Gelatin-mediated gallium-doped SrHA composite coatings with sequential antimicrobial and osteogenic functions for infected bone defect repair.

In this study, gallium- and gelatin-modified strontium-doped hydroxyapatite (SrHA-Gel-Ga) bilayer coatings were prepared on titanium substrates by electrodeposition and spin-coating techniques. The results showed that gallium and gelatin were uniformly doped into the SrHA coatings, which exhibited good hydrophilicity and bioactivity. Furthermore, SrHA-Gel-Ga demonstrated good antimicrobial properties against E. coli and S. aureus, especially S. aureus. The co-doping of Sr and gelatin in the coatings was effective in mitigating the cytotoxicity of Ga. SrHA-Gel-Ga was better able to promote the adhesion, proliferation and early differentiation of MC3T3-E1 cells. This study provides a new strategy for the development of anti-infective bone repair coatings.

Rational Design of Nanogels for Overcoming the Biological Barriers in Various Administration Routes.

Nanogels have been identified as outstanding nanocarrier candidates for drug delivery due to their desirable physiochemical properties and versatile applicability for diverse therapeutic molecules and imaging probes. One of the main challenges that hinder the clinical translation of nanogels is the low efficiency of drug delivery to the target sites because of the complex biological barriers during the in vivo journey. The purpose of this review is to examine and summarize the recent advances on the rational design and structural modulation of nanogels to overcome the barriers and challenges on the way to the site of action following various dosing modes. In particular, the functional moieties or domains have been incorporated in the nanogels, allowing them to spontaneously regulate their structure and physiochemical properties to cross one or more of the multifaceted barriers. In addition, the future perspectives are presented with regards to opportunities and challenges for the precise and efficient therapeutic use of nanogel formulations.

[Preparation and Characterization of Manganese and Fluorine Co-Modified Hydroxyapatite Composite Coating].

Titanium and titanium alloys have been widely used as orthopedic, dental implants and cardiovascular stents owing to their superior physical properties. However, titanium surface is inherently bio-inert, thus could not form efficient osseointegration with surrounding bone tissue. Therefore, to improve the surface property of titanium implant is significantly important in clinical application. Manganese and fluorine co-doped hydroxyapatite (FMnHAP) coatings were prepared on titanium substrate by electrochemical deposition technique. The as-prepared coatings were examined by scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) tests. The results indicated that the FMnHAP coatings take the morphology of nanoscale-villous-like, the composite coating becomes more compact. The FTIR test indicated that the symmetry of bending vibration modes of hydroxyl changed, simulated body fluid immersion test proved that the FMnHAP coatings had induce carbonate-apatite formation, indicating that the composite coating possess excellent biocompatibility. In the electrochemical corrosion testing, the FMnHAP coatings showed stronger corrosion resistance than pure Ti.

Layer-by-layer self-assembly coatings on strontium titanate nanotubes with antimicrobial and anti-inflammatory properties to prevent implant-related infections.

One way to effectively address endophyte infection and loosening is the creation of multifunctional coatings that combine anti-inflammatory, antibacterial, and vascularized osteogenesis. This study started with the preparation of strontium-doped titanium dioxide nanotubes (STN) on the titanium surface. Next, tannic acid (TA), gentamicin sulfate (GS), and pluronic F127 (PF127) were successfully loaded into the STN via layer-by-layer self-assembly, resulting in the STN@TA-GS/PF composite coatings. The findings demonstrated the excellent hydrophilicity and bioactivity of the STN@TA-GS/PF coating. STN@TA-GS/PF inhibited E. coli and S. aureus in vitro to a degree of roughly 80.95 % and 92.45 %, respectively. Cellular investigations revealed that on the STN@TA-GS/PF surface, the immune-system-related RAW264.7, the vasculogenic HUVEC, and the osteogenic MC3T3-E1 showed good adhesion and proliferation activities. STN@TA-GS/PF may influence RAW264.7 polarization toward the M2-type and encourage MC3T3-E1 differentiation toward osteogenesis at the molecular level. Meanwhile, the STN@TA-GS/PF coating achieved effective removal of ROS within HUVEC and significantly promoted angiogenesis. In both infected and non-infected bone defect models, the STN@TA-GS/PF material demonstrated strong anti-inflammatory, antibacterial, and vascularization-promoting osteogenesis properties. In addition, STN@TA-GS/PF had good hemocompatibility and biosafety. The three-step process used in this study to modify the titanium surface for several purposes gave rise to a novel concept for the clinical design of antimicrobial coatings with immunomodulatory properties.

