carbon-dot-supported atomically dispersed gold as a mitochondrial oxidative stress amplifier for cancer treatment.

Mitochondrial redox homeostasis, the balance between reactive oxygen species and antioxidants such as glutathione, plays critical roles in many biological processes, including biosynthesis and apoptosis, and thus is a potential target for cancer treatment. Here, we report a mitochondrial oxidative stress amplifier, MitoCAT-g, which consists of carbon-dot-supported atomically dispersed gold (CAT-g) with further surface modifications of triphenylphosphine and cinnamaldehyde. We find that the MitoCAT-g particles specifically target mitochondria and deplete mitochondrial glutathione with atomic economy, thus amplifying the reactive oxygen species damage caused by cinnamaldehyde and finally leading to apoptosis in cancer cells. We show that imaging-guided interventional injection of these particles potently inhibits tumour growth in subcutaneous and orthotopic patient-derived xenograft hepatocellular carcinoma models without adverse effects. Our study demonstrates that MitoCAT-g amplifies the oxidative stress in mitochondria and suppresses tumour growth in vivo, representing a promising agent for anticancer applications.

Fabrication and effect on regulating vSMC phenotype of a biomimetic tunica media scaffold.

An ideal vascular tissue engineering scaffold should imitate physical and biochemical cues in native vessels for guiding cell growth, differentiation and tissue formation. The tunica media provides a key structure and function support for native vessels. In this study, a film-like MNP-TGF/bFGF-PLGA scaffold that simulated physical and biochemical cues of tunica media in native vessels was fabricated by soft lithography combined with solution casting and phase separation technique. The scaffold had dual surface topographies of parallel arranged microgrooves and nanofiber structures, and interconnected pores to be able to deliver nutrient and eliminate metabolized products. The TGF-ß1 and bFGF immobilized on the scaffold by silica nanoparticle binding and plasma treatment technique could maintain continuous release for 10 and 7 days, respectively. The synergy effect of the dual surface topography and released growth factors endowed the MNP-TGF/bFGF-PLGA scaffold with good capacity on regulating vascular smooth muscle cell (vSMC) phenotype. Importantly, the scaffold possessed good mechanical properties and could easily be rolled into a multilayer cylindrical tube as a promising biomimic vascular tissue engineering scaffold.

Hybrid Mesoporous Silica-Based Drug Carrier Nanostructures with Improved Degradability by Hydroxyapatite.

Potential bioaccumulation is one of the biggest limitations for silica nanodrug delivery systems in cancer therapy. In this study, a mesoporous silica nanoparticles/hydroxyapatite (MSNs/HAP) hybrid drug carrier, which enhanced the biodegradability of silica, was developed by a one-step method. The morphology and structure of the nanoparticles were characterized by TEM, DLS, FT-IR, XRD, N2 adsorption-desorption isotherms, and XPS, and the drug loading and release behaviors were tested. TEM and ICP-OES results indicate that the degradability of the nanoparticles has been significantly improved by Ca(2+) escape from the skeleton in an acid environment. The MSNs/HAP sample exhibits a higher drug loading content of about 5 times that of MSNs. The biological experiment results show that the MSNs/HAP not only exhibits good biocompatibility and antitumor effect but also greatly reduces the side effects of free DOX. The as-synthesized hybrid nanoparticles may act as a promising drug delivery system due to their good biocompatibility, high drug loading efficiency, pH sensitivity, and excellent biodegradability.

A biomimetic 3D microtubule-orientated poly(lactide-co-glycolide) scaffold with interconnected pores for tissue engineering.

An ideal tissue engineering scaffold should imitate physical and biochemical cues of natural extracellular matrix and have interconnected porous structures with high porosity to provide adequate space for cell seeding, growth and proliferation, as well as nutrient delivery and metabolized product elimination. In this study, we examined the feasibility of fabricating microtubule-orientated poly(lactide-co-glycolide) (PLGA) scaffolds with interconnected pores (denoted as MOIP-PLGA) by an improved thermal-induced phase separation technique. We successfully constructed MOIP-PLGA using 1,4-dioxane as the first solvent and benzene or water with lower freezing point as the second solvent. Especially, when water was used, the MOIP-PLGA had higher porosity and it could guide rabbit aortic smooth muscle cells (SMCs) to better grow along the microtubule direction of the scaffold. Comparing with microtubule-orientated scaffold without interconnected pores (denoted as MONIP-PLGA), the proliferation and viability of SMCs cultured on MOIP-PLGA were higher. Moreover, basic fibroblast growth factor could be effectively bound on MOIP-PLGA by a plasma treatment technique and the growth factor could be slowly released in vitro, maintaining bioactivity.

