A Facile Strategy for Constructing Boron-Rich Polymer Nanoparticles via a Boronic Acid-Related Reaction

Tailor-Made Polysaccharides for Biomedical Applications

Polysaccharides (PSAs) are carbohydrate-based macromolecules widely used in the biomedical field, either in their pure form or in blends/nanocomposites with other materials. The relationship between structure, properties, and functions has inspired scientists to design multifunctional PSAs for various biomedical applications by incorporating unique molecular structures and targeted bulk properties. Multiple strategies, such as conjugation, grafting, cross-linking, and functionalization, have been explored to control their mechanical properties, electrical conductivity, hydrophilicity, degradability, rheological features, and stimuli-responsiveness. For instance, custom-made PSAs are known for their worldwide biomedical applications in tissue engineering, drug/gene delivery, and regenerative medicine. Furthermore, the remarkable advancements in supramolecular engineering and chemistry have paved the way for mission-oriented biomaterial synthesis and the fabrication of customized biomaterials. These materials can synergistically combine the benefits of biology and chemistry to tackle important biomedical questions. Herein, we categorize and summarize PSAs based on their synthesis methods, and explore the main strategies used to customize their chemical structures. We then highlight various properties of PSAs using practical examples. Lastly, we thoroughly describe the biomedical applications of tailor-made PSAs, along with their current existing challenges and potential future directions.

Boron Neutron Capture Therapy Enhanced by Boronate Ester Polymer Micelles: Synthesis, Stability, and Tumor Inhibition Studies

Boron neutron capture therapy (BNCT) targets invasive, radioresistant cancers but requires a selective and high B-10 loading boron drug. This manuscript investigates boron-rich poly(ethylene glycol)-block-(poly(4-vinylphenyl boronate ester)) polymer micelles synthesized via atom transfer radical polymerization for their potential application in BNCT. Transmission electron microscopy (TEM) revealed spherical micelles with a uniform size of 43 ± 10 nm, ideal for drug delivery. Additionally, probe sonication proved effective in maintaining the micelles' size and morphology postlyophilization and reconstitution. In vitro studies with B16-F10 melanoma cells demonstrated a 38-fold increase in boron accumulation compared to the borophenylalanine drug for BNCT. In vivo studies in a B16-F10 tumor-bearing mouse model confirmed enhanced tumor selectivity and accumulation, with a tumor-to-blood (T/B) ratio of 2.5, surpassing BPA's T/B ratio of 1.8. As a result, mice treated with these micelles experienced a significant delay in tumor growth, highlighting their potential for BNCT and warranting further research.

Efficient pH-Responsive Nano-Drug Delivery System Based on Dynamic Boronic Acid/Ester Transformation

Chemotherapy is currently one of the most widely used treatments for cancer. However, traditional chemotherapy drugs normally have poor tumor selectivity, leading to insufficient accumulation at the tumor site and high systemic cytotoxicity. To address this issue, we designed and prepared a boronic acid/ester-based pH-responsive nano-drug delivery system that targets the acidic microenvironment of tumors. We synthesized hydrophobic polyesters with multiple pendent phenylboronic acid groups (PBA-PAL) and hydrophilic PEGs terminated with dopamine (mPEG-DA). These two types of polymers formed amphiphilic structures through phenylboronic ester linkages, which self-assembled to form stable PTX-loaded nanoparticles (PTX/PBA NPs) using the nanoprecipitation method. The resulting PTX/PBA NPs demonstrated excellent drug encapsulation efficiency and pH-triggered drug-release capacity. In vitro and in vivo evaluations of the anticancer activity of PTX/PBA NPs showed that they improved the pharmacokinetics of drugs and exhibited high anticancer activity while with low systemic toxicity. This novel phenylboronic acid/ester-based pH-responsive nano-drug delivery system can enhance the therapeutic effect of anticancer drugs and may have high potential for clinical transformations.

