Oxygen-Tolerant RAFT Polymerization Catalyzed by a Recyclable Biomimetic Mineralization Enhanced Biological Cascade System

An enzyme cascade system including glucose oxidase (GOx) and iron porphyrin (DhHP-6) is encapsulated in a metal-organic framework called zeolitic imidazolate framework-8 (ZIF-8) through one-step facile synthesis. The composite (GOx&DhHP-6@ZIF-8) is then used to initiate oxygen-tolerant reversible addition-fragmentation chain-transfer polymerization for different methacrylate monomers, such as 2-diethylaminoethyl methacrylate, 2-hydroxyethyl methacrylate, and poly(ethylene glycol) methyl ether methacrylate (M_n = 500 g mol^-1 ). The composite shows the robustness toward solvent and temperatures, all polymerizations using above monomers and catalyzing by GOx&DhHP-6@ZIF-8 exhibits high monomer conversion (>85%) and narrow molar mass dispersity (<1.3). Besides, acrylic and acrylamide monomers such as 2-hydroxyethyl acrylate and N,N-dimethylacrylamide are also carried to demonstrate the broad applicability. Proton nuclear magnetic resonance characterization and chain extension experiments confirm the retaining end groups of the resultant polymers, which is a significant feature of living polymerization. More importantly, the process of recycling the composite through a centrifuge is simplistic, and the composite still maintains similar activity compared to the original composites after five times. This low-cost and easily separated composite catalyst represents a versatile strategy to synthesize well-defined functional polymers suitable for industrial-scale production.

Förster Resonance Energy Transfer from Carbon Nanoparticles to a DNA-Bound Compound: A Method to Detect the Nature of Binding

A drug molecule can bind in various orientations to a DNA strand. Nature of the binding decides the functionality and efficacy of the drug. To innovate a new method to detect the nature of binding of a drug to DNA strands, herein we have used the dipole-dipole interaction driven Förster resonance energy transfer (FRET) between carbon nanoparticles (CNPs) and a DNA-bound small molecule, (E)-3-ethyl-2-(4-(pyrrolidin-1-yl)styryl)benzo[d]thiazol-3-ium (EPSBT), which belongs to the hemicyanine family and binds typically to the minor groove of a DNA duplex. EPSBT was designed to obtain appreciable fluorescence quantum yield, which constructed an efficient FRET pair with the synthesized CNPs. The tested compound prefers the thymine nucleobase to bind to the DNA strand. Orientation of its dipole on attachment to the DNA strand and the donor-acceptor distance dictate the FRET efficiency with the CNPs. The results provided a precise estimation of the nature of binding of EPSBT to the DNA backbone and, hence, supposedly will help in deciding the functional efficacy.

Supramolecular Nanoplatform Based on Mesoporous Silica Nanocarriers and Pillararene Nanogates for Fungus Control

Synthetic fungicides have been widely used to protect crops from fungal diseases. However, excessive use of synthetic fungicides leads to the generation of fungicide resistance in fungal pathogens. Recently, smart cargo delivery systems have been introduced for the construction of a pesticide delivery nanoplatform, benefiting from their controlled release performance. Herein, a fungal pathogen microenvironment-responsive supramolecular fungicide nanoplatform has been designed and constructed, using quaternary ammonium salt (Q)-modified mesoporous silica nanoparticles (MSN-Q NPs) as nanocarriers loaded with berberine hydrochloride (BH) and carboxylatopillar[5]arene (CP[5]A) as nanogates to form BH-loaded CP[5]A@MSN-Q NPs for effective inhibition of Botrytis cinerea. CP[5]A as nanogates can endow the fungicide nanoplatform with pH stimuli-responsive release features for the control of fungicide release. The loaded BH, as a natural plant fungicide, provides an ecofriendly alternative to synthetic fungicides for controlling B. cinerea. Interestingly, we use oxalic acid (OA) secreted by B. cinerea as a trigger so that BH can be released from the fungicide nanoplatform on demand under pathogen microenvironments for controlling B. cinerea. The experimental results indicate that the fabricated fungicide nanoplatform could effectively inhibit the mycelial growth and spore germination, providing a new way for the management of B. cinerea in actual application.

