Non-intrusive quality appraisal of differentiation-induced cardiovascular stem cells using E-Nose sensor technology

Stem cell technology holds immense potential for revolutionizing medicine, particularly in regenerative treatment for heart disease. The unique capacity of stem cells to differentiate into diverse cell types offers promise in repairing damaged tissues and implanting organs. Ensuring the quality of differentiated cells, essential for specific functions, demands in-depth analysis. However, this process consumes time and incurs substantial costs while invasive methods may alter stem cell features during differentiation and deplete cell numbers. To address these challenges, we propose a non-invasive strategy, using cellular respiration, to assess the quality of differentiation-induced stem cells, notably cardiovascular stem cells. This evaluation employs an electronic nose (E-Nose) and neural pattern separation (NPS). Our goal is to assess differentiation-induced cardiac stem cells (DICs) quality through E-Nose data analysis and compare it with standard commercial human cells (SCHCs). Sensitivity and specificity were evaluated by interacting SCHCs and DICs with the E-Nose, achieving over 90% classification accuracy. Employing selective combinations optimized by NPS, E-Nose successfully classified all six cell types. Consequently, the relative similarity among DICs like cardiomyocytes, endothelial cells with SCHCs was established relied on comparing response data from the E-Nose sensor without resorting to complex evaluations.

Detection of Micrometer-Sized Virus Aerosols by Using a Real-Time Bioaerosol Monitoring System

This study investigates a real-time handheld bioaerosol monitoring system for the detection of biological particles using UV-LED and light-induced fluorescence technology. Biological particles produce both scattering and fluorescence signals simultaneously, which can help distinguish them from general particles. The detected scattering, fluorescence, and simultaneous signals are then converted into photon signals and categorized based on predetermined criteria. A reliable biological particle generator was required to validate the performance of the system. This study explores the use of an M13 bacteriophage as a virus simulant of biological agents and employs a customized inkjet aerosol generator to produce M13 bacteriophage aerosols of a specific size by controlling the concentration of M13. We confirmed that micro-sized, narrowly dispersed M13 aerosols were efficiently generated. Additionally, we confirmed the performance of this real-time handheld bioaerosol monitoring system by detecting viruses.

Combining a Base Deaminase Mutator with Phage-Assisted Evolution

Phage-assisted evolution has emerged as a powerful technique for improving a protein's function by using mutagenesis and selective pressure. However, mutations typically occur throughout the host's genome and are not limited to the gene-of-interest (GOI): these undesirable genomic mutations can yield host cells that circumvent the system's selective pressure. Our system targets mutations specifically toward the GOI by combining T7 targeted mutagenesis and phage-assisted evolution. This system improves the structure and function of proteins by accumulating favorable mutations that can change its binding affinity, specificity, and activity.

Designing M13 Bacteriophage and Fe-Nanonest Self-Assembly System for Universal and Facile Preparation of Metal Single Atoms as Stable Mimicking Enzymes

Metal single-atom catalysts (MSACs) possess multiple advantages in chemical synthesis; their efficient fabrication routes, however, remain a challenge to date. Here, an interdisciplinary design using M13 bacteriophage virus as a biotemplate to carry Fe nanoclusters, which we figuratively call "Fe-nanonests", is proposed to enable facile and versatile synthesis of MSACs. The feasibility and generality of this self-assembly method was demonstrated by the observation of six different metal single atoms (MSAs) including Ag, Pt, Pd, Zn, Cu, and Ni. With Pd as a representative, key factors dominating the fabrication were determined. The Pd single atoms exhibited excellent horseradish peroxidase (HRP)-like activity, which was further improved by 50% via genetic editing of the M13 pVIII protein terminals. Excellent stability was also observed in the quantification of acid phosphatase, a cancer predictor. X-ray absorption near-edge structure spectroscopy has been applied to the analysis of Pd single atoms as well, and the Pd-N4 coordination explained the mechanism of high HRP-like catalytic activity. The MSAs synthesized by the M13 phage and Fe-nanonest self-assembly method show promising prospects in non-cold-chain medical detection applications.

