Reiterated Targeting Peptides on the Nanoparticle Surface Significantly Promote Targeted Vascular Endothelial Growth Factor Gene Delivery to Stem Cells

Nonviral gene delivery vectors hold great promise for gene therapy due to the safety concerns with viral vectors. However, the application of nonviral vectors is hindered by their low transfection efficiency. Herein, in order to tackle this challenge, we developed a nonviral vector integrating lipids, sleeping beauty transposon system and 8-mer stem cell targeting peptides for safe and efficient gene delivery to hard-to-transfect mesenchymal stem cells (MSCs). The 8-mer MSC-targeting peptides, when synthetically reiterated in three folds and chemically presented on the surface, significantly promoted the resultant lipid-based nanoparticles (LBNs) to deliver VEGF gene into MSCs with a high transfection efficiency (∼52%) and long-lasting gene expression (for longer than 170 h) when compared to nonreiterated peptides. However, the reiterated stem cell targeting peptides do not enable the highly efficient gene transfer to other control cells. This work suggests that the surface presentation of the reiterated stem cell-targeting peptides on the nonviral vectors is a promising method for improving the efficiency of cell-specific nonviral gene transfection in stem cells

Synthesis and Characterization of Silklike Materials Containing the Calcium-Binding Sequence from Calbindin D9k or the Shell Nacreous Matrix Protein MSI60

Synthesis and Characterization of Silklike Materials Containing the Calcium-Binding Sequence from Calbindin D9k or the Shell Nacreous Matrix Protein MSI6

Protein-Induced Gold Nanoparticle Assembly for Improving the Photothermal Effect in Cancer Therapy

Gold nanoparticles (AuNPs) are promising photothermal agents for cancer therapy. However, the absorption of spherical AuNPs is weak in the desired tissue-penetrating near-infrared (NIR) window, resulting in low photothermal efficiency within this window. Here, we show that fibrous nanostructures assembled from spherical AuNPs since the templating effect of silk fibroin (SF) could red-shift the optical absorption to NIR and thus present improved photothermal efficiency within the NIR window. Specifically, negatively charged SF, a protein derived from Bombyx mori, was assembled into nanofibers due to the interaction with the positively charged AuNPs and concomitantly templated the AuNPs into fibrous nanostructures. The resultant AuNPs/SF nanofibers presented higher NIR light absorption at 808 nm and higher photothermal efficiency under 808 nm NIR irradiation than nonassembled AuNPs. In vitro and in vivo analyses proved that AuNPs/SF nanofibers could efficiently kill breast cancer cells and destruct breast cancer tumor tissues under one-time NIR irradiation for 6 min by photothermal therapy (PTT) but nonassembled AuNPs could not. This work suggests that the self-assembled AuNPs/SF nanofibers are effective photosensitizers for PTT, and biotemplated assembly of photothermal agents into highly ordered nanostructures is a promising approach to increasing the PTT efficiency

Injectable Phage-Loaded Microparticles Effectively Release Phages to Kill Methicillin-Resistant Staphylococcus aureus

The increasing prevalence of bacterial multidrug antibiotic resistance has led to a serious threat to public health, emphasizing the urgent need for alternative antibacterial therapeutics. Lytic phages, a class of viruses that selectively infect and kill bacteria, offer promising potential as alternatives to antibiotics. However, injectable carriers with a desired release profile remain to be developed to deliver them to infection sites. To address this challenge, phage-loaded microparticles (Phage-MPs) have been developed to deliver phages to the infection site and release phages for an optimal therapeutic effect. The Phage-MPs are synthesized by allowing phages to be electrostatically attached onto the porous polyethylenimine-modified silk fibroin microparticles (SF-MPs). The high specific surface area of SF-MPs allows them to efficiently load phages, reaching about 1.25 × 1010 pfu per mg of microparticles. The Phage-MPs could release phages in a controlled manner to achieve potent antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). Unlike the diffuse biodistribution of free phages post-intraperitoneal injection, Phage-MPs could continuously release phages to effectively boost the local phage concentration at the bacterial infection site after they are intraperitoneally injected into an abdominal MRSA-infected mouse model. In a mouse abdominal MRSA infection model, Phage-MPs significantly reduce the bacterial load in major organs, achieving an efficient therapeutic effect. Furthermore, Phage-MPs demonstrate outstanding biocompatibility both in vitro and in vivo. Overall, our research lays the foundation for a new generation of phage-based therapies to combat antibiotic-resistant bacterial infections