Polyphenol-Containing Nanoparticles: Synthesis, Properties, and Therapeutic Delivery

Polyphenols, the phenolic hydroxyl group-containing organic molecules, are widely found in natural plants and have shown beneficial effects on human health. Recently, polyphenol-containing nanoparticles have attracted extensive research attention due to their antioxidation property, anticancer activity, and universal adherent affinity, and thus have shown great promise in the preparation, stabilization, and modification of multifunctional nanoassemblies for bioimaging, therapeutic delivery, and other biomedical applications. Additionally, the metal-polyphenol networks, formed by the coordination interactions between polyphenols and metal ions, have been used to prepare an important class of polyphenol-containing nanoparticles for surface modification, bioimaging, drug delivery, and disease treatments. By focusing on the interactions between polyphenols and different materials (e.g., metal ions, inorganic materials, polymers, proteins, and nucleic acids), a comprehensive review on the synthesis and properties of the polyphenol-containing nanoparticles is provided. Moreover, the remarkable versatility of polyphenol-containing nanoparticles in different biomedical applications, including biodetection, multimodal bioimaging, protein and gene delivery, bone repair, antibiosis, and cancer theranostics is also demonstrated. Finally, the challenges faced by future research regarding the polyphenol-containing nanoparticles are discussed.

An l-cystine/l-cysteine impregnated nanofiltration membrane with the superior performance of an anchoring heavy metal in wastewater

Considerable efforts are being made to develop new materials and technologies for the efficient and fast removal of toxic ions in drinking water. In this work, we developed a sulfur-complexed strategy to enhance the removal capability of heavy metal ions using the polyamide nanofiltration membrane by the covalent anchoring of l-cystine and l-cysteine. The sulfur-functionalized polyamide nanofiltration membrane exhibits superior complexation of heavy metal ions and can efficiently remove them from high-concentration wastewater. As a result, the sulfur-functionalized nanofiltration membrane not only showed excellent desalination performance but also achieved a record removal rate of heavy metal ions (99.99%), which can effectively reduce Hg(ii) concentration from 10 ppm to an extremely low level of 0.18 ppb, well below the acceptable limits in drinking water (2 ppb). Moreover, the sulfur-functionalized nanofiltration membrane showed an exciting long-term stability and can be easily regenerated without significant loss of Hg(ii) removal efficiency even after six cycles. Such outstanding performances were attributed to the synthetic effect of Hg-S coordinative interaction, electrostatic repulsion, and the sieving action of nanopores. These results highlight the tremendous potential of thiol/disulfide-functionalized NF active layer as an appealing platform for removing heavy metal ions from polluted water with high performance in environmental remediation.

Glutathione-adaptive peptide amphiphile vesicles rationally designed using positionable disulfide-bridges for effective drug transport

The drug loading/releasing capability of GSH-responsive nanovesicles self-assembled from peptide amphiphiles was controlled by varying the location and number of disulfide-linkages in the peptide for the selective drug-release into tumor cells.

Mesoporous silica-coated bismuth nanohybrids as a new platform for photoacoustic/computed tomography imaging and synergistic chemophotothermal therapy

AIM

Polyethylene glycol modified mesoporous silica-coated bismuth nanohybrids (Bi@mSiO₂-PEG) are fabricated for chemothermotherapy and multimodal imaging.

MATERIALS & METHODS

The Bi@mSiO₂-PEG are synthesized by coating mesoporous SiO₂ onto metallic Bi cores, followed by PEG modification. Their cytotoxicity, photothermal effect, drug loading, antitumor effect and imaging abilities are evaluated.

RESULTS

The nanohybrids show good biocompatibility, strong near-infrared absorbance, high photothermal conversion efficiency (∼36.6%), prominent infrared thermal imaging and photothermal killing efficacy on cancer cells. Utilizing the nanohybrids as potent drug carriers, a synergistic antitumor effect through chemothermotherapy is realized. Thanks to the superhigh x-ray attenuation coefficient and strong photothermal ability, high-contrast photoacoustic and x-ray computed tomography imaging are achieved.

CONCLUSION

These results reveal great potentials of the Bi@mSiO₂-PEG for precise and efficient anticancer treatments.