Sorption enhancement of Cr(VI) from aqueous solution by polyaniline confined in three-dimensional network of composite porous hydrogel.

Hexavalent chromium Cr(VI) is a typical harmful pollutant, which is carcinogenic or mutagenic to aquatic animals and humans. In this study, sepiolite/humic acid/polyvinyl alcohol@ polyaniline (SC/HA/PVA@PANI) composite porous hydrogel adsorbent was synthesized by Pickering emulsion template in situ chemical oxidative polymerization for adsorption of Cr(VI) from aqueous solution. The in situ polymerization of aniline at the Pickering emulsion interface and the unique three-dimensional network structure of the hydrogel act as an effective "confinement" for the growth of the polymer. The porous structure of the material acts as a water channel, which effectively accelerates the binding of the adsorbate to the adsorption sites, and significantly improves the adsorption rate and adsorption capacity. The adsorption capacity of PANI for Cr(VI) confined in three-dimensional network of composite porous SC/HA/PVA@PANI hydrogel reached 1180.97 mg/g-PANI, which increased about 27-fold compared the adsorption capacity of pure PANI (43.48 mg/g). It is shown that the experimental design effectively avoids the agglomeration of PANI and improves its potential adsorption performance. In addition, the analysis of FESEM-EDX, FT-IR, and XPS spectra before and after adsorption confirmed that the main adsorption mechanisms of Cr(VI) on SC/HA/PVA@PANI included ion exchange, electrostatic attraction, and redox reaction. In conclusion, SC/HA/PVA@PANI has good stability and excellent adsorption performance, which is a new type of Cr(VI) ion adsorbent with great potential.

Meyerozyma guilliermondii promoted the deposition of GSH type lignin by activating the biosynthesis and polymerization of monolignols at the wounds of potato tubers.

Lignin is a crucial component in the wound tissue of tubers. The biocontrol yeast Meyerozyma guilliermondii increased the activities of phenylalanine ammonia lyase, cinnamate-4-hydroxylase, 4-coenzyme coenzyme A ligase, and cinnamyl alcohol dehydrogenase, and elevated the levels of coniferyl, sinapyl, and p-coumaryl alcohol. The yeast also enhanced the activities of peroxidase and laccase, as well as the content of hydrogen peroxide. The lignin promoted by the yeast was identified as guaiacyl-syringyl-p-hydroxyphenyl type using Fourier transform infrared spectroscopy and two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance. Furthermore, a larger signal area for G2, G5, G'6, S2, 6, and S'2, 6 units was observed in the treated tubers, and the G'2 and G6 units were only detected in the treated tuber. Taken together, M. guilliermondii could promote deposition of guaiacyl-syringyl-p-hydroxyphenyl type lignin by activating the biosynthesis and polymerization of monolignols at the wounds of potato tubers.

Development of novel hydrophilic and antibacterial silicone rubber impression material for dental application.