Tuning Molecular Weights of <i>Bombyx mori (B. mori)</i> Silk Sericin to Modify Its Assembly Structures and Materials Formation

<i>Bombyx mori (B. mori)</i> silk sericin is a protein with features desirable as a biomaterial, such as increased hydrophilicity and biodegradation, as well as resistance to oxidation, bacteria, and ultraviolet light. In contrast to other widely studied <i>B. mori</i> silk proteins such as fibroin, sericin is still unexplored as a building block for fabricating biomaterial, and thus a facile technique of processing it into a material is needed. Here, electrospinning technology was used to fabricate it into biomaterials from two forms of <i>B. mori</i> silk sericin with different molecular weights, one is a low (12.0 kDa) molecular sericin (LS) form and another is a high (66.0 kDa) molecular weight sericin (HS) form. Circular dichroism (CD) spectra showed that LS in hexafluoroacetone (HFA) solvent adopted a predominantly random coil conformation, whereas HS tended to form a β-sheet structure along with a large content of random coils. In addition, LS and HS in HFA solvent were found to form cylinder-like smaller nanoparticles and larger irregular aggregates before electrospinning, respectively. As a result, biomaterials based on microparticles and nanofibers were successfully fabricated by electrospinning of LS and HS dissolved in HFA, respectively. The cell viability and differentiation assay indicated that nanofibers and microparticles improved cell adhesion, growth, and differentiation, proving that the scaffolds electrospun from sericin are biocompatible regardless of its molecular weight. The microparticles, not common in electrospinning of silk proteins reported previously, were found to promote the osteogenic differentiation of mesenchymal stem cells in comparison to the nanofibers. This study suggested that molecular weight of sericin mediates its secondary structure and assembly structure, which in turn leads to a control of final morphology of the electrospun materials. The microparticles and nanofibers of sericin can be potentially used as building blocks for fabricating the scaffolds for tissue engineering

Polydopamine-Coated <i>Antheraea pernyi</i> (<i>A.</i> <i>pernyi</i>) Silk Fibroin Films Promote Cell Adhesion and Wound Healing in Skin Tissue Repair

Wound dressings are important materials for the successful recovery of skin trauma. Traditional wound dressings such as gauzes are not efficient in wound healing. Here we show that silk fibroin, spun from a wild silkworm Antheraea pernyi (A. pernyi) and rich in Arg-Gly-Asp (RGD) sequences, can be developed into a wound dressing after proper modification for improving the cell adhesion to accelerate the skin repair. Specifically, polydopamine (PDA) was coated on an A. pernyi silk fibroin (AF) film to form the PAF film to achieve enhanced cell adhesion and would healing. The PDA coating significantly increased the roughness and hydrophilicity of the AF film and thus its protein absorption capability. Furthermore, the PAF films promoted the adhesion and migration of mesenchymal stem cells (MSCs) in the in vitro wound healing assay. In vivo testing confirmed that wound covered with the PAF film was completely healed with the formation of the new skin and hair within 14 days post trauma. Histological examination indicated that, compared to the AF film and gauze control, the PAF film did not cause significant inflammation in the wound but promoted the epithelialization and well-organized collagen deposition in the dermis. This work indicates that AF films coated with PDA are promising wound dressings for skin tissue repair

pH-Triggered Charge-Reversal Silk Sericin-Based Nanoparticles for Enhanced Cellular Uptake and Doxorubicin Delivery