Recent progress and applications of poly(beta amino esters)-based biomaterials

Poly(beta-amino esters, PBAEs) are a promising class of cationic polymers synthesized from diacrylates and amines via Michael addition. Recently, PBAEs have been widely developed for drug delivery, immunotherapy, gene therapy, antibacterial, tissue engineering and other applications due to their convenient synthesis, good bio-compatibility and degradation properties. Herein, we mainly summarize the recent progress in the PBAEs synthesis and their applications. The amine groups of PBAEs could be protonated in low pH environment, exhibiting proton sponge and pH-sensitive abilities. Furthermore, the positive PBAEs can interact with negative genes via electrostatic interactions for efficient delivery of nucleic acids. Moreover, positive PBAEs could also directly kill bacteria by disrupting their membranes at high doses. Finally, PBAEs can augment the immune responses, and improve the bioactivity of hydrogels in tissue engineering.

pH-sensitive and tumor-targeting nanogels based on ortho ester-modified PEG for improving the in vivo anti-tumor efficiency of doxorubicin

In this study, we aim to develop the pH-sensitive and tumor-targeting nanogels based on the co-polymerization of three terminal allyl-functionalized components, including ortho ester-conjugated mPEG (mPEG-MOE), ortho ester crosslinker (OEAM) and phenylboronic acid (APBA). The hybrid nanogels displayed a typical spherical structure with a diameter around 200 nm observed by dynamic light scattering (DLS) and scanning electron microscopy (SEM). The prepared nanogels possessed a good stability in neutral conditions, while displayed pH-triggered drug release profiles. Furthermore, in vitro study of cellular uptake and cytotoxicity indicated that the nanogels possessed the highest drug accumulation and cytotoxicity against EMT6 cells. In vivo antitumor examination suggested that these nanogels brought out excellent efficacy in enhancing drug concentration, restraining tumor growth, and prolonged the survival time of tumor-bearing mice. Thus, the prepared multi-functional nanogels possess great potentials for drug delivery in tumor treatment.

Phenylboronic acid-conjugated chitosan nanoparticles for high loading and efficient delivery of curcumin

In order to achieve high loading and efficient delivery of curcumin, phenylboronic acid-conjugated chitosan nanoparticles were prepared by a simple desolvation method. These nanoparticles exhibited a regular spherical shape with the average size about 200-230 nm and narrow size distribution, which were kinetically stable under physiological condition. Due to boronate ester formation between curcumin and phenylboronic acid groups in the nanoparticles, and the hydrogen bonding interactions between curcumin and nanocarriers, curcumin was successfully loaded into the nanoparticles with high drug loading content. These curcumin-loaded nanoparticles showed pH and reactive oxygen species (ROS)-triggered drug release behavior. In vitro cell experiments revealed that the blank nanoparticles were completely nontoxic to cultured cells, and the curcumin-loaded nanoparticles exhibited efficient antitumor efficiency against cancer cells. Moreover, the drug-loaded nanoparticles performed an enhanced growth inhibition in three-dimensional multicellular tumor spheroids. Thus, these nanocarriers would be a promising candidate for curcumin delivery in tumor treatment.

Boron-rich, cytocompatible block copolymer nanoparticles by polymerization-induced self-assembly

A new methacrylic boronate ester is synthesized and exploited to produce biocompatible nanoparticles with a boron-rich core by PISA.

Targeting and microenvironment-improving of phenylboronic acid-decorated soy protein nanoparticles with different sizes to tumor

It is essential for nanoparticles to delivery drugs accurately and penetrate deeply to tumor. However, complicated tumor microenvironment such as elevated tumor interstitial fluid pressure (IFP) and solid stress reduces the transport efficiency of nanomedicines in tumor.

Methods: We herein report a drug delivery system of phenylboronic acid-decorated soy protein nanoparticles with the size of 30 nm, 50 nm and 150 nm. In vitro examinations including cytotoxicity, cellular uptake and penetration in multicellular tumor spheroids and in vivo observations including IFP and tumor solid stress measurements and antitumor activity were performed.