Magnetic Mesoporous Silica Gated with Doped Carbon Dot for Site-Specific Drug Delivery, Fluorescence, and MR Imaging

Construction of a theranostic agent which integrates multiple modalities with different functions into one entity is challenging from a molecular design and synthesis perspective. In this context, the present paper reports the fabrication of a novel type of multifunctional hybrid nanoparticle composed of magnetic gadolinium oxide-iron oxide core, mesoporous silica shell gated with boronic acid functionalized highly luminescent carbon quantum dot (BNSCQD). The porous silica shell acts as an excellent reservoir for anticancer drug 5-fluorouracil, whereas the BNSCQD cap impressively controls the drug transport under simulated intracellular environment. Furthermore, recognition and fluorescence turn on response of BNSCQD toward cell surface glycan sialyl Lewis^a (SL^a) enables targeted drug release and excellent fluorescence imaging of SL^a overexpressed HePG2 cancer cells. The r₁ and r₂ relaxivities of the material are found to be 10 and 165 mM^-1 s^-1 which is comparable to commercially available magnetic resonance imaging contrast agents. Benefiting from the combined advantages of dual stimuli-responsive drug release, excellent optical imaging, and MR imaging, this novel construct can be a promising theranostic material.

A Metal-Polyphenol Network Coated Nanotheranostic System for Metastatic Tumor Treatments

As a characteristic trait of most tumor types, metastasis is the major cause of the death of patients. In this study, a photothermal agent based on gold nanorod is coated with metal (Gd³⁺ )-organic (polyphenol) network to realize combination therapy for metastatic tumors. This nanotheranostic system significantly enhances antitumor therapeutic effects in vitro and in vivo with the combination of photothermal therapy (PTT) and chemotherapy, also can remarkably prevent the invasion and metastasis due to the presence of polyphenol. After the treatment, an 81% decrease in primary tumor volumes and a 58% decrease in lung metastasis are observed. In addition, the good performance in magnetic resonance imaging, computerized tomography, and photothermal imaging of the nanotheranostic system can realize image-guided therapy. The multifunctional nanotheranostic system will find a great potential in diagnosis and treatment integration in tumor treatments, and broaden the applications of PTT treatment.

Development of Sphere-Polymer Brush Hierarchical Nanostructure Substrates for Fabricating Microarrays with High Performance

In this work, a sphere-polymer brush hierarchical nanostructure-modified glass slide has been developed for fabricating high-performance microarrays. The substrate consists of a uniform 160 nm silica particle-self-assembled monolayer on a glass slide with a postcoated poly(glycidyl methacrylate) (PGMA) brush layer (termed PGMA@3D(160) substrate), which can provide three-dimensional (3D) polymer brushes containing abundant epoxy groups for directly immobilizing various biomolecules. As a typical example, the interactions of three monosaccharides (4-aminophenyl β-d-galactopyranoside, 4-aminophenyl β-d-glucopyranoside, and 4-aminophenyl α-d-mannopyranoside) with two lectins (biotinylated ricinus communis agglutinin 120 and biotinylated concanavalin A from Canavalia ensiformis) have been assessed by PGMA@3D(160) substrate-based carbohydrate microarrays. The carbohydrate microarrays show good selectivity, strong multivalent interaction, and low limit of detection (LOD) in the picomolar range without any signal amplification. Furthermore, the proposed sphere-polymer brush hierarchical nanostructure substrates can be easily extended to fabricate other types of microarrays for DNA and protein detection. PGMA@3D(160) substrate-based microarrays exhibit higher reaction efficiencies and lower LODs (by at least 1 order of magnitude) in comparison to those of two-dimensional microarrays, which are fabricated on planar epoxy substrates, making it a promising platform for bioanalytical and biomedical applications.

Templated Polymer Replica Nanoparticles to Facilitate Assessment of Material-Dependent Pharmacokinetics and Biodistribution

Surface modification is frequently used to tailor the interactions of nanoparticles with biological systems. In many cases, the chemical nature of the treatments employed to modify the biological interface (for example attachment of hydrophilic polymers or targeting groups) is the focus of attention. However, isolation of the fundamental effects of the materials employed to modify the interface are often confounded by secondary effects imparted by the underlying substrate. Herein, we demonstrate that polymer replica particles templated from degradable mesoporous silica provide a facile means to evaluate the impact of surface modification on the biological interactions of nanomaterials, independent of the substrate. Poly(ethylene glycol) (PEG), poly(N-(2 hydroxypropyl)methacrylamide) (PHPMA), and poly(methacrylic acid) (PMA) were templated onto mesoporous silica and cross-linked and the residual particles were removed. The resulting nanoparticles, comprising interfacial polymer alone, were then investigated using a range of in vitro and in vivo tests. As expected, the PEG particles showed the best stealth properties, and these trends were consistent in both in vitro and in vivo studies. PMA particles showed the highest cell association in cell lines in vitro and were rapidly taken up by monocytes in ex vivo whole blood, properties consistent with the very high in vivo clearance subsequently seen in rats. In contrast, PHPMA particles showed rapid association with both granulocytes and monocytes in ex vivo whole blood, even though in vivo clearance was less rapid than the PMA particles. Rat studies confirmed better systemic exposure for PEG and PHPMA particles when compared to PMA particles. This study provides a new avenue for investigating material-dependent biological behaviors of polymer particles, irrespective of the properties of the underlying core, and provides insights for the selection of polymer particles for future biological applications.