Silk-based nanoparticles have been exhibiting an increasing potential for use as drug delivery systems due to their great versatility. To extend applications of silk sericin in nanomedicine and improve the performance of silk-based nanoparticles in drug delivery, a facile two-step cross-linking is attempted, for the first time, to fabricate surface charge-reversal silk sericin-based nanoparticles (SSC@NPs) by introducing chitosan into silk sericin. The results suggest stable SSC@NPs are formed with a negative surface charge in a neutral environment. Under mildly acidic conditions, however, surface charge of SSC@NPs undergoes a negative-to-positive conversion. It proves that pH can regulate surface charge of SSC@NPs. It is the increased amino/carboxyl ratio in SSC@NPs that explains the underlying mechanism of the charge conversion property of SSC@NPs. Furthermore, the positively charged SSC@NPs triggered by tumor acidic microenvironment (pH 6.0) result in a 6.0-fold higher cellular uptake than the negatively charged counterparts at pH 7.4. In addition, an anticancer drug doxorubicin (DOX) is readily loaded into SSC@NPs and released in a pH-dependent manner. This work provides a simple method to fabricate smart pH-responsive nanoparticles for anticancer drug delivery

Identification of Novel Short BaTiO₃‑Binding/Nucleating Peptides for Phage-Templated in Situ Synthesis of BaTiO₃ Polycrystalline Nanowires at Room Temperature

Ferroelectric materials, such as tetragonal barium titanate (BaTiO3), have been widely used in a variety of areas including bioimaging, biosensing, and high power switching devices. However, conventional methods for the synthesis of tetragonal phase BaTiO3 usually require toxic organic reagents and high temperature treatments, and are thus not environment-friendly and energy-efficient. Here, we took advantage of the phage display technique to develop a novel strategy for the synthesis of BaTiO3 nanowires. We identified a short BaTiO3-binding/nucleating peptide, CRGATPMSC (named RS), from a phage-displayed random peptide library by biopanning technique and then genetically fused the peptide to the major coat protein (pVIII) of filamentous M13 phages to form the pVIII-RS phages. We found that the resultant phages could not only bind with the presynthesized BaTiO3 crystals but also induce the nucleation of uniform tetragonal BaTiO3 nanocrystals at room temperature and without the use of toxic reagents to form one-dimensional polycrystalline BaTiO3 nanowires. This approach enables the green synthesis of BaTiO3 polycrystalline nanowires with potential applications in bioimaging and biosensing fields

Polyethyleneimine-Enabled Tunable Electrostatic Nanoparticle Assemblies on Ultrathin Protein Nanofibers for Plasmonics-Based Solar Energy Harvesting

Controlled assembly of nanoparticles (NPs) onto ultrathin, protein-based biotemplates was previously achieved mainly through the chemical or genetic engineering of the surface chemistry of the templates. However, not only is this approach tedious and complicated, but also such surface engineering is case-specific and lacks generality. Biotemplates with one type of surface chemistry are only suitable to assemble one or a few types of NPs, and different engineering methods are demanded for different types of nanomaterials. Here, instead of engineering the biotemplates, we developed a simple, universal plug-and-play approach through the engineering of the surface chemistry of NPs. We discovered that coating NPs with short-chain polyethyleneimine (PEI) can lead to the highly efficient and controllable electrostatic assembly of NPs onto unmodified protein-based bionanofibers. The PEI molecular weight played a key role in the NP–biotemplate interaction. Specifically, we found that only low-molecular-weight PEI-coated NPs could be loaded densely onto the bionanofibers, while the high-molecular-weight PEI, which individually carried more charges, only led to low-density NP assembly. Our method is facile and universal in several ways. It can assemble NPs of various compositions, sizes, and surface ligand structures onto different wild-type bionanofibers, including flagella, bacteriophages, and pili, without the hassle of the case-specific surface engineering of the biotemplates. Such 1D nanoparticle assembly has its unique advantage as starting materials in fabricating 3D structured linear plasmonic nanochains with broad optical bands for solar harvesting applications