OBJECTIVES: This investigation aimed to develop a novel hydrophilic and antibacterial silicone rubber impression material for dental application. METHODS: The basic formula of the new silicone rubber was determined on a preliminary study, and 6% polyether modified silicone oil was added as wetting agent to provide the hydrophilicity. No-vel nano-antibacterial inorganic fillers containing quaternary ammonium salt with long chain alkyl were incorporated into the hydrophilic silicone rubber impression materials at a mass fraction of 0%, 1%, 2%, 3%, 4%, or 5%. A commercial silicone rubber impression material was used as control. The mechanical properties, wettability, detail reproducibility, dimensional stability, and mixing time of silicone rubber materials were measured. Thin-film adhesion method and cell counting kit-8 method were used to detect the antibacterial property and cytotoxicity. Scanning electron microscopy (SEM) was chosen to observe the micromorphology of the novel silicone rubber. RESULTS: When the content of antibacterial filler exceeded 4%, the mechanical properties of the new silicone rubber decreased significantly (P<0.05). Compared with those of the control group, the contact angle and linear size change rate of different groups had no significant change at different time nodes, and the detail reproducibility was intact (P>0.05). The addition of antibacterial fillers had no significant effect on the mixing time (P>0.05). Adding 4% antibacterial fillers could result in the antibacterial rate of 95.26%, showing good antibacterial properties. No significant difference was found in the cytotoxicity of all groups (P>0.05). The SEM pictures of the cross section of the silicone rubber sample showed that the fillers had good compatibility with the silicone rubber matrix and distributed in the matrix evenly. CONCLUSIONS: A novel silicone rubber impression material containing 6% polyether modified silicone oil could obtain promising hydrophilic and antibacterial properties after being added with 4% antibacterial inorganic fillers.

Environmental stability and cytotoxicity of layered black phosphorus modified with Polyvinylpyrrolidone and Zeolitic Imidazolate Framework-67.

Layered black phosphorus (LBP) is regarded as a promising two-dimensional nanomaterial in various application fields. As bare LBP is unstable in humid environment, many modification methods have been developed recently. However, environmental risks of modified LBP nanomaterials are largely unknown. Herein, by sonication and in-situ surface-confined synthesis, polyvinylpyrrolidone (PVP) coated LBP (LBP/PVP), and zeolitic imidazolate framework-67 (ZIF-67) modified LBP (LBP/PVP-ZIF-67) nanomaterials were synthesized. Environmental stability and toxicity of the modified nanomaterials were compared with bare LBP. Results show that LBP/PVP-ZIF-67 exhibits excellent photothermal performance, and higher potential in electrochemical hydrogen evolution than bare LBP or LBP/PVP. Characteristic visible light absorbance at 593 nm was introduced into the nanomaterial by ZIF-67. LBP/PVP has stability in aqueous environment or cytotoxicity similar to LBP. LBP/PVP-ZIF-67 is completely stable in water within 120 h, in contrast to over 30% degradation of LBP or LBP/PVP. More than 50% of LBP in the LBP/PVP-ZIF-67 can degrade to dissolvable phosphorus in oxygenated water after 17 days, indicating the nanomaterial will not be persistent in the environment. Moreover, modification with ZIF-67 can reduce cytotoxicity of LBP. Therefore, this study develops a safe strategy to modify LBP and provides basic information for ecological risk assessment of LBP based materials.

Hydroxyl radical oxidation of cyclic methylsiloxanes D4 ∼ D6 in aqueous phase.

Cyclic methylsiloxanes (CMS) were listed as candidates of substances of very high concerns in 2018 by the REACH. These compounds can enter environmental waters, and potentially cause harmful effects to aquatic organisms and human beings. Until now, reaction mechanisms of these pollutants with hydroxyl radicals (HO) in aqueous phase were unknown. In this study, reaction mechanisms of three typical CMS (D4 ∼ D6) with HO in aqueous phase were investigated by employing both UV/H2O2 experiments and density functional theoretical calculations. Bimolecular reaction rate constants (kHO·) of D4 ∼ D6 with HO were determined as kHO·(D4) = 8kHO·(D5) = 12kHO·(D6) = 6.6 × 108 L mol-1 s-1. Half-lives of HO oxiding D4 ∼ D6 ranged from 12 to 140 days at [HO] = 10-15 mol L-1 in sunlit surface water, and were comparable to (D4, D5) or much shorter (D6) than hydrolytic half-lives. The reactivity to HO decreased with the increasing size of siloxane ring in aqueous phase, in an order totally opposite to that in gaseous phase. Calculation results indicated that HO oxidation of the three CMS proceeded spontaneously through an exothermic H-abstraction process at the first step. Water molecules participated into H-abstraction of CMS and caused energy barrier of D5 higher than that of D4. Thus, H-bonds formed by water molecules were responsible for the reverse reactivity of CMS in aqueous phase. This work provided basic evidences suggesting environmental persistence of CMS in aqueous phase completely different from that in gaseous phase.