M13KO7 bacteriophage enables Potato Virus Y detection

IMPORTANCE

In this study, we confirmed the binding of M13KO7 to Potato virus Y (PVY) using enzyme-linked immunosorbent assay. M13KO7 is a "bald" bacteriophage in which no recombinant antibody is displayed. M13KO7 is easy to propagate by using Escherichia coli, making this method more reasonable in economic perspective. Based on this study, we suggest that M13KO7 detection system has applicability as a novel biological tool for the detection of PVY.

Sensor development for multiple simultaneous classifications using genetically engineered M13 bacteriophages

Sensors for detecting infinitesimal amounts of chemicals in air have been widely developed because they can identify the origin of chemicals. These sensing technologies are also used to determine the variety and freshness of fresh food and detect explosives, hazardous chemicals, environmental hormones, and diseases using exhaled gases. However, there is still a need to rapidly develop portable and highly sensitive sensors that respond to complex environments. Here, we show an efficient method for optimising an M13 bacteriophage-based multi-array colourimetric sensor for multiple simultaneous classifications. Apples, which are difficult to classify due to many varieties in distribution, were selected for classifying targets. M13 was adopted to fabricate a multi-array colourimetric sensor using the self-templating process since a chemical property of major coat protein p8 consisting of the M13 body can be manipulated by genetic engineering to respond to various target substances. The twenty sensor units, which consisted of different types of manipulated M13, exhibited colour changes because of the change of photonic crystal-like nanostructure when they were exposed to target substances associated with apples. The classification success rate of the optimal sensor combinations was achieved with high accuracy for the apple variety (100%), four standard fragrances (100%), and aging (84.5%) simultaneously. We expect that this optimisation technique can be used for rapid sensor development capable of multiple simultaneous classifications in various fields, such as medical diagnosis, hazardous environment monitoring, and the food industry, where sensors need to be developed in response to complex environments consisting of various targets.

Effects of the Magnetic Orientation of M13 Bacteriophage on Phage Display Selection

Although phage display selection using a library of M13 bacteriophage has become a powerful tool for finding peptides that bind to target materials on demand, a remaining concern of this method is the interference by the M13 main body, which is a huge filament >103  times larger than the displayed peptide, and therefore would nonspecifically adhere to the target or sterically inhibit the binding of the displayed peptide. Meanwhile, filamentous phages are known to be orientable by an external magnetic field. If M13 filaments are magnetically oriented during the library selection, their angular arrangement relative to the target surface would be changed, being expected to control the interference by the M13 main body. This study reports that the magnetic orientation of M13 filaments vertical to the target surface significantly affects the selection. When the target surface was affinitive to the M13 main body, this orientation notably suppressed the nonspecific adhesion. Furthermore, when the target surface was less affinitive to the M13 main body and intrinsically free from the nonspecific adhesion, this orientation drastically changed the population of M13 clones obtained through library selection. The method of using no chemicals but only a physical stimulus is simple, clean, and expected to expand the scope of phage display selection.

M13 Bacteriophage-Assisted Recognition and Signal Spatiotemporal Separation Enabling Ultrasensitive Light Scattering Immunoassay

The demand for the ultrasensitive and rapid quantitative analysis of trace target analytes has become increasingly urgent. However, the sensitivity of traditional immunoassay-based detection methods is limited due to the contradiction between molecular recognition and signal amplification caused by the size effect of nanoprobes. To address this dilemma, we describe versatile M13 phage-assisted immunorecognition and signal transduction spatiotemporal separation that enable ultrasensitive light-scattering immunoassay systems for the quantitative detection of low-abundance target analytes. The newly developed immunoassay strategy combines the M13 phage-assisted light scattering signal fluctuations of gold nanoparticles (AuNPs) with gold in situ growth (GISG) technology. Given the synergy of M13 phage-mediated leverage effect and GISG-amplified light scattering signal modulation, the practical detection capability of this strategy can achieve the ultrasensitive and rapid quantification of ochratoxin A and alpha-fetoprotein in real samples at the subfemtomolar level within 50 min, displaying about 4 orders of magnitude enhancement in sensitivity compared with traditional phage-based ELISA. To further improve the sensitivity of our immunoassay, the biotin-streptavidin amplification scheme is implemented to detect severe acute respiratory syndrome coronavirus 2 spike protein down to the attomolar range. Overall, this study offers a direction for ultrasensitive quantitative detection of target analytes by the synergistic combination of M13 phage-mediated leverage effect and GISG-amplified light scattering signal modulation.

