Mesoporous Silica-Templated Assembly of Luminescent Polyester Particles

We report the template assembly of luminescent poly-3-hydroxybutyrate (PHB) particles doped with rare-earth complexes. The hydrophobic polymer, PHB, has been infiltrated into the nanopores of mesoporous silica (MS) particles in organic solvent. Because of the van der Waals interaction of the polymer chains, PHB loaded in the nanopores yields replicated particles following removal of the MS template. To prevent aggregation of the hydrophobic PHB particles in aqueous media, the PHB-loaded mesoporous silica particles were coated with a polyelectrolyte multilayer (PEM) shell through the layer-by-layer (LbL) assembly of poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS). Following removal of the silica core, the PEM-coated PHB replicas were used to effectively coordinate rare-earth complexes (europium β-diketone, EuC). The EuC-loaded PHB replicas coated with PAH/PSS emit intense luminescence over a wide pH range (3−11) and for at least several months in aqueous solution, which is due to the intramolecular energy transfer from the ligand to the luminescent center in the rare-earth complexes. The PHB replicas, with stable and intense luminescence, may find application in diagnostics and drug delivery

Dual-Stimuli-Responsive Polypeptide Nanoparticles for Photothermal and Photodynamic Therapy

We report the assembly of dual-responsive polypeptide nanoparticles loaded with indocyanine green (ICG) using a mesoporous silica (MS) templating method for photothermal and photodynamic therapy. Polypeptide nanoparticles composed of thiol-modified polylysine (PLL) are cross-linked with disulfide bonds and modified with poly­(ethylene glycol) (PEG) and pH-sheddable dimethylmaleic anhydride (DMMA), which exhibit reduction- and pH-responsiveness. Cross-linking with disulfide bonds does not influence the free amine groups on PLL chains for further cargo conjugation and surface modification. The stripped DMMA at acidic pH reverses the zeta potential of PLL nanoparticles from negative to positive charge and subsequently results in high cell association. The thermo-responsiveness and singlet oxygen generation of the loaded ICG in DMMA-modified PLL nanoparticles are comparable to those of free ICG under laser irradiation, which induces higher cytotoxicity to cancer cells compared to succinic anhydride (SA)-modified PLL nanoparticles that are not pH-responsive. The reported dual-responsive PLL nanoparticles provide a promising platform for improved photothermal and photodynamic therapy

Tuning the Mechanical Properties of Nanoporous Hydrogel Particles via Polymer Cross-Linking

Soft hydrogel particles with tunable mechanical properties are promising for next-generation therapeutic applications. This is due to the increasingly proven role that physicochemical properties play in particulate-based delivery vectors, both <i>in vitro</i> and <i>in vivo</i>. The ability to understand and quantify the mechanical properties of such systems is therefore essential to optimize function and performance. We report control over the mechanical properties of poly­(methacrylic acid) (PMA) hydrogel particles based on a mesoporous silica templating method. The mechanical properties of the obtained particles can be finely tuned through variation of the cross-linker concentration, which is hereby quantified using a cross-linking polymer with a fluorescent tag. We demonstrate that the mechanical properties of the particles can be elucidated using an atomic force microscopy (AFM) force spectroscopy method, which additionally allows for the study of hydrogel material properties at the nanoscale through high-resolution force mapping. Young’s modulus and stiffness of the particles were tuned between 0.04 and 2.53 MPa and between 1.6 and 28.4 mN m^–1, respectively, through control over the cross-linker concentration. The relationship between the concentration of the cross-linker added and the amount of adsorbed polymer was observed to follow a Langmuir isotherm, and this relationship was found to correlate linearly with the particle mechanical properties

Dynamic Flow Impacts Cell–Particle Interactions: Sedimentation and Particle Shape Effects