Amphiphilic random glycopolymer based on phenylboronic acid: synthesis, characterization, and potential as glucose-sensitive matrix.

This study is devoted to developing amphiphilic, random glycopolymers based on phenylboronic acid, which self-assemble to form nanoparticles (NPs), as a glucose-sensitive agent. Maleimide-glucosamine was copolymerized with 3-acryl aminophenylboronic acid in methanol at 70 degrees C. Using the nanoprecipitation method, NPs with a narrow size distribution were successfully generated. Transmission electron microscopic analysis showed that the NPs were well dispersed as individual, spherically shaped particles. The swelling behavior of the NPs and the in vitro release profiles of insulin at different glucose concentrations revealed definite glucose sensitivity of the glycopolymers. Further, circular dichroism spectroscopy demonstrated that the overall tertiary structure of the released insulin was not altered compared with standard insulin. The analysis of relative cell proliferation suggested that the glycopolymer NPs had good biocompatibility. The glycopolymers that responded to changes in the glucose concentration of the surrounding environment are being aimed for use in self-regulated insulin delivery.

Biofunctional Sr- and Si-loaded titania nanotube coating of Ti surfaces by anodization-hydrothermal process.

BACKGROUND: Two frequent problems associated with titanium (Ti) surfaces of bone/dental implants are their corrosion and lack of native tissue integration. METHODS: Here, we present an anodization-hydrothermal method for coating Ti surfaces with a layer of silicon (Si)- and strontium (Sr)-loaded titania nanotubes (TNs). The Ti surfaces coated with such a layer (Si-Sr-TNs) were characterized with different techniques. RESULTS: The results indicate that the Si4+ and Sr2+ ions were evenly incorporated into the TNs and that the Si-Sr-TN layer provides good protection against corrosive media like simulated body fluid. The excellent cytocompatibility of the coating was confirmed in vitro by the significant growth and differentiation of MC3T3-E1 osteoblastic cells. CONCLUSION: Being easily and economically fabricated, the Si-Sr-TN surfaces may find their niche in clinical applications, thanks to their excellent biological activity and corrosion resistance.

Interactions of polymeric drug carriers with DDT reduce their combined cytotoxicity.

Attention has been paid to the environmental distribution and fate of nanomedicines. However, their effects on the toxicity of environmental pollutants are lack of knowledge. In this study, the negatively charged poly (ethylene glycol)-b-poly (L-lactide-co-glycolide) (mPEG-PLA) and positively charged polyethyleneimine-palmitate (PEI-PA) nanomicelles were synthesized and served as model drug carriers to study the interaction and combined toxicity with dichlorodiphenyltrichloroethane (DDT). DDT exerted limited effect on the biointerfacial behavior of mPEG-PLA nanomicelles, whereas it significantly mitigated the attachment of PEI-PA nanomicelles on the model cell membrane as monitored by quartz crystal microbalance with dissipation (QCM-D). The cytotoxicity of DDT towards NIH 3T3 cells was greatly decreased by either co-treatment or pre-treatment with the nanomicelles according to the results of real-time cell analysis (RTCA). The cell viability of NIH 3T3 exposed to DDT was increased up to 90% by the co-treatment with mPEG-PLA nanomicelles. Three possible reasons were proposed: (1) decreased amount of free DDT in the cell culture medium due to the partitioning of DDT into nanomicelles; (2) mitigated cellular uptake of nanomicelle-DDT complexes due to the complex agglomeration or electrostatic repulsion between complexes and cell membrane; (3) detoxification effect in the lysosome upon endocytosis of nanomicelle-DDT complexes.