Understanding the Role of M13 Bacteriophage Thin Films on a Metallic Nanostructure through a Standard and Dynamic Model

The dynamic and surface manipulation of the M13 bacteriophage via the meeting application demands the creation of a pathway to design efficient applications with high selectivity and responsivity rates. Here, we report the role of the M13 bacteriophage thin film layer that is deposited on an optical nanostructure involving gold nanoparticles/SiO₂/Si, as well as its influence on optical and geometrical properties. The thickness of the M13 bacteriophage layer was controlled by varying either the concentration or humidity exposure levels, and optical studies were conducted. We designed a standard and dynamic model based upon three-dimensional finite-difference time-domain (3D FDTD) simulations that distinguished the respective necessity of each model under variable conditions. As seen in the experiments, the origin of respective peak wavelength positions was addressed in detail with the help of simulations. The importance of the dynamic model was noted when humidity-based experiments were conducted. Upon introducing varied humidity levels, the dynamic model predicted changes in plasmonic properties as a function of changes in NP positioning, gap size, and effective index (this approach agreed with the experiments and simulated results). We believe that this work will provide fundamental insight into understanding and interpreting the geometrical and optical properties of the nanostructures that involve the M13 bacteriophage. By combining such significant plasmonic properties with the numerous benefits of M13 bacteriophage (like low-cost fabrication, multi-wavelength optical characteristics devised from a single structure, reproducibility, reversible characteristics, and surface modification to suit application requirements), it is possible to develop highly efficient integrated plasmonic biomaterial-based sensor nanostructures.

Engineered Living Bacteriophage-Enabled Self-Adjuvanting Hydrogel for Remodeling Tumor Microenvironment and Cancer Therapy

Due to the complexity and heterogeneity in the tumor microenvironment, the efficacy of breast cancer treatment has been significantly impeded. Here, we established a living system using an engineered M13 bacteriophage through chemical cross-linking and biomineralization to remodel the tumor microenvironment. Chemically cross-linking of the engineered bacteriophage gel (M13 Gel) could in situ synthesize photothermal palladium nanoparticles (PdNPs) on the pVIII capsid protein to obtain M13@Pd Gel. In addition, NLG919 was further loaded into a gel to form (M13@Pd/NLG gel) for down-regulating the expression of tryptophan metabolic enzyme indoleamine 2,3-dioxygenase 1 (IDO1). Both in vitro and in vivo studies showed that the M13 bacteriophage served not only as a cargo-loaded device but also as a self-immune adjuvant, which induced the immunogenic death of tumor cells effectively and down-regulated IDO1 expression. Such a bioactive gel system constructed by natural living materials could reverse immunosuppression and significantly improve the anti-breast cancer response.

The development progress of multi-array colourimetric sensors based on the M13 bacteriophage

Techniques for detecting chemicals dispersed at low concentrations in air continue to evolve. These techniques can be applied not only to manage the quality of agricultural products using a post-ripening process but also to establish a safety prevention system by detecting harmful gases and diagnosing diseases. Recently, techniques for rapid response to various chemicals and detection in complex and noisy environments have been developed using M13 bacteriophage-based sensors. In this review, M13 bacteriophage-based multi-array colourimetric sensors for the development of an electronic nose is discussed. The self-templating process was adapted to fabricate a colour band structure consisting of an M13 bacteriophage. To detect diverse target chemicals, the colour band was utilised with wild and genetically engineered M13 bacteriophages to enhance their sensing abilities. Multi-array colourimetric sensors were optimised for application in complex and noisy environments based on simulation and deep learning analysis. The development of a multi-array colourimetric sensor platform based on the M13 bacteriophage is likely to result in significant advances in the detection of various harmful gases and the diagnosis of various diseases based on exhaled gas in the future.