Multifunctional hybrid silica nanoparticles for controlled doxorubicin loading and release with thermal and pH dually response.

Controlled drug loading and release into tumor cells to increase the intracellular drug concentration is a major challenge for cancer therapy due to resistance and inefficient cellular uptake. Here a temperature and pH dually responsive PNiPAM/AA@SiO2 core-shell particles with internal controlled release were designed and fabricated for efficient cancer treatment, which could recognize the intrinsic pH differences between cancers and normal tissues. Upon lowering the temperature, doxorubicin was loaded into the PNiPAM/AA@SiO2 nanoparticles, whereas by increasing the acidity, previously loaded doxorubicin was quickly released. Comparing with common mesoporous silica particles (MSNs), this core-shell particle has more uniform size and better dispersity. In addition, dried PNiPAM/AA@SiO2 nanoparticles could be easily redispersed in distilled water. The in vitro cell culture experiments showed that not only PNiPAM/AA@SiO2 particles were more biocompatible and lower cytotoxic than MSN, but also DOX@PNiPAM/AA@SiO2 had higher drug releasing efficiency in the lysosomes and stronger inhibitory effect on tumor cell growth than DOX@MSN. All these features indicated that PNiPAM/AA@SiO2 particles have great potential in therapy applications.

Enhanced siRNA delivery and silencing gold-chitosan nanosystem with surface charge-reversal polymer assembly and good biocompatibility.

A simple nanocarrier coated with chitosan and the pH-responsive charge-reversible polymer, PAH-Cit, was constructed using layer-by-layer assembly to deliver siRNA. Gold nanoparticles (AuNPs) were di-rectly reduced and stabilized by chitosan (CS), forming a positively charged AuNP-CS core. Charge-reversible PAH-Cit and polyethylenimine (PEI) were sequentially deposited onto the surface of AuNP-CS through electrostatic interaction, forming a PEI/PAH-Cit/AuNP-CS shell/core structure. After loading siRNA, the cytotoxicity of siRNA/PEI/PAH-Cit/AuNP-CS against HeLa and MCF-7R cells was negligible. This vehicle completely protected siRNA against enzymatic degradation at vector/RNA mass ratios of 2.5:1 and above. An in vitro release profile demonstrated an efficient siRNA release (79%) from siRNA/PEI/PAH-Cit/AuNP-CS at pH 5.5, suggesting a pH-induced charge-reversing action of PAH-Cit. This mechanism also worked in vivo and facilitated the escape of siRNA from endosomes. Using this carrier, the uptake of cy5-siRNA by HeLa cells was significantly increased compared to PEI, an efficient polycationic transfection reagent. In drug-resistant MCF-7 cells, specific gene silencing effectively reduced expression of MDR1, the gene encoding the drug exporter P-gp, and consequently promoted the uptake of doxorubicin. This simple charge-reversal polymer assembly nanosystem has three essential benefits (protection, efficient uptake, and facilitated escape) and provides a safe strategy with good biocompatibility for enhanced siRNA delivery and silencing.

Cell affinity for bFGF immobilized heparin-containing poly(lactide-co-glycolide) scaffolds.

In order to effectively and uniformly immobilize basic fibroblast growth factor (bFGF) to thick PLGA scaffold, the heparin-conjugated PLGA (H-PLGA) was synthesized at the first by reaction between heparin and a low molecular weight PLGA. Then heparin-containing PLGA (H-PLGA/PLGA) scaffold was fabricated by blending the H-PLGA with a high molecular weight PLGA. Finally, bFGF was immobilized on the H-PLGA/PLGA scaffold mainly by static electricity action between them. The effect of H-PLGA content on bFGF binding efficiency of the H-PLGA/PLGA scaffolds was investigated. It was found that bFGF binding efficiency increased with increasing H-PLGA content. The bound bFGF can release in vitro slowly from the H-PLGA/PLGA scaffolds and last over two weeks. The released bFGF has still preserved its bioactivity. The attachment and growth of mouse 3T3 fibroblasts on the H-PLGA/PLGA scaffolds were better than that on the PLGA scaffold, however bFGF immobilized H-PLGA/PLGA scaffolds showed much better cell affinity. Therefore, the method to use the H-PLGA/PLGA scaffold for immobilizing bFGF is not only effective for slow delivering bFGF with bioactivity, but also can be used for fabricating thick scaffold where bFGF could be combined and uniformly distributed.