Results: It was found that phenylboronic acid moiety could endow the nanoparticles actively targeting affinity to sialic acid (SA) which overexpressed in tumor cells. Simultaneously soy protein could improve tumor microenvironment such as reduction of IFP and tumor stress. Among the soy protein nanoparticles with different sizes, 30 nm-sized nanoparticles showed the best cellular uptake and highest cytotoxicity in vitro after loading doxorubicin (DOX). In vivo, 30 nm-sized nanoparticles showed the best tumor microenvironment improvement efficiency, leading to the enhanced drug accumulation and antitumor efficiency when combination with DOX.

Conclusion: Our study introduces a bioactive nanoparticulate design strategy to actively target and significantly improve tumor microenvironment for enhanced cancer therapy.

Phenylboronic acid-incorporated elastin-like polypeptide nanoparticle drug delivery systems

Packaging hydrophobic drugs into nanoparticles can improve their aqueous solubility, tumor-specific accumulation and therapeutic effect.

Enzymatic Degradation of Oligo(ε-caprolactone)s End-Capped with Phenylboronic Acid Derivatives at the Air-Water Interface

The influence of terminal functionalization of oligo(ε-caprolactone)s (OCL) with phenylboronic acid pinacol ester or phenylboronic acid on the enzymatic degradation behavior at the air-water interface is investigated by the Langmuir monolayer degradation technique. While the unsubstituted OCL immediately degrades after injection of the enzyme lipase from Pseudomonas cepacia, enzyme molecules are incorporated into the films based on end-capped OCL before degradation. This incorporation of enzymes does not inhibit or suppress the film degradation, but retards it significantly. A specific binding of lipase to the polymer monolayer allows studying the enzymatic activity of bound proteins and the influence on the degradation process. The functionalization of a macromolecule with phenyl boronic acid groups is an approach to investigate their interactions with diol-containing biomolecules like sugars and to monitor their specified impact on the enzymatic degradation behavior at the air-water interface.

Folic acid-modified soy protein nanoparticles for enhanced targeting and inhibitory

Soy protein isolate (SPI) was hydrolyzed by compound enzymes to give water soluble low molecular soy protein (SP). SP and folic acid (FA) modified SP was polymerized with N-3- acrylamidophenylboronic acid (APBA) monomer in aqueous solution to give SP nanoparticles (SP NPs) and FA modified nanoparticles (FA-SP NPs), respectively. These NPs display excellent stability in different conditions, and have a uniform spherical shape with a diameter around of 200nm. Doxorubicin (DOX) was then successfully loaded into SP and FA-SP NPs with a desirable loading content of 13.33% and 16.01%, respectively. The cellular uptake and cytotoxicity of DOX-loaded SP NPs and FA-SP NPs were investigated using the two-dimensional (2D) monolayer cell model and three-dimensional (3D) multicellular spheroids (MCs). In vivo, tumor accumulation and growth inhibitory were then examined using H22 tumor-bearing mice. All these results demonstrated that conjugation of FA can efficiently enhance SP-based NPs' tumor accumulation and antitumor effect.

Phenylboronic Acid-Mediated Tumor Targeting of Chitosan Nanoparticles

The phenylboronic acid-conjugated chitosan nanoparticles were prepared by particle surface modification. The size, zeta potential and morphology of the nanoparticles were characterized by dynamic light scattering, zeta potential measurement and transmission electron microscopy. The cellular uptake, tumor penetration, biodistribution and antitumor activity of the nanoparticles were evaluated by using monolayer cell model, 3-D multicellular spheroid model and H22 tumor-bearing mice. The incorporation of phenylboronic acid group into chitosan nanoparticles impart a surface charge-reversible characteristic to the nanoparticles. In vitro evaluation using 2-D and 3-D cell models showed that phenylboronic acid-decorated nanoparticles were more easily internalized by tumor cells compared to non-decorated chitosan nanoparticles, and could deliver more drug into tumor cells due to the active targeting effect of boronic acid group. Furthermore, the phenylboronic acid-decorated nanoparticles displayed a deeper penetration and persistent accumulation in the multicellular spheroids, resulting in better inhibition growth to multicellular spheroids than non-decorated nanoparticles. Tumor penetration, drug distribution and near infrared fluorescence imaging revealed that phenylboronic acid-decorated nanoparticles could penetrate deeper and accumulate more in tumor area than non-decorated ones. In vivo antitumor examination demonstrated that the phenylboronic acid-decorated nanoparticles have superior efficacy in restricting tumor growth and prolonging the survival time of tumor-bearing mice than free drug and drug-loaded chitosan nanoparticles.