Nanostructured Ag+-substituted fluorhydroxyapatite-TiO2 coatings for enhanced bactericidal effects and osteoinductivity of Ti for biomedical applications.

BACKGROUND: Poor mechanical properties, undesirable fast dissolution rate, and lack of antibacterial activity limit the application of hydroxyapatite (HA) as an implant coating material. To overcome these limitations, a hybrid coating of Ag+-substituted fluorhydroxyapatite and titania nanotube (TNT) was prepared. METHODS: The incorporation of silver into the HA-TiO2 hybrid coating improves its antimicrobial properties. The addition of F as a second binary element increases the structural stability of the coating. The TNT/F-and-Ag-substituted HA (FAgHA) bilayer coating on the Ti substrate was confirmed by X-ray diffraction, scanning electron microscope, energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). RESULTS: The results indicate that the FAgHA/TNT nanocomposite coating has a dense and uniform morphology with a nano-rod-like structure. The solubility measurement result shows that the substitution of F- ions into the AgHA structure has a positive effect on the dissolution resistance of HA. The adhesion strength of FAgHA/TNT has significantly increased because of the interlocking of the roughened surface with nano-rod-like particles that entered into the voids of the TiO2 nanotubes. Compared with that of the bare Ti, the corrosion current density of FAgHA/TNT-coated Ti substrate decreased from 3.71 to 0.18 µA, and its corrosion resistance increased by almost two orders of magnitude. Moreover, despite pure HA, the FAgHA killed all viable Staphylococcus aureus after 24 hours of incubation. Although the fabricated FAgHA/TNT coating is hydrophobic, it induced deposition of the typical spherical apatite when immersed in a simulated body fluid (SBF); the osteoblasts spread very well on the surface of the coating. In addition, in vitro cell culture tests demonstrated cell viability and alkaline phosphatase (ALP) similar to pure HA, which indicated good cytocompatibility. Interestingly, compared with bare Ti, FAgHA/TNT-coated Ti surface was innocent for cell vitality and even more beneficial for cell osteogenesis in vitro. CONCLUSION: Enhancing the osseointegration and preventing infection in implants, the FAgHA/TNT-coated Ti makes implants more successful.

Polyglycerol-opioid conjugate produces analgesia devoid of side effects.

Novel painkillers are urgently needed. The activation of opioid receptors in peripheral inflamed tissue can reduce pain without central adverse effects such as sedation, apnoea, or addiction. Here, we use an unprecedented strategy and report the synthesis and analgesic efficacy of the standard opioid morphine covalently attached to hyperbranched polyglycerol (PG-M) by a cleavable linker. With its high-molecular weight and hydrophilicity, this conjugate is designed to selectively release morphine in injured tissue and to prevent blood-brain barrier permeation. In contrast to conventional morphine, intravenous PG-M exclusively activated peripheral opioid receptors to produce analgesia in inflamed rat paws without major side effects such as sedation or constipation. Concentrations of morphine in the brain, blood, paw tissue, and in vitro confirmed the selective release of morphine in the inflamed milieu. Thus, PG-M may serve as prototype of a peripherally restricted opioid formulation designed to forego central and intestinal side effects.

Functionalized nanogels carrying an anticancer microRNA for glioblastoma therapy.