An injectable scaffold: rhBMP-2-loaded poly(lactide-co-glycolide)/hydroxyapatite composite microspheres.

Poly(lactide-co-glycolide)/hydroxyapatite(50/50) (PLGA/HA(50/50)) composite microspheres were fabricated and treated with a mixture of 0.25M NaOH aqueous solution and ethanol (v/v=1/1) at 37 degrees C. The properties of untreated and treated PLGA/HA(50/50) composite microspheres were determined and compared. The results showed that the surface roughness, HA content and hydrophilicity of the treated PLGA/HA(50/50) composite microspheres increased with treatment time. However, the treatment time should be kept within 2h in order to maintain the shape of the PLGA/HA(50/50) microspheres. At the same time, a degradation study showed that both the untreated and treated microspheres degraded gradually with time, with the treated microspheres degrading faster in the first 4 weeks. The rhBMP-2-loaded PLGA/HA(50/50) composite microspheres were prepared by solution dipping treated PLGA/HA(50/50) composite microspheres. Mouse OCT-1 osteoblast-like cells were cultured on the untreated, treated and rhBMP-2-loaded PLGA/HA(50/50) composite microspheres and the cell affinity of the various microspheres was assessed and compared. It was found that the surface-treated PLGA/HA(50/50) composite microspheres clearly promoted osteoblast attachment, proliferation and alkaline phosphatase activity. It was considered that the hydrophilicity, osteoconductivity and surface roughness were increased by the increase in the HA component, which facilitated cell growth. Moreover, the rhBMP-2 loaded on the treated PLGA/HA(50/50) composite microspheres could be slowly released and further enhanced osteoblast differentiation. The good cell affinity and enhanced osteogenic potential of the rhBMP-2-loaded PLGA/HA composite microspheres indicate that they could be used as an injectable scaffold.

The bioactivity of rhBMP-2 immobilized poly(lactide-co-glycolide) scaffolds.

In this study, immobilization of rhBMP-2 on polylactone-type polymer scaffolds via plasma treatment was investigated. To introduce proper functional groups on the surface of poly(lactide-co-glycolide) (PLGA) matrix, PLGA films were treated under different atmospheres, such as oxygen, ammonia and carbon dioxide, respectively, and then incubated in rhBMP-2 solution of de-ionized water. The effect of various plasma-treated PLGA films on binding rhBMP-2 was investigated and compared. It was found that PLGA binding ability to rhBMP-2 was enhanced by carbon dioxide and oxygen plasma treatment, and the binding ability of the oxygen plasma-treated PLGA (OT-PLGA) to rhBMP-2 was the strongest after oxygen plasma treating for 10 min under a power of 50 W. The changes of surface chemistry and surface topography of PLGA matrix induced by oxygen plasma treatment played main roles in improving the PLGA binding ability to rhBMP-2. The stability of rhBMP-2 bound on OT-PLGA film was determined under a dynamic condition by a Parallel Plate Flow Chamber. The result showed that the rhBMP-2 had been immobilized on the OT-PLGA film. Mouse OCT-1 osteoblast-like cell as a model cell was cultured on the rhBMP-2 bound OT-PLGA (OT-PLGA/BMP) in vitro, which showed that the bound rhBMP-2 via oxygen plasma treatment was bioactive. Depending on hydrophilicity and rich polar O-containing groups of the OT-PLGA scaffold, different amount of rhBMP-2 could be evenly immobilized on the surface of the OT-PLGA scaffold. The immobilized rhBMP-2 had stimulated differentiation of OCT-1 cell and accelerated process of mineralization of OCT-1 cell in the scaffold. It revealed the rhBMP-2 immobilized PLGA scaffold had good cell affinity.

