Thermoresponsive Gels with Embedded Starch Microspheres for Optimized Antibacterial and Hemostatic Properties.

Apart from single hemostasis, antibacterial and other functionalities are also desirable for hemostatic materials to meet clinical needs. Cationic materials have attracted great interest for antibacterial/hemostatic applications, and it is still desirable to explore rational structure design to address the challenges in balanced hemostatic/antibacterial/biocompatible properties. In this work, a series of cationic microspheres (QMS) were prepared by the facile surface modification of microporous starch microspheres with a cationic tannic acid derivate, the coating contents of which were adopted for the first optimization of surface structure and property. Thermoresponsive gels with embedded QMS (F-QMS) were further prepared by mixing a neutral thermosensitive polymer and QMS for second structure/function optimization through different QMS and loading contents. In vitro and in vivo results confirmed that the coating content plays a crucial role in the hemostatic/antibacterial/biocompatible properties of QMS, but varied coating contents of QMS only lead to a classical imperfect performance of cationic materials. Inspiringly, the F-QMS-4 gel with an optimal loading content of QMS4 (with the highest coating content) achieved a superior balanced in vitro hemostatic/antibacterial/biocompatible properties, the mechanism of which was revealed as the second regulation of cell-material/protein-material interactions. Moreover, the optimal F-QMS-4 gel exhibited a high hemostatic performance in a femoral artery injury model accompanied by the easy on-demand removal for wound healing endowed by the thermoresponsive transformation. The present work offers a promising approach for the rational design and facile preparation of cationic materials with balanced hemostatic/antibacterial/biocompatible properties.

Rough Nanovaccines Boost Antitumor Immunity Through the Enhancement of Vaccination Cascade and Immunogenic Cell Death Induction.

Nanovaccines have attracted intense interests for efficient antigen delivery and tumor-specific immunity. It is challenging to develop a more efficient and personalized nanovaccine to maximize all steps of the vaccination cascade by exploiting the intrinsic properties of nanoparticles. Here, biodegradable nanohybrids (MP) composed of manganese oxide nanoparticles and cationic polymers are synthesized to load a model antigen ovalbumin to form MPO nanovaccines. More interestingly, MPO could serve as autologous nanovaccines for personalized tumor treatment taking advantage of in situ released tumor-associated antigens induced by immunogenic cell death (ICD). The intrinsic properties of MP nanohybrids including morphology, size, surface charge, chemical, and immunoregulatory functions are fully exploited to enhance of all steps of the cascade and induce ICD. MP nanohybrids are designed to efficiently encapsulate antigens by cationic polymers, drain to lymph nodes by appropriate size, be internalized by dendritic cells (DCs) by rough morphology, induce DC maturation through cGAS-STING pathway, and enhance lysosomal escape and antigen cross-presentation through the "proton sponge effect". The MPO nanovaccines are found to efficiently accumulate in lymph nodes and elicit robust specific T-cell immune responses to inhibit the occurrence of ovalbumin-expressing B16-OVA melanoma. Furthermore, MPO demonstrate great potential to serve as personalized cancer vaccines through the generation of autologous antigen depot through ICD induction, activation of potent antitumor immunity, and reversal of immunosuppression. This work provides a facile strategy for the construction of personalized nanovaccines by exploiting the intrinsic properties of nanohybrids.

Heparinized anticoagulant coatings based on polyphenol-amine inspired chemistry for blood-contacting catheters.

Blood-contacting catheters occupy a vital position in modern clinical treatment including but not limited to cardiovascular diseases, but catheter-related thrombosis associated with high morbidity and mortality remains a major health concern. Hence, there is an urgent need for functionalized catheter surfaces with superior hemocompatibility that prevent protein adsorption and thrombus formation. In this work, we developed a strategy for constructing a kind of polyphenol-amine coating on the TPU surface (TLA) with tannic acid and lysine via simple dip-coating, inspired by dopamine adhesion. Based on the long-term stability and modifiable properties of TLA coatings, heparin was introduced by an amide reaction to provide anticoagulant activity (TLH). X-ray photoelectron spectroscopy and surface zeta potential measurements fully indicated the successful immobilization of heparin. Water contact angle measurements demonstrated good hydrophilicity and stability for 15 days of TLH coatings. Furthermore, the TLH coatings exhibited significant hemocompatibility and no cytotoxicity. The good antithrombotic properties of the functionalized surfaces were confirmed by an ex vivo blood circulation model. The present work is supposed to find potential clinical applications for preventing surface-induced thrombosis of blood-contacting catheters.