The interaction of engineered particles with biological systems determines their performance in biomedical applications. Although standard static cell cultures remain the norm for in vitro studies, modern models mimicking aspects of the dynamic in vivo environment have been developed. Herein, we investigate fundamental cell–particle interactions under dynamic flow conditions using a simple and self-contained device together with standard multiwell cell culture plates. We engineer two particle systems and evaluate their cell interactions under dynamic flow, and we compare the results to standard static cell cultures. We find substantial differences between static and dynamic flow conditions and attribute these to particle shape and sedimentation effects. These results demonstrate how standard static assays can be complemented by dynamic flow assays for a more comprehensive understanding of fundamental cell–particle interactions

Surfactant-Modified Ultrafine Gold Nanoparticles with Magnetic Responsiveness for Reversible Convergence and Release of Biomacromolecules

It is difficult to synthesize magnetic gold nanoparticles (AuNPs) with ultrafine sizes (<2 nm) based on a conventional method via coating AuNPs using magnetic particles, compounds, or ions. Here, magnetic cationic surfactants C₁₆H₃₃N⁺(CH₃)₃[CeCl₃Br]⁻ (CTACe) and C₁₆H₃₃N⁺(CH₃)₃[GdCl₃Br]⁻ (CTAGd) are prepared by a one-step coordination reaction, i.e., C₁₆H₃₃N⁺(CH₃)₃Br^– (CTABr) + CeCl₃ or GdCl₃ → CTACe or CTAGd. A simple strategy for fabricate ultrafine (<2 nm) magnetic gold nanoparticles (AuNPs) via surface modification with weak oxidizing paramagnetic cationic surfactants, CTACe or CTAGd, is developed. The resulting AuNPs can highly concentrate the charges of cationic surfactants on their surfaces, thereby presenting strong electrostatic interaction with negatively charged biomacromolecules, DNA, and proteins. As a consequence, they can converge DNA and proteins over 90% at a lower dosage than magnetic surfactants or existing magnetic AuNPs. The surface modification with these cationic surfactants endows AuNPs with strong magnetism, which allows them to magnetize and migrate the attached biomacromolecules with a much higher efficiency. The native conformation of DNA and proteins can be protected during the migration. Besides, the captured DNA and proteins could be released after adding sufficient inorganic salts such as at <i>c</i>_NaBr = 50 mmol·L^–1. Our results could offer new guidance for a diverse range of systems including gene delivery, DNA transfection, and protein delivery and separation

Interface Assembly of Polymer Networks on Metal–Organic Frameworks for the Engineering of Functional Nanoparticles

We report a versatile approach for the engineering of functional polymer nanoparticles (NPs) with tunable sizes, stiffness, and responsiveness via templating zeolitic imidazolate framework-8 (ZIF-8) NPs. This method is applicable to various components ranging from synthetic polymers to biomacromolecules, which are preloaded in ZIF-8 NPs and simultaneously cross-linked during the removal of the templates under mild conditions. Different cross-linking strategies (i.e., thiol-disulfide exchange, click chemistry, amidation reaction, and Schiff base reaction) are feasible for the formation of polymer networks. The advantages of the reported method rely on the simple assembly process, versatility of polymer components, and good control over physicochemical properties of polymer NPs. The versatile assembly strategy together with the tunable functions makes the polymer NPs promising for therapeutic delivery

Porous Waterborne Polyurethane Films Templated from Pickering Foams for Fabrication of Synthetic Leather

Waterborne polyurethane (WPU) latex nanoparticles with proven interfacial activity were utilized to stabilize air–water interfaces of Pickering foams through interfacial interaction with hydrophobic fumed silica particles (SPs). The rheological properties of the Pickering foam were tailored through adjustment of their SP content, which influenced their formability and stability. A Pickering foam stabilized with WPU and SPs was used as a template to prepare a WPU–SP composite porous film. The as-prepared film had intact open-cell porous structures, which increased its water absorption and water-vapor permeability. The porous film was used as a middle layer in the preparation of synthetic leather via a four-step “drying method”. Compared with commercial synthetic leather, the lab-made synthetic leather with a middle layer made of the WPU–SP composite porous film exhibited a richer porous structure, acceptable wetting on a fabric substrate, a thicker porous layer, and higher water-vapor permeability. This work provides a novel and facile approach for preparing WPU–SP Pickering foams. Furthermore, the foams have the potential to function as a sustainable material for creating a porous-structured synthetic leather made from WPU, which may be utilized as an alternative to solvent-based synthetic leather

DataSheet1_Facile Synthesis of Water-Soluble Rhodamine-Based Polymeric Chemosensors via Schiff Base Reaction for Fe3+ Detection and Living Cell Imaging.docx

Quantitative and accurate determination of iron ions play a vital role in maintaining environment and human health, but very few polymeric chemosensors were available for the detection of Fe3+ in aqueous solutions. Herein, a water-soluble rhodamine-poly (ethylene glycol) conjugate (DRF-PEG), as a dual responsive colorimetric and fluorescent polymeric sensor for Fe3+ detection with high biocompatibility, was first synthesized through Schiff base reaction between rhodamine 6G hydrazide and benzaldehyde-functionalized polyethylene glycol. As expected, the introduction of PEG segment in DRF-PEG significantly improved the water solubility of rhodamine derivatives and resulted in a good biosensing performance. The detection limit of DRF-PEG for Fe3+ in pure water is 1.00 μM as a fluorescent sensor and 3.16 μM as a colorimetric sensor at pH 6.5. The specific sensing mechanism of DRF-PEG toward Fe3+ is proposed based on the intramolecular charge transfer (ICT) mechanism, in which the O and N atoms in rhodamine moiety, together with the benzene groups from benzaldehyde-modified PEG segment, participate in coordination with Fe3+. Furthermore, DRF-PEG was applied for the ratiometric imaging of Fe3+ in HeLa cells and showed the potential for quantitative determination of Fe3+ in fetal bovine serum samples. This work provides insights for the design of water-soluble chemosensors, which can be implemented in iron-related biological sensing and clinical diagnosis.</p

Surface-Initiated Polymerization within Mesoporous Silica Spheres for the Modular Design of Charge-Neutral Polymer Particles

We report a templating approach for the preparation of functional polymer replica particles via surface-initiated polymerization in mesoporous silica templates. Subsequent removal of the template resulted in discrete polymer particles. Furthermore, redox-responsive replica particles could be engineered to disassemble in a reducing environment. Particles, made of poly­(methacryloyloxyethyl phosphorylcholine) (PMPC) or poly­[oligo­(ethylene glycol) methyl ether methacrylate] (POEGMA), exhibited very low association to human cancer cells (below 5%), which renders the reported charge-neutral polymer particles a modular and versatile class of highly functional carriers with potential applications in drug delivery

Biomimetic Hemostatic Powder Derived from Coacervate-Immobilized Thermogelling Copolymers

Intrinsic hemostasis is an innate body response to prevent bleeding based on the sol–gel transition of blood. However, it is often inadequate for exceptional situations, such as acute injury and coagulation disorders, which typically require immediate medical intervention. Herein, we report the preparation of an efficient hemostatic powder, composed of tannic acid (TA), poly(ethylene glycol) (PEG), and poly(d,l-lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(d,l-lactide-co-glycolide) triblock copolymer (TB), for biomimetic hemostasis at the bleeding sites. TA has a high affinity for biomolecules and cells and can form coacervates with PEG driven by hydrogen bonding. TB enhances the mechanical strength and provides thermoresponsiveness. The hemostatic powder can rapidly transit into a physical and biodegradable seal on wet substrates under physiological conditions, demonstrating its promise for the generation of instant artificial clots. Importantly, this process is independent of the innate blood clotting process, which could benefit those with blood clotting disorders. This biomimetic hemostatic powder is an adaptive topical sealing agent for noncompressible and irregular wounds, which is promising for biomedical applications