Crystallinity control of apatite through Ca-EDTA complexes and porous composites with PLGA.

Apatite compounds with different levels of crystallinity were prepared using Ca-EDTA complexes. Ca-deficient hydroxyapatite (CDHA) with low crystallinity was synthesized by ultrasonic stirring of a mixture of Ca-EDTA complex, phosphoric acid, and ammonium hydroxide in hydrogen peroxide aqueous solution. Mixtures of carbonate hydroxyapatite (HA) and CDHA with higher crystallinity were also prepared from a solution involving the same complex. The porous composites with lower or higher crystallinity apatite with a copolymer of poly(L-lactide-co-glycilide)(70/30) (PLGA(70/30)) were fabricated by a solution-casting/particles leaching method. The apatites and porous composites were characterized, and it was found that the degradation of composites of apatite with a low level of crystallinity was fastest in phosphate-bufferd saline (PBS) solution compared with other apatite composites with higher levels of crystallinity; however, the rate was smaller than that of PLGA alone. Plasma treatment influenced the degradation of composites in PBS and apatite precipitation in simulated body fluid (SBF). Hydroxyapatite deposition on the PLGA composite with the low crystallinity occurred six times faster than that on PLGA alone after immersion in SBF. The incorporation of apatite into the PLGA matrix did not cause any adverse effects on cell attachment in an assay employing human gingival fibroblasts. This study suggested that the current apatite and PLGA porous composite will be a promising scaffold material for tissue engineering.

Preparation and cell affinity of microtubular orientation-structured PLGA(70/30) blood vessel scaffold.

In this study, a kind of microtubular orientation-structured blood vessel mimicking natural structure was fabricated with poly(lactide-co-glycolide)(70/30) (PLGA(70/30)) solutions in 1,4-dioxane by an improved thermal-induced phase separation (TIPS) technique. The effect of main factors of the TIPS technique, such as environmental temperature, temperature gradient and concentration of the polymer solution on the structure and morphology of formed vessel scaffold was investigated. It was observed that the outer-wall of the scaffold became thick obviously and the microtubules neighboring the outer-wall became disordered with environmental temperature increasing. The diameter of microtubules of vessel scaffolds reduced with temperature gradient increasing or concentration of the polymer solution increasing. By controlling parameters of the TIPS, the scaffolds with various morphologies could be manufactured, which had different diameters of microtubules. On the other hand, inner-diameter and outer-diameter of the vessel scaffolds could be controlled by adjusting size of the polyethylene mould. Cell affinity of the scaffolds was tested in vitro by using A10 cell as model cells. Results showed that the cells grew well in the vessel scaffolds which were modified by ammonia plasma treatment and then anchored with collagen. The cells could array along the direction of the microtubules.

The immobilization of basic fibroblast growth factor on plasma-treated poly(lactide-co-glycolide).

In this study, possibility of the method of immobilization of basic fibroblast growth factor (bFGF) on polylactone-type polymer scaffolds via plasma treatment was investigated. To introduce acid carboxylic functional groups on the surface of the polymer matrix, poly(lactide-co-glycolide) (PLGA) film was treated with carbon dioxide (CO2) plasma and then incubated in a phosphate buffer saline (PBS, pH 7.4) solution of bFGF. The bFGF binding efficiency to the CO2 plasma-treated PLGA (PT-PLGA) films under different treating parameters was investigated and compared. It was found bFGF binding efficiency to PLGA was enhanced by CO2 plasma treatment. The binding efficiency of bFGF to PLGA was variational with CO2 plasma treating time and it reached a maximum after a treating time of 20min under the power of 20W. The changes of surface chemistry and surface topography induced by CO2 plasma treatment played main roles in improving binding efficiency. Bound bFGF was released continuously from the films for up to 7 days in vitro. The stability of bFGF immobilized on PLGA film via CO2 plasma treatment was tested further under dynamic conditions by a Parallel Plate Flow Chamber. Mouse 3T3 fibroblasts were cultured on the bFGF bound PLGA with a prior plasma treatment (20W, 20min) (PT-PLGA/bFGF) film, which showed that bFGF released from PT-PLGA/bFGF film was bioactive. Adhesion and growth of cells on PLGA scaffolds were greatly improved by immobilization of bFGF on them. Therefore, the method of CO2 plasma treatment combining bFGF anchorage not only was usable in delivering bFGF, but also could be applied extensively for surface modification of scaffolds in tissue engineering.