Controlled Synthesis and Surface Engineering of Janus Chitosan-Gold Nanoparticles for Photoacoustic Imaging-Guided Synergistic Gene/Photothermal Therapy.

The unsymmetrical morphology and unique properties of Janus nanoparticles (JNPs) provide superior performances for biomedical applications. In this work, a general and facile strategy is developed to construct a series of symmetrical and unsymmetrical chitosan/gold nanoparticles. Taking advantage of the active motion derived from Janus structure, selective surface functionalization of polysaccharide domain, and photothermal effect of gold nanorods, Janus chitosan/gold nanoparticles (J-Au-CS) are selected as a model system to construct Janus-structured chitosan/gold nanohybrids (J-ACP). Near-infrared (NIR)-responsive J-ACP composed of polycationic chitosan nanospheres and PEGylated gold nanorods hold great potential to realize photoacoustic (PA) imaging-guided complementary photothermal therapy (PTT)/gene therapy for breast cancer. The morphology effect of chitosan/gold nanostructures on enhanced PTT, cellular uptake, and gene transfection is investigated. The feasibility of PA imaging to track the accumulation of J-ACP and guide PTT is also explored. Notably, synergistic therapy is achieved based on PTT-enhanced gene therapy. In addition, the loading function of chitosan/gold nanoparticles for fluorescence imaging is demonstrated. The current work extends the application of JNPs for imaging-guided synergistic cancer therapy and provides flexible candidates with distinct structures for diverse biomedical applications.

Biomass-Derived Multilayer-Structured Microparticles for Accelerated Hemostasis and Bone Repair.

It is very desirable to develop advanced sustainable biomedical materials with superior biosafety and bioactivity for clinical applications. Herein, biomass-derived multilayer-structured absorbable microparticles (MQ x T y ) composed of starches and plant polyphenols are readily constructed for the safe and effective treatment of bone defects with intractable bleeding by coating multiple layers of quaternized starch (Q+) and tannic acid onto microporous starch microparticles via facile layer-by-layer assembly. MQ x T y microparticles exhibit efficient degradability, low cytotoxicity, and good blood compatibility. Among various MQ x T y microparticles with distinct Q+/T- double layers, MQ2T2 with outmost polyphenol layer possess the unique properties of platelet adhesion/activation and red blood cell aggregation, resulting in the best hemostatic performance. In a mouse cancellous-bone-defect model, MQ2T2 exhibits the favorable hemostatic effect, low inflammation/immune responses, high biodegradability, and promoted bone repair. A proof-of-concept study of beagles further confirms the good performance of MQ2T2 in controlling intractable bleeding of bone defects. The present work demonstrates that such biomass-based multilayer-structured microparticles are very promising biomedical materials for clinical use.

Facile Surface Multi-Functionalization of Biomedical Catheters with Dual-Microcrystalline Broad-Spectrum Antibacterial Drugs and Antifouling Poly(ethylene glycol) for Effective Inhibition of Bacterial Infections.

