Fabrication and in vitro biocompatibilities of fibrous biocomposites consisting of PCL and M13 bacteriophage-conjugated alginate for bone tissue engineering

Electric Field Polarity Controls Distribution of Viral Bioreceptors within Near-Field Electrospun Biohybrid Microfiber Optical Biosensors

Microorganisms (e.g., bacteria, fungi, and viruses) add indispensable functionality to a range of electrospun polymer materials and devices. The optimal distribution of bioactive agents on either the interior or exterior of the fiber is application-specific. Current microbe surface immobilization strategies and core-confinement techniques continue to pose a number of challenges. Here, we explore a simple strategy, utilizing electrostatic forces, to control the migration and surface concentration of the M13 bacteriophage within near-field electrospun poly(vinyl alcohol) (PVA) microfibers. Both the surface charge of the electrospun virus and the applied electric field polarity altered microbe placement. When doped with Rhodamine 6G (R6G), the circular microfiber cross sections formed active whispering gallery mode (WGM) resonators. These relatively high-quality (Q) optical cavities enabled us to sensitively probe the virus content of their outer layer, while functioning as label-free optical biosensors with phage-based streptavidin biorecognition elements. Coulomb forces displayed significant control over M13 surface coverage during near-field electrospinning, increasing biosensor response by nearly a factor of 4 to 1310 nM streptavidin. These findings are an important demonstration of electrostatic forces as a simple, yet adaptable method to enhance biohybrid fiber functionality and performance by tailoring microbe distribution.

Evaluation of bacteriophages for the alleviation of potential bacterial contamination risks in developmental engineering

This research aimed to address the potential bacterial contamination risks in developmental engineering (DE) using bacteriophages. To compare and contrast the exemplar Escherichia coli T4 and M13 bacteriophages, human dermal fibroblasts cultivated on culture plates, natural cellulosic scaffolds, and poly(methyl methacrylate) (PMMA) particles were utilized as two-dimensional (2D) cell, three-dimensional (3D) tissue, and modular tissue culture models, respectively. When directly introduced into these distinct culture systems, both phages survived, exhibited no significant effects on the cultured cells or tissues, yet displayed their potentials to alleviate the infections caused by corresponding bacterial host cells. Apart from direct addition into the culture medium, both phages were also coated on PMMA, polystyrene, poly(lactic acid) particles with different diameters (5, 10, 30, and 100 µm) and cellulosic scaffolds. The coated phages endured the coating processes and demonstrated their viabilities in plaque assays. Further testing indicated that the phages coated on the PMMA particles tolerated multiple deliberate rinses and centrifugations, but not thermal treatment at 60-80°C. In summary, T4 and M13 bacteriophages not only manifested their antibacterial functions in diverse 2D cell, 3D tissue, and modular tissue culture systems, but also demonstrated their potentials of coating modular scaffolds to alleviate the bacterial contamination risks in DE.

Genetically engineered bacteriophages as novel nanomaterials: applications beyond antimicrobial agents

Bacteriophages, also known as phages, are viruses that replicate in bacteria and archaea. Phages were initially discovered as antimicrobial agents, and they have been used as therapeutic agents for bacterial infection in a process known as "phage therapy." Recently, phages have been investigated as functional nanomaterials in a variety of areas, as they can function not only as therapeutic agents but also as biosensors and tissue regenerative materials. Phages are nontoxic to humans, and they possess self-assembled nanostructures and functional properties. Additionally, phages can be easily genetically modified to display specific peptides or to screen for functional peptides via phage display. Here, we demonstrated the application of phage nanomaterials in the context of tissue engineering, sensing, and probing.

Identification of a Specific Phage as Growth Factor Alternative Promoting the Recruitment and Differentiation of MSCs in Bone Tissue Regeneration

Inefficient use and loss of exogenously implanted mesenchymal stem cells (MSCs) are major concerns in MSCs-based bone tissue engineering. It is a promising approach to overcome the above issues by recruiting and regulation of endogenous MSCs. However, there are few substances that can recruit MSCs effectively and specifically to the site of bone injury. In this study, we identified a phage clone (termed P11) with specific affinity for MSCs through phage display biopanning, and further investigated the effects of P11 on the cytological behavior of MSCs and macrophages. The results showed that P11 could bind MSCs specifically and promote the proliferation and migration of MSCs. Meanwhile, P11 could polarize macrophages to the M1 phenotype and significantly changed their morphology, which further enhanced the chemotaxis of MSCs. Additionally, RNA-seq results revealed that P11 could promote the secretion of osteogenesis-related markers in MSCs through the TPL2-MEK-ERK signaling pathway. Altogether, P11 has great potential to be used as growth factor alternatives in bone tissue engineering, with the advantages of cheaper and stable activity. Our study also advances the understanding of the effects of phages on macrophages and MSCs, and provides a new idea for the development in the field of phage-based tissue engineering.