RGD-peptide conjugated inulin-ibuprofen nanoparticles for targeted delivery of Epirubicin

Recently, chemotherapy-based polymeric nanoparticles have been extensively investigated for solid tumor treatment. Tumor targeted nanoparticles demonstrated great potential for improved accumulation in the tumor tissue, superior anticancer activity and reduced side effects. Thus, inulin-ibuprofen polymer was synthesized by esterification between inulin and ibuprofen, and RGD targeted epirubicin (EPB) loaded nanoparticles were prepared by the self-assembly of inulin-ibuprofen polymer and in situ encapsulation of EPB. RGD conjugated EPB loaded nanoparticles were characterized by dynamic light scattering (DLS) and transmission electron microscope (TEM). The EPB release from the nanoparticles showed pH-dependent profile and accelerated by the decreased pH value, which would favor the effective drug delivery in vivo. Intracellular uptake analysis suggested that RGD conjugated nanoparticles could be easily internalized by the cancer cells. In vitro cytotoxicity revealed that RGD conjugated EPB loaded nanoparticles exhibited the better antitumor efficacy compared with non-conjugated nanoparticles. More importantly, RGD conjugated EPB loaded nanoparticles showed superior anticancer effects and reduced toxicity than free EPB and non-conjugated nanoparticles by in vivo antitumor activity, EPB biodistribution and histology analysis.

Boronic acids for fluorescence imaging of carbohydrates

Carbohydrate biomarkers are particularly important targets for fluorescence imaging given their pivotal role in numerous important biological events. This review highlights the development of fluorescence imaging agents based on boronic acids.

Nanoscaled boron-containing delivery systems and therapeutic agents for cancer treatment

Significant efforts have recently been made to develop nanoscaled boron-containing delivery systems for improving drug delivery in cancer therapy. On one hand, borate ester chemistry has shown importance in ligand-mediated tumor targeting owing to the recognition ability of boronic acid to polyol residues in cell membranes. In particular, the phenylboronic acid-functionalized nanocarriers for specific targeting to sialic acid groups which are overexpressed on tumor cells have made great achievements. On the other hand, nanoscaled boron neutron capture therapy agents show growing potential in efficiently transporting boron to tumor. The current review outlines the recent developments in the application of borate ester chemistry in tumor targeting by nanoparticles, then summarizes recent work on the development of boron-based nanomaterials as boron neutron capture therapy agents.

β-Cyclodextrin functionalized magnetic mesoporous silica colloid for cholesterol separation

Although cholesterol plays significant biochemical function in the human body, excess of it leads to various disorders, and thus, its control/separation is important in medical science and food industries. However, efficient and selective separation of cholesterol is challenging because cholesterol often exists in microheterogeneous or insoluble forms in remote organ and exists with other chemicals/biochemicals. Here, we have described a colloidal magnetic mesoporous silica (MMS)-based approach for efficient separation of cholesterol in different forms. MMS is functionalized with β-cyclodextrin for selective binding with cholesterol via host-guest interaction. The colloidal form of MMS offers effective interaction with cholesterol of any form, and magnetic property of MMS offers easier separation of bound cholesterol. Functionalized MMS is efficient in separating cholesterol crystals, water-insoluble cholesterol, and the microheterogeneous form of cholesterol from milk or a cellular environment. Developed material can be used to remove cholesterol from a complex bioenvironment and extended for large-scale cholesterol separation from food.