Carbon Dot Based, Naphthalimide Coupled FRET Pair for Highly Selective Ratiometric Detection of Thioredoxin Reductase and Cancer Screening

The fluorescence resonance energy transfer (FRET) mechanism has been established between carbon dots (CDs) and naphthalimide to monitor the activity of thioredoxin reductase (TrxR), which is often overexpressed in many cancer cells. The naphthalimide moiety was covalently attached to the surface of CDs through a disulfide linkage. In normal cell conditions (when devoid of high concentrations of TrxR), the CDs act as an energy donor and naphthalimide acts as an acceptor, which establishes the FRET pair as interpreted from the emission at λ_em = 565 nm, when excited at λ_ex = 360 nm. However, contrary to this, the elevated levels of TrxR cause the breakage of disulfide bonds and consequently abolishes the FRET pair through the release of the naphthalimide moiety from the surface of CDs. This process was studied by monitoring of fluorescence intensity at λ_em = 565 and 440 nm, when excited at the same wavelength (λ_ex = 360 nm). The TrxR based ratiometric quenching and enhancement of fluorescence intensity offers an interesting opportunity to monitor the enzyme activities and has many advantages over conventional monitoring of fluorescence intensity at a single wavelength to avoid interference of external factors. Fluorescence images of cancer cells in response to the nanosensor were visualized under a confocal microscope. Cytotoxicity study of nanosensor retards the growth of HeLa and MCF-7 cell lines in the presence of visible light. Therefore, the nanosensor also acts as a theranostic agent to diagnose as well as killing of cancer cells.

pH and Thermal Dual-Responsive Nanoparticles for Controlled Drug Delivery with High Loading Content

A pH and thermal dual-responsive nanocarrier with silica as the core and block copolymer composed of poly(methacrylic acid) (PMAA) and poly(N-isopropylacrylamide) (PNIPAM) as the shell was prepared by surface-initiated reversible addition-fragmentation chain-transfer (SI-RAFT) polymerization. The resulting SiO2-PMAA-b-PNIPAM particles dispersed individually in an aqueous solution at a high pH and a low temperature but reversibly agglomerated under acidic conditions or at elevated temperatures. These dual-responsive nanoparticles were used as carriers to deliver the model drug doxorubicin (DOX) with unusually high entrapment efficiency and loading content, which is due to the small size (15 nm), light weight of the cores, and high graft density (0.619 chains/nm2) achieved by SI-RAFT polymerization. The release rate was controlled by both the pH and temperature of the surrounding medium. Moreover, these particles selectively precipitated at acidic conditions with increased temperature, which may enhance their ability to accumulate at tumor sites. Cytotoxicity studies demonstrated that DOX-loaded nanoparticles are highly active against Hela cells and more effective than free DOX of an equivalent dose. A cellular uptake study revealed that SiO2-PMAA-b-PNIPAM nanoparticles could successfully deliver DOX molecules into the nuclei of Hela cells. All these features indicated that SiO2-PMAA-b-PNIPAM nanoparticles are a promising candidate for therapeutic applications.

Fluorescein isothiocyanate-dyed mesoporous silica nanoparticles for tracking antioxidant delivery

This study investigated the cellular uptake of fluorescein isothiocyanate-labelled mesoporous silica nanoparticles (FITC-MSNs), amine-functionalised FITC-MSNs (AP-FITC-MSNs) and their gallic acid (GA)-loaded counterparts. Mesoporous silica nanoparticles were labelled with fluorescein isothiocyanate, functionalised by 3-aminopropyltriethoxysilane (APTES) (AP-FITC-MSNs) and then loaded by GA. All nanoparticles were characterised by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, and X-ray diffraction. The cytotoxicity of different concentrations of dyed nanoparticles was investigated using (3-(4,5-trihydroxybenzoic acid, dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and flow cytometry. TEM images showed that the average particle sizes of FITC-MSNs and AP-FITC-MSNs were about 100 and 110 nm, respectively. These nanoparticles were internalised by Caco-2 cells, accumulated and dispersed into the cytoplasm, nucleus, and subcellular organelles. Nanoparticles containing GA clearly decreased the viability of cells. FITC-MSNs showed no toxicity on Caco-2 cells at concentrations of ≤50 µg/ml. Functionalisation of FITC-MSNs using APTES decreased toxicity effects on the cells. It was found that FITC-MSNs can be applied at low concentrations as a marker in the cells. In addition, AP-FITC-MSNs showed better biocompatibility with Caco-2 cells than FITC-MSNs, because of their positive surface charges.