Antibody Phage Display

The application of antibodies has transcended across many areas of work but mainly as a research tool, for diagnostic and for therapeutic applications. Antibodies are immunoproteins from vertebrates that have the unique property of specifically binding foreign molecules and distinguish target antigens. This property allows antibodies to effectively protect the host from infections. Apart from the hybridoma technology using transgenic animals, antibody phage display is commonly considered the gold standard technique for the isolation of human monoclonal antibodies. The concept of antibody phage display surrounds the ability to display antibody fragments on the surface of M13 bacteriophage particles with the corresponding gene packaged within the particle. A repetitive in vitro affinity based selection process permits the enrichment of target specific binders. This process of recombinant human monoclonal antibody generation also enables additional engineering for various applications. This makes phage display an indispensable technique for antibody development and engineering activities.

Multiarray Biosensor for Diagnosing Lung Cancer Based on Gap Plasmonic Color Films

Adaptable and sensitive materials are essential for the development of advanced sensor systems such as bio and chemical sensors. Biomaterials can be used to develop multifunctional biosensor applications using genetic engineering. In particular, a plasmonic sensor system using a coupled film nanostructure with tunable gap sizes is a potential candidate in optical sensors because of its simple fabrication, stability, extensive tuning range, and sensitivity to small changes. Although this system has shown a good ability to eliminate humidity as an interferant, its performance in real-world environments is limited by low selectivity. To overcome these issues, we demonstrated the rapid response of gap plasmonic color sensors by utilizing metal nanostructures combined with genetically engineered M13 bacteriophages to detect volatile organic compounds (VOCs) and diagnose lung cancer from breath samples. The M13 bacteriophage was chosen as a recognition element because the structural protein capsid can readily be modified to target the desired analyte. Consequently, the VOCs from various functional groups were distinguished by using a multiarray biosensor based on a gap plasmonic color film observed by hierarchical cluster analysis. Furthermore, the lung cancer breath samples collected from 70 healthy participants and 50 lung cancer patients were successfully classified with a high rate of over 89% through supporting machine learning analysis.

M13 bacteriophage as biometric component for orderly assembly of dynamic light scattering immunosensor

The ordered assembly of nanostructure is an effective strategy used to manipulate the hydrodynamic diameter (D_H) of nanoparticles. Herein, a versatile dynamic light scattering (DLS) immunosensing platform is presented to sensitively detect small molecules and biomacromolecules by using the M13 phage as the building module to order the assembly of gold nanoflowers and gold-coated magnetic nanoparticles, respectively. After the directional assembly of M13 phage, the D_H of the probes was significantly increased due to its larger filamentous structure, thus improving the detection sensitivity of the DLS immunosensor. The designed M13 assembled DLS immunosensor with competitive and sandwich formats showed high sensitivities for ochratoxin A and alpha-fetoprotein in real corn and undiluted serum samples, with the detection limits of 1.37 and 57 pg/mL, respectively. These values are approximately 15.8 and 164.9 times lower than those of traditional phage-based enzyme-linked immunosorbent assays. Collectively, this work provides a promising strategy to manipulate the D_H of nanoparticles by highly evolved biomaterials such as engineered M13 phages and opens upon a new direction for developing DLS immunosensors to detect various targets by the fusion expression of special peptide or nanobody on the pIII or pVIII protein of M13 phage.

Advanced photodynamic therapy with an engineered M13 phage targeting EGFR: Mitochondrial localization and autophagy induction in ovarian cancer cell lines

Photodynamic therapy (PDT) is a potential synergistic approach to chemotherapy for treating ovarian cancer, the most lethal gynecologic malignancy. Here we used M13 bacteriophage as a targeted vector for the efficient photodynamic killing of SKOV3 and COV362 cells. The M13 phage was refactored (M13_r) to display an EGFR binding peptide in its tip that is frequently overexpressed in ovarian cancer. The refactored phage was conjugated with chlorin e6 (Ce6), one of the most widely used photosensitizers (M13_r-Ce6). The new platform, upon irradiation, generated ROS by type I mechanism and showed activity in killing SKOV3 and COV362 cells even at concentrations in which Ce6 alone was ineffective. A microscopy analysis demonstrated an enhanced cellular uptake of M13_r-Ce6 compared to free Ce6 and its mitochondrial localization. Western blot analysis revealed significant downregulation in the expression of EGFR in cells exposed to M13_r-Ce6 after PDT. Following PDT treatment, autophagy induction was supported by an