Synthesis of drug-crosslinked polymer nanoparticles

A new kind of drug-crosslinked polymer nanoparticle was synthesized. The nanoparticles were composed by a phenylboronic acid modified 10-hydroxycamptothecin (the crosslinker) and 1,2-diol-rich PEG-PGMA diblock copolymer (the backbone), and crosslinked by phenylboronic ester bond.

Mucoadhesive and enzymatic inhibitory nanoparticles for transnasal insulin delivery

AIM

To develop a novel nanocarrier with mucoadhesion and enzymatic inhibition for transnasal insulin delivery. METHODS & METHODS: The physicochemical characterization of the nanoparticles included size and morphology, as well as mucoadhesion and enzymatic inhibition. The in vitro release of insulin from the nanoparticles was evaluated in 3 mg/ml glucose medium. The cytocompatibility of the nanoparticles was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The interactions of the nanoparticles with Caco-2 cells and nasal epithelia, and the effect of the nanoparticles on transnasal insulin delivery were estimated.

RESULTS

The nanoparticles were spherical in shape, with an average size of 100 nm, and presented strong enzymatic inhibitory activity and high mucin adsorption ability. The insulinloaded nanoparticles showed the rapid insulin release in 3 mg/ml glucose medium. The nanoparticles were noncytotoxic to Caco-2 cells. Furthermore, the insulin-loaded nanoparticles overcame mucosal barriers and significantly decreased plasma glucose levels.

Probing the nanostructure, interfacial interaction, and dynamics of chitosan-based nanoparticles by multiscale solid-state NMR

Chitosan-based nanoparticles (NPs) are widely used in drug and gene delivery, therapy, and medical imaging, but a molecular-level understanding of the internal morphology and nanostructure size, interface, and dynamics, which is critical for building fundamental knowledge for the precise design and efficient biological application of the NPs, remains a great challenge. Therefore, the availability of a multiscale (0.1-100 nm) and nondestructive analytical technique for examining such NPs is of great importance for nanotechnology. Herein, we present a new multiscale solid-state NMR approach to achieve this goal for the investigation of chitosan-poly(N-3-acrylamidophenylboronic acid) NPs. First, a recently developed (13)C multiple cross-polarization magic-angle spinning (MAS) method enabled fast quantitative determination of the NPs' composition and detection of conformational changes in chitosan. Then, using an improved (1)H spin-diffusion method with (13)C detection and theoretical simulations, the internal morphology and nanostructure size were quantitatively determined. The interfacial coordinated interaction between chitosan and phenylboronic acid was revealed by one-dimensional MAS and two-dimensional (2D) triple-quantum MAS (11)B NMR. Finally, dynamic-editing (13)C MAS and 2D (13)C-(1)H wide-line separation experiments provided details regarding the componential dynamics of the NPs in the solid and swollen states. On the basis of these NMR results, a model of the unique nanostructure, interfacial interaction, and componential dynamics of the NPs was proposed.

Boronic acid shell-crosslinked dextran-b-PLA micelles for acid-responsive drug delivery

Herein, 3-carboxy-5-nitrophenylboronic acid (CNPBA) shell-crosslinked micelles based on amphiphilic dextran-block-polylactide (Dex-b-PLA) are prepared and used for efficient intracellular drug deliveries. Due to the reversible pH-dependent binding with diols to form boronate esters, CNPBA modified Dex-b-PLA shows excellent pH-sensitivity. In neutral aqueous conditions, CNPBA-Dex-b-PLA forms shell-crosslinked micelles to enable DOX loading, while in acid conditions, the boronate esters hydrolyze and the micelles de-crosslink to release loaded DOX. In vitro release studies indicate that the release of the DOX cargo is minimized at physiological conditions, while there is a burst release in response to low pHs. The cell viability of CNPBA-Dex-b-PLA investigated by MTT assay was more than 90%, indicating that, as a drug delivery system, CNPBA-Dex-b-PLA has good cytocompatibility. These features suggest that the pH-responsive biodegradable CNPBA-Dex-b-PLA can efficiently load and deliver DOX into tumor cells and enhance the inhibition of cellular proliferation in vitro, providing a favorable platform as a drug delivery system for cancer therapy.