Surface-Initiated Controlled Radical Polymerization: State-of-the-Art, Opportunities, and Challenges in Surface and Interface Engineering with Polymer Brushes

The generation of polymer brushes by surface-initiated controlled radical polymerization (SI-CRP) techniques has become a powerful approach to tailor the chemical and physical properties of interfaces and has given rise to great advances in surface and interface engineering. Polymer brushes are defined as thin polymer films in which the individual polymer chains are tethered by one chain end to a solid interface. Significant advances have been made over the past years in the field of polymer brushes. This includes novel developments in SI-CRP, as well as the emergence of novel applications such as catalysis, electronics, nanomaterial synthesis and biosensing. Additionally, polymer brushes prepared via SI-CRP have been utilized to modify the surface of novel substrates such as natural fibers, polymer nanofibers, mesoporous materials, graphene, viruses and protein nanoparticles. The last years have also seen exciting advances in the chemical and physical characterization of polymer brushes, as well as an ever increasing set of computational and simulation tools that allow understanding and predictions of these surface-grafted polymer architectures. The aim of this contribution is to provide a comprehensive review that critically assesses recent advances in the field and highlights the opportunities and challenges for future work.

Synthesis of well-defined epoxy-functional spherical nanoparticles by RAFT aqueous emulsion polymerization

The environmentally-friendly synthesis of epoxy-functional spherical nanoparticles is achieved via RAFT aqueous emulsion polymerization of glycidyl methacrylate under mild conditions; derivatization of such nanoparticles with sodium azide or diamines is demonstrated.

Stimuli-responsive delivery vehicles based on mesoporous silica nanoparticles: recent advances and challenges

In the past decade, stimuli-responsive drug delivery vehicles based on surface-functionalized mesoporous silica nanoparticles have attracted intense interest as a new type of drug carrier.

Surface Immobilization of pH-Responsive Polymer Brushes on Mesoporous Silica Nanoparticles by Enzyme Mimetic Catalytic ATRP for Controlled Cargo Release

Peroxidase mimetic catalytic atom transfer radical polymerization (ATRP) was first used to install tertiary amine-functionalized polymer brushes on the surface of mesoporous silica nanoparticles (MSNs) in a facile and highly efficient manner. Poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) brushes-grafted MSNs were fabricated by biocompatible deuterohemin-β-Ala-His-Thr-Val-Glu-Lys (DhHP-6)-catalyzed surface-initiated ATRP (SI-ATRP). The resulting organic⁻inorganic hybrid nanocarriers were fully characterized by Fourier transform-infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), SEM, TEM, Elemental analysis, Zeta-potential, and N₂ adsorption⁻desorption isotherms, which demonstrated the successful coating of pH-responsive polymers on the MSN surface. Rhodamine 6G (Rh6G) dyes were further loaded within the mesopores of this nanocarrier, and the release of Rh6G out of MSNs in a controlled fashion was achieved upon lowing the solution pH. The electrostatic repulsion of positively-charged tertiary ammonium of PDMAEMAs in acidic environments induced the stretching out of polymer brushes on MSN surfaces, thus opening the gates to allow cargo diffusion out of the mesopores of MSNs.

Taste masking of a drug by pH-responsive coordination polymer-coated mesoporous silica nanoparticles

We developed a simple and efficient method for fabricating a taste-masked oral drug delivery system (DDS) that regulates the release of unpleasant drug taste via the change in pH value in the physiological environment of the alimentary canal.

Acid and base dual-controlled cargo molecule release from polyaniline gated-hollow mesoporous silica nanoparticles

Polyaniline chains grafted onto the surface of hollow mesoporous silica served as the gate to realize drug dual-controlled release.

Smart mesoporous silica nanoparticles gated by pillararene-modified gold nanoparticles for on-demand cargo release

A new drug delivery system, based on mesoporous silica nanoparticles gated by carboxylatopillar[5]arene-modified gold nanoparticles, has been fabricated for controlled drug release.