Glioblastoma Multiforme (GBM) is one of the most aggressive forms of all cancers. The median survival with current standard-of-care radiation and chemotherapy is about 14months. GBM is difficult to treat due to heterogeneity in cancer cell population. MicroRNA-based drugs have rapidly become a vast and burgeoning field due to the ability of a microRNA (miRNA) to target many genes involved in key cellular pathways. However, in vivo delivery of miRNA remains a crucial challenge for its therapeutic success. To bypass this shortcoming, we designed polymeric nanogels (NGs), which are based on a polyglycerol-scaffold, as a new strategy of miRNA delivery for GBM therapy. We focused on miR-34a, which is known for its key role in important oncogenic pathways and its tumor suppression ability in GBM and other cancers. We evaluated the capability of six NG derivatives to complex with miR-34a, neutralize its negative charge and deliver active miRNA to the cell cytoplasm. Human U-87 MG GBM cells treated with our NG-miR-34a nano-polyplexes showed remarkable downregulation of miR-34a target genes, which play key roles in the regulation of apoptosis and cell cycle arrest, and induce inhibition of cells proliferation and migration. Administration of NG-miR-34a nano-polyplexes to human U-87 MG GBM-bearing SCID mice significantly inhibited tumor growth as opposed to treatment with NG-negative control miR polyplex or saline. The comparison between different polyplexes highlighted the key features for the rational design of polymeric delivery systems for oligonucleotides. Taken together, we expect that this new therapeutic approach will pave the way for safe and efficient therapies for GBM.

Multi-stage, charge conversional, stimuli-responsive nanogels for therapeutic protein delivery.

A boronate ester crosslinked zwitterionic nanogel (NGCA) with ATP/pH-sensitivity has been developed with an inverse nanoprecipitation technique to achieve a two-stage charge conversion that responds to tumor extracellular conditions (pH 6.5-6.8) and an intracellular acidic environment (pH 5-6). Cationic cytochrome C (CC), a therapeutic protein, has been encapsulated into NGCA through inverse nanoprecipitation via electrostatic interactions to form protein-loaded nanogel (NGCA-CC). By adjusting the ratio of the amino and carboxyl groups in the nanogels, negatively charged nanogels that are safer under physiological conditions (pH 7.4) can convert their surface charge to positive at tumor extracellular pH, which enhance their cellular uptake efficiency. The citraconic amide formed from citraconic anhydride and amine can be cleaved in the intracellular acidic organelles to expose more amino groups and facilitate endosomal escape. The release of CC is accelerated in the presence of 5 mM ATP or under acidic conditions. Confocal laser scanning microscopy (CLSM) and flow cytometry have shown that NGCA-CC's cell uptake is higher at pH 6.5 than at pH 7.4. MTT and real-time cell analysis (RTCA) have illustrated that there is more toxicity at pH 6.5 than at pH 7.4. The apoptosis process induced by CC was determined by flow cytometry.

Boronate cross-linked ATP- and pH-responsive nanogels for intracellular delivery of anticancer drugs.

A novel adenosine-5'-triphosphate (ATP) and pH dual-responsive degradable nanogel (NG) system are developed based on the complexation of 1,2-diols in dendritic polyglycerol (dPG), and boronic acids, which are conjugated with dPG as the macromolecular cross-linker. The NG is formed by a mild and surfactant-free inverse nanoprecipitation method. An anticancer drug, methotrexate (MTX), is coprecipitated with the macromolecular precursors and cross-linkers to form MTX-loaded NG (NG-MTX) with a loading capacity of 13 wt%. The size of NG is controllable from 100 to 300 nm, which is suitable for the enhanced permeation and retention (EPR) effect and can be degraded into small fragments that are within the clearance limitation in the presence of 5 × 10(-3) m ATP or at pH 4 after 24 h. Increasing ATP concentrations and decreasing pH values of the release medium accelerate the release of MTX. Both the real-time cell analysis (RTCA) and MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) results show no cytotoxic effect of NG and a dose-dependent effect of NG-MTX on HeLa cells as well as MCF-7 cells. The fluorescein isothiocyanate (FITC)-labeled NG (FITC-NG) exhibits a time-dependent intracellular uptake tendency and cell organelle permeability as determined by confocal laser scanning microscopy (CLSM) or flow cytometry.

A facile approach for dual-responsive prodrug nanogels based on dendritic polyglycerols with minimal leaching.