Monodisperse boronate polymeric particles synthesized by a precipitation polymerization strategy: particle formation and glycoprotein response from the standpoint of the Flory-Huggins model

The development of a highly specific recognition system for glycoprotein capture from complex biological samples is a prerequisite to the success of mass spectra-based glycoproteomics analysis. To achieve this purpose, a one-pot precipitation polymerization (PP) strategy with a novel solvent system composed of water/ethanol (4:1, v/v) is described for preparing boronate-affinity polymeric micro/nano particles using 4-vinylphenylboronic acid (VPBA) as the functional monomer and N,N'-methylenebis(acrylamide) (MBA) alone or together with divinylbenzene (DVB) as the cross-linker(s). The proposed polymerization strategy not only affords monodisperse polymeric submicrometer particles with a smooth surface and controllable size, ranging from 300 to 700 nm, but also increases the loading capacity of boronic acid, which could hardly be achieved by other polymerization methods, thus leading to the specific recognition of glycoproteins. The effects of solvent systems and monomers on the morphology and boronate-affinity capacity of prepared materials were further investigated based on the Flory-Huggins model. It was proved that the reaction rate of various monomers during particle formation might be the key factor affecting the affinity capacity for glycoproteins. Our results demonstrated that under the theoretical guidance of the Flory-Huggins model the PP strategy with a selected monomer and solvent system might provide a good approach to prepare submicrometer polymer particles with plenty of boronic acid groups on the surface to achieve a highly selective enrichment of glycoproteins.

Phenylboronic acid-functionalized polymeric micelles with a HepG2 cell targetability

Phenylboronic acid-functionalized amphiphilic block copolymer Pluronic-PMCC-BA was synthesized via ring-opening polymerization of 5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one (MBC) with fumaric acid as a catalyst followed by the deprotection of carboxyl groups by catalyzed hydrogenation and the condensation of 3-aminophenylboronic acid with the copolymer side groups. Pluronic-PMCC-BA can form stable micelle solution by self-assembly in water. The phenylboronic acid groups are located at the shell of micelle as proved by (1)H NMR. The diameter of drug-free micelles is approximate 60 nm. Nano-spheres with narrow size distribution could be observed in the TEM image. MTT assay results show that Pluronic-PMCC-BA exhibits slight cytotoxicity when the polymer concentration is higher than 25 μg mL(-1). The toxicities of DOX@Pluronic-PMCC and DOX@Pluronic-PMCC-BA to COS7, HeLa, and HepG2 cell lines are similar with those of free DOX. Interestingly, phenylboronic acid groups located at the surface of Pluronic-PMCC-BA micelles can recognize HepG2 cells and promote the drug uptake of the cells, which are observed by confocal laser scanning microscopy (CLSM). The results imply that Pluronic-PMCC-BA would be a promising material for targeted drug delivery to the cancer cells.

Boronate-dextran: an acid-responsive biodegradable polymer for drug delivery

Stimuli-responsive drug carriers have great potential to deliver bioactive materials on demand and to a specific location within the human body. Acid-responsive drug carriers can specifically release their payload in the acidic microenvironments of tumors or in the endosomal or lysosomal compartments within a cell. Here we describe an approach to functionalize vicinal diols of dextran with hydrophobic boronate esters in order to produce a water insoluble boronate dextran polymer (B-Dex), which spontaneously forms acid-responsive nanoparticles in water. We show the encapsulation of a hydrophobic anticancer drug doxorubicin into the particles. Hydrolysis of the boronate esters under mild acidic conditions recovers the hydrophilic hydroxyl groups of the dextran and disrupts the particles into water soluble fragments thereby leading to a pH-responsive release of the drug. According to dynamic light scattering (DLS) and UV/Vis spectroscopy, mild acidic conditions (pH 5.0) lead to a three-fold increase in the degradation of the particles and a four-fold increase in the release of the drug compared to the behavior of particles at pH 7.4. In vitro tests in Hela cells show no toxicity of the empty B-Dex nanoparticles, while the toxicity of doxorubicin-loaded B-Dex nanoparticles is comparable to that of the doxorubicin · HCl drug. Confocal fluorescence microscopy reveals that 100% of the Hela cells uptake doxorubicin-loaded B-Dex nanoparticles with a preferential accumulation of the nanoparticles in the cytoplasm.