Combining oxygen plasma treatment with anchorage of cationized gelatin for enhancing cell affinity of poly(lactide-co-glycolide).

Surface characteristics greatly influence attachment and growth of cells on biomaterials. Although polylactone-type biodegradable polymers have been widely used as scaffold materials for tissue engineering, lack of cell recognition sites, poor hydrophilicity and low surface energy lead to a bad cell affinity of the polymers, which limit the usage of polymers as scaffolds in tissue engineering. In the present study, surface of poly (L-lactide-co-glycolide) (PLGA) was modified by a method of combining oxygen plasma treatment with anchorage of cationized gelatin. Modification effect of the method was compared with other methods of oxygen plasma treatment, cationized gelatin or gelatin coating and combining oxygen plasma treatment with anchorage of gelatin. The change of surface property was compared by contact angles, surface energy, X-ray photoelectron spectra (XPS), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM) measurement. The optimum oxygen pretreatment time determined by surface energy was 10 min when the power was 50 W and the oxygen pressure was 20 Pa. Analysis of the stability of gelatin and cationized gelatin anchored on PLGA by XPS, ATR-FTIR, contact angles and surface energy measurement indicated the cationized gelatin was more stable than gelatin. The result using mouse NIH 3T3 fibroblasts as model cells to evaluate cell affinity in vitro showed the cationized gelatin-anchored PLGA (OCG-PLGA) was more favorable for cell attachment and growth than oxygen plasma treated PLGA (O-PLGA) and gelatin-anchored PLGA (OG-PLGA). Moreover cell affinity of OCG-PLGA could match that of collagen-anchored PLGA (AC-PLGA). So the surface modification method combining oxygen plasma treatment with anchorage of cationized gelatin provides a universally effective way to enhance cell affinity of polylactone-type biodegradable polymers.

A new route for preparing coordination polymers from hydrothermal reactions involving in situ ligand synthesis.

The coordination chemistry of inorganic cobalt salt and the organic ligands H(4)bbh (=benzene-1,2,4,5-bihydrazide) and H(3)bcbh (=benzene-4-carboxylate-1,2-bihydrazide) generated through the in situ hydrothermal acylate reaction of H(4)bta (=benzene-1,2,4,5-tetracarboxylic acid) and H(3)btc (=benzene-1,2,4-tricarboxylic acid) with hydrazine hydrate, respectively, has been investigated. Three new coordination polymers were prepared and fully characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. The compound [Co(micro(3)-H(2)bbh)(phen)](n)() (1) (triclinic space group P with a = 9.762(4) A, b = 10.169(4) A, c = 11.143(4) A, alpha = 80.96(3) degrees, beta = 64.49(3) degrees, gamma = 71.88(3) degrees, Z = 2) was synthesized from the reaction of CoCl(2).6H(2)O, H(4)bta (=benzene-1,2,4,5-tetracarboxylic acid), N(2)H(4).H(2)O, phen (=1,10-phenanthroline) and H(2)O, and consists of one-dimensional double-chains. [Co(micro(4)-H(2)bbh)(H(2)O)(2)](n)() (2) (monoclinic space group P2(1)/c with a = 6.8687(5) A, b = 7.5943(6) A, c = 10.0401(6) A, beta = 95.250(4) degrees, Z = 2) was generated by the combination of CoCl(2).6H(2)O, H(4)bta, N(2)H(4).H(2)O, and H(2)O. It adopts a three-dimensional structural motif in the solid state with channels consisting of 20-numbered rings. [Co(micro(3)-Hbcbh)(bpy)](n)() (3) (monoclinic space group Cc with a = 9.9464(13) A, b = 23.685(5) A, c = 7.9491 (16) A, beta = 117.677(13) degrees, Z = 4) was obtained from the mixture of CoCl(2).6H(2)O, N(2)H(4).H(2)O, H(3)btc (=benzene-1,2,4-tricarboxylic acid), bpy (=2,2'-dipyridyl), and H(2)O, and features a two-dimensional plane. The results of magnetic research indicate that there exist antiferromagnetic interactions between Co centers in both compounds 1 and 2.