A novel pH and redox dual-responsive prodrug nanogel was prepared by an inverse nanoprecipitation method, which is mild and surfactant free, and based on a thiol-disulfide exchange reaction and thiol-Michael addition reaction. Highly biocompatible hyperbranched polyglycerol (hPG) was cross-linked with disulfide bonds, to obtain biodegradable nanogels, which could be degraded under intracellular reductive conditions. Doxorubicin (DOX) was conjugated to the biodegradable nanogel matrix via an acid-labile hydrazone linker. This is the first dual-responsive prodrug nanogel system that shows very low unspecific drug leaching, but efficient intracellular release of the payload triggered by the intracellular conditions. Two different prodrug nanogels were prepared with a size of approximately 150nm, which is big enough to take the advantage of the enhanced permeation and retention (EPR) effect in tumor tissue. Cell culture analysis by microscopy and flow cytometry revealed that the prodrug nanogels were efficiently internalized by tumor cells. Distinct release profiles of DOX were achieved by adjusting the nanogel architecture, and online detection of cytotoxicity showed that, unlike free DOX, the dual-responsive prodrug nanogels exhibited a delay in the onset of toxicity, indicating the different uptake mechanism and the need for prodrug activation to induce cell death.

Hydrotropic polymeric mixed micelles based on functional hyperbranched polyglycerol copolymers as hepatoma-targeting drug delivery system.

Mixed copolymer nanoparticles (NPs) self-assembled from ß-cyclodextrin-grafted hyperbranched polyglycerol (HPG-g-CD) and lactobionic acid (LA)-grafted hyperbranched polyglycerol (HPG-g-LA) were applied as carriers for a hydrophobic antitumor drug, paclitaxel (PTX), achieving hepatocellular carcinoma-targeted delivery. The resulting NPs exhibited high drug loading capacity and substantial stability in aqueous solution. In vitro drug release studies demonstrated a controlled drug release profile with increased release at acidic pH. Remarkably, tumor proliferation assays showed that PTX-loaded mixed copolymer NPs inhibited asialoglycoprotein (ASGP) receptor positive HepG2 cell proliferation in a concentration-dependent manner in comparison with ASGP receptor negative BGC-823 cells. Moreover, the competition assay demonstrated that the small molecular LA inhibited the cellular uptake of the PTX-loaded mixed copolymer NPs, indicating the ASGP receptor-mediated endocytosis in HepG2 cells. In addition, the intracellular uptake tests by confocal laser scanning microscopy showed that the mixed copolymer NPs were more efficiently taken up by HepG2 cells compared with HPG-g-CD NPs. These results suggest a feasible application of the mixed copolymer NPs as nanocarriers for hepatoma-targeted delivery of potent antitumor drugs.

Surfactant free preparation of biodegradable dendritic polyglycerol nanogels by inverse nanoprecipitation for encapsulation and release of pharmaceutical biomacromolecules.

In this paper we report a novel approach to generate biodegradable polyglycerol nanogels on different length scales. We developed a mild, surfactant free inverse nanoprecipitation process to template hydrophilic polyglycerol nanoparticles. In situ crosslinking of the precipitated nanoparticles by bioorthogonal copper catalyzed click chemistry allows us to obtain size defined polyglycerol nanogels (100-1000nm). Biodegradability was achieved by the introduction of benzacetal bonds into the net points of the nanogel. Interestingly, the polyglycerol nanogels quickly degraded into low molecular weight fragments at acidic pH values, which are present in inflamed and tumor tissues as well as intracellular organelles, and they remained stable at physiological pH values for a long time. This mild approach to biodegradable polyglycerol nanogels allows us to encapsulate labile biomacromolecules such as proteins, including the therapeutic relevant enzyme asparaginase, into the protein resistant polyglycerol network. Enzymes were encapsulated with an efficacy of 100% and after drug release, full enzyme activity and structural integrity were retained. This new inverse nanoprecipitation procedure allows the efficient encapsulation and release of various biomacromolecules including proteins and could find many applications in polymer therapeutics and nanomedicine.