Electropsun Polycaprolactone Fibres in Bone Tissue Engineering: A Review

Regeneration of bone tissue requires novel load bearing, biocompatible materials that support adhesion, spreading, proliferation, differentiation, mineralization, ECM production and maturation of bone-forming cells. Polycaprolactone (PCL) has many advantages as a biomaterial for scaffold production including tuneable biodegradation, relatively high mechanical toughness at physiological temperature. Electrospinning produces nanofibrous porous matrices that mimic many properties of natural tissue extracellular matrix with regard to surface area, porosity and fibre alignment. The biocompatibility and hydrophilicity of PCL nanofibres can be improved by combining PCL with other biomaterials to form composite scaffolds for bone regeneration. This work reviews the most recent research on synthesis, characterization and cellular response to nanofibrous PCL scaffolds and the composites of PCL with other natural and synthetic materials for bone tissue engineering.

Experimental and numerical evaluation of a genetically engineered M13 bacteriophage with high sensitivity and selectivity for 2,4,6-trinitrotoluene

Selective and sensitive detection of desired targets is very critical in sensor design. Here, we report a genetically engineered M13 bacteriophage-based sensor system evaluated by quantum mechanics (QM) calculations. Phage display is a facile way to develop the desired peptide sequences, but the resulting sequences can be imperfect peptides for binding of target molecules. A TNT binding peptide (WHW) carrying phage was self-assembled to fabricate thin films and tested for the sensitive and selective surface plasmon resonance-based detection of TNT molecules at the 500 femtomole level. SPR studies performed with the WHW peptide and control peptides (WAW, WHA, AHW) were well-matched with those of the QM calculations. Our combined method between phage engineering and QM calculation will significantly enhance our ability to design selective and sensitive sensors.

Promoting Endothelial Cell Affinity and Antithrombogenicity of Polytetrafluoroethylene (PTFE) by Mussel-Inspired Modification and RGD/Heparin Grafting

When used as small-diameter vascular grafts (SDVGs), synthetic biomedical materials like polytetrafluoroethylene (PTFE) may induce thrombosis and intimal hyperplasia due to the lack of an endothelial cell layer. Modification of the PTFE in an aqueous solution is difficult because of its hydrophobicity. Herein, aiming to simultaneously promote endothelial cell affinity and antithrombogenicity, a mussel-inspired modification approach was employed to enable the grafting of various bioactive molecules like RGD and heparin. This approach involves a series of pragmatic steps including oxygen plasma treatment, dopamine (DA) coating, polyethylenimine (PEI) grafting, and RGD or RGD/heparin immobilization. Successful modification in each step was verified via Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Plasma treatment increased the hydrophilicity of PTFE, thereby allowing it to be efficiently coated with dopamine. Grafting of dopamine, RGD, and heparin led to an increase in surface roughness and a decrease in water contact angle due to increased surface energy. Platelet adhesion increased after dopamine and RGD modification, but it dramatically decreased when heparin was introduced. All of these modifications, especially the incorporation of RGD, showed favorable effects on endothelial cell attachment, viability, and proliferation. Due to strong cell-substrate interactions between endothelial cells and RGD, the RGD/heparin-grafted PTFE demonstrated high endothelial cell affinity. This facile modification method is highly suitable for all hydrophobic surfaces and provides a promising technique for SDVG modification to stimulate fast endothelialization and effective antithrombosis.

Colorimetric and optical Hg(ii) ion sensor developed with conjugates of M13-bacteriophage and silver nanoparticles

Hg(ii) produces an AgHg amalgam on a conjugate of Ag nanoparticles and M13-bacteriophage, which effectively quenches the optical absorption of the Ag nanoparticles.

pH-Modulating Poly(ethylene glycol)/Alginate Hydrogel Dressings for the Treatment of Chronic Wounds

The development of chronic wounds has been frequently associated with alkaline pH values. The application of pH-modulating wound dressings can, therefore, be a promising treatment option to promote normal wound healing. This study reports on the development and characterization of acidic hydrogel dressings based on interpenetrating poly(ethylene glycol) diacrylate/acrylic acid/alginate networks. The incorporation of ionizable carboxylic acid groups results in high liquid uptake up to 500%. The combination of two separate polymer networks significantly improves the tensile and compressive stability. In a 2D cell migration assay, the application of hydrogels (0% to 1.5% acrylic acid) results in complete "wound" closure; hydrogels with 0.25% acrylic acid significantly increase the cell migration velocity to 19.8 ± 1.9 µm h^-1 . The most promising formulation (hydrogels with 0.25% acrylic acid) is tested on 3D human skin constructs, increasing keratinocyte ingrowth into the wound by 164%.

A mechanically improved virus-based hybrid scaffold for bone tissue regeneration

A hybrid scaffold (M13-phage/alginate and PCL) was proposed as a biomedical scaffold.