With the development of biomedical materials, the widespread use of implantable medical devices such as biomedical catheters has saved lives and improved therapeutic outcomes in the clinic. Biomedical catheters (BCs) have the ability to connect the body inside and outside and are widely used in clinical sites for fluid discharging, blood indwelling, mechanical ventilating, and so on. However, catheter-related infections (CRIs) are common nosocomial infections with high morbidity and mortality. The pathogens in the urinary tract, blood, and lung tissue carried by BCs may be the direct cause of CRIs, and the bacterial biofilm on the surface of BCs provides a notable source of persistent diseases. Microcrystalline sulfamethoxazole (SMZ) and trimethoprim (TMP) were prepared in this study to increase both the specific surface area and water-solubility of antibacterial drugs, as well as to enhance the antibacterial and antifouling effects on the surface of BCs. As-prepared drugs and the excellent antifouling agent polyethylene glycol (PEG) were then used for the functionalization of BCs. The result indicated that the sizes of microcrystalline SMZ and TMP were 0.5-3 µm, 1-5 µm, respectively. The coating of BC-PEG-drugs exhibited excellent antibacterial efficacy in culture as well as preeminent antibacterial and antifouling abilities on the surface of BCs toward Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Moreover, the BC-PEG-drugs groups exhibited outstanding antibacterial and antifouling abilities in vivo by an animal infection model with S. aureus. This study offers a simple and effective approach for the synthesis of antibacterial and antifouling coatings that consist of microcrystalline drugs, with promising clinical applicability.

Flexible Cationic Nanoparticles with Photosensitizer Cores for Multifunctional Biomedical Applications.

One challenge for multimodal therapy is to develop appropriate multifunctional agents to meet the requirements of potential applications. Photodynamic therapy (PDT) is proven to be an effective way to treat cancers. Diverse polycations, such as ethylenediamine-functionalized poly(glycidyl methacrylate) (PGED) with plentiful primary amines, secondary amines, and hydroxyl groups, demonstrate good gene transfection performances. Herein, a series of multifunctional cationic nanoparticles (PRP) consisting of photosensitizer cores and PGED shells are readily developed through simple dopamine-involving processes for versatile bioapplications. A series of experiments demonstrates that PRP nanoparticles are able to effectively mediate gene delivery in different cell lines. PRP nanoparticles are further validated to possess remarkable capability of combined PDT and gene therapy for complementary tumor treatment. In addition, because of their high dispersities in biological matrix, the PRP nanoparticles can also be used for in vitro and in vivo imaging with minimal aggregation-caused quenching. Therefore, such flexible nanoplatforms with photosensitizer cores and polycationic shells are very promising for multimodal tumor therapy with high efficacy.

Versatile Functionalization of Poly(methacrylic acid) Brushes with Series of Proteolytically Cleavable Peptides for Highly Sensitive Protease Assay.

The development of new materials for fast and sensitive protease assay is in demand for timely diagnosis of diseases, such as cardiovascular disease, cancers, and Alzheimer disease. Herein, poly(methacrylic acid) (PMAA) brushes were synthesized from the surfaces of silica nanoparticles via surface-initiated atom transfer radical polymerization (ATRP), and functionalized with series of proteolytically cleavable peptides for highly sensitive protease assay. Upon the proteolytic cleavage of the peptides, a short peptide fragment with fluorescent tag (GGK-FITC) is released to the solution, which can be easily detected with a benchtop fluorescence microscope. The grafting densities of PMAA brushes and peptides can be readily tuned by controlling the monomer concentrations of sodium methacrylate in the ATRP reaction. Because of the three-dimensional architecture of PMAA brushes, the loading amount of peptides can reach 21.4% of the total weight of functionalized silica particles (22.4 peptides/nm2), which is much higher than direct immobilization on silica nanoparticles without polymer brushes. Because of the high loading density of peptides, the limit of detection (LOD) of trypsin can reach 1.4 pM in buffer solution or 2.6 nM in nondiluted serum. By rational design of peptide substrates, the peptide-functionalized PMAA brushes can be readily expanded to detect other proteases, such as matrix metalloproteinase-2 (MMP-2), a virtual biomarker for many cancers, with an LOD of 1.1 pM. The proteolytically cleavable peptide-functionalized PMAA brushes offer a starting point for fast and sensitive protease assay.

Reduction-responsive multifunctional hyperbranched polyaminoglycosides with excellent antibacterial activity, biocompatibility and gene transfection capability.