Doxorubicin delivery to 3D multicellular spheroids and tumors based on boronic acid-rich chitosan nanoparticles

Boronic acid-rich chitosan-poly(N-3-acrylamidophenylboronic acid) nanoparticles (CS-PAPBA NPs) with the tunable size were successfully prepared by polymerizing N-3-acrylamidophenylboronic acid in the presence of chitosan in an aqueous solution. The CS-PAPBA NPs were then functionalized by a tumor-penetrating peptide iRGD and loading doxorubicin (DOX). The interaction between boronic acid groups of hydrophobic PAPBA and the amino groups of hydrophilic chitosan inside the nanoparticles was examined by solid-state NMR measurement. The size and morphology of nanoparticles were characterized by dynamic light scattering and electron microscopy. The cellular uptake, tumor penetration, biodistribution and antitumor activity of the nanoparticles were evaluated by using three-dimensional (3-D) multicellular spheroids (MCs) as the in vitro model and H22 tumor-bearing mice as the in vivo model. It was found that the iRGD-conjugated nanoparticles significantly improved the efficiency of DOX penetration in MCs, compared with free DOX and non-conjugated nanoparticles, resulting in the efficient cell killing in the MCs. In vivo antitumor activity examination indicated that iRGD-conjugated CS-PAPBA nanoparticles promoted the accumulation of nanoparticles in tumor tissue and enhanced their penetration in tumor areas, both of which improved the efficiency of DOX-loaded nanoparticles in restraining tumor growth and prolonging the life time of H22 tumor-bearing mice.

Phenylboronic-acid-modified amphiphilic polyether as a neutral gene vector

A phenylboronic-acid-modified amphiphilic block polyether is prepared via reaction of polyglycidol-block-poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide)-block-polyglycidol (Pluronic-PG) with 2-(N,N-dimethylaminomethyl)-5-aminomethyl phenylboronic acid using phosgene as a coupling reagent. The boronic-acid-modified non-cationic polymer binds plasmid pGL3 effectively, forms sub-µm polymer/DNA complex particles, and greatly facilitates the cell uptake of the plasmid. The efficiency of the polymer as a gene vector is evaluated in vitro by transfection of pGL3 to HeLa, COS-7 and HepG2 cells. Pluronic-PG-BA enhances the transfection efficiency by 100 to 1000 times compared with Pluronic-PG. The presence of serum does not significantly affect the transfection efficiency.

Conjugation of paclitaxel to iron oxide nanoparticles for tumor imaging and therapy

A strategy for conjugating an antitumor agent to superparamagnetic iron oxide nanoparticles (SPIONs) via a biocleavable ester binding is reported. Paclitaxel (PTX) was selected as a model drug. Both the in vitro and in vivo performance of the conjugates of SPION-PTX was investigated respectively. PTX can be released slowly through the hydrolysis of the ester bond in a pH-dependent manner and the SPION-PTX has near equal cytotoxity to the clinical PTX injection (Taxol) at the equivalent dose of PTX. Furthermore, the SPION-PTX can accumulate in tumor tissues as demonstrated by MRI and exhibit better tumor suppression effect than Taxol in vivo. The above good performance of the SPION-PTX together with the good biocompatibility of the SPIONs would promote greatly the application of the SPIONs in the biomedicine field.