There is an increasing demand in developing of multifunctional materials with good antibacterial activity, biocompatibility and drug/gene delivery capability for next-generation biomedical applications. To achieve this purpose, in this work series of hydroxyl-rich hyperbranched polyaminoglycosides of gentamicin, tobramycin, and neomycin (HP and SS-HP with redox-responsive disulfide bonds) were readily synthesized via ring-opening reactions in a one-pot manner. Both HP and SS-HP exhibit high antibacterial activity toward Escherichia coli and Staphylococcus aureus. Meanwhile, the hemolysis assay of the above materials shows good biocompatibility. Moreover, SS-HPs show excellent gene transfection efficiency in vitro due to the breakdown of reduction-responsive disulfide bonds. For an in vivo anti-tumor assay, the SS-HP/p53 complexes exhibit potent inhibition capability to the growth of tumors. This study provides a promising approach for the design of next-generation multifunctional biomedical materials.

Mechanistic study for immobilization of cysteine-labeled oligopeptides on UV-activated surfaces.

In this study, we report immobilization of cysteine-labeled oligopeptides on UV activated surfaces decorated with N,N-dimethyl-n-octadecyl-3-aminopropyltrimethoxysilyl chloride (DMOAP). Our result shows that cysteine group, regardless of its position in the oligopeptide, is essential for successful immobilization of oligopeptide on the UV-activated surface. A possible reaction mechanism is nucleophilic addition of thiolates to surface aldehyde groups generated during UV activation. By using this technique, we are able to incorporate anchoring points into oligopeptides through cysteine residues. Furthermore, immobilized oligopeptides on the UV-activated surface is very stable even under harsh washing conditions. Finally, we show that an HPQ-containing oligopeptide can be immobilized on the UV-activated surface, but the final surface density and its ability to bind streptavidin are affected by the position of cysteine and HPQ. An oligopeptide with a cysteine at the N-terminus and a HPQ motif at the C-terminus gives the highest binding signal in the streptavidin-binding assay. This result is potentially useful for the development of functional oligopeptide microarrays for detecting target protein molecules.

Antibody-free detection of human chorionic gonadotropin by use of liquid crystals.

Human chorionic gonadotropin (hCG) is an important biomarker for the diagnosis of pregnancy and cancers. In this study, we report an antibody-free and label-free mechanism for detecting hCG. To replace enzyme-labeled antibodies, we use a short oligopeptide as an hCG receptor to bind hCG. The short oligopeptide sequence, (N-)PPLRINRHILTR(-C), is identified after 5 rounds of screening by use of a phage library. After binding, liquid crystal (LC) is used to transduce the binding event into optical signals. The captured hCG can disrupt a thin layer (~6 µm) of LC covered on the surface. Depending on the initial concentration of hCG, LC gives distinct optical signals visible to the naked eye. The limit of detection (LOD) for this method is approximately 1 IU/mL (2 nM) in both phosphate-buffered saline and urine samples, and only 0.6 µL of hCG solution is required. This means that as little as 45.5 pg of hCG can be detected by this method. Compared to other detection methods for hCG, this detection method does not require the use of antibody and is label-free. It has the potential to become a portable diagnostic kit for hCG.

Oligopeptides functionalized surface plasmon resonance biosensors for detecting thiacloprid and imidacloprid.

By using phage display library, we identified two highly specific oligopeptide sequences RKRIRRMMPRPS and RNRHTHLRTRPR for binding neonicotinoids such as thiacloprid and imidacloprid. The former shows high affinity for thiacloprid whereas the latter shows high affinity for imidacloprid. Surprisingly, cross binding is minimal despite the similarity of the two molecules. To develop a neonicotinoid biosensor, these two oligopeptides are synthesized and immobilized on the surface of a surface plasmon resonance (SPR) chip with a bare-gold surface. This oligopeptide functionalized SPR biosensor can rapidly detect thiacloprid and imidacloprid in buffer solutions in a real-time manner. The limit of detection (LOD) for thiacloprid and imidacloprid is 1.2 µM and 0.9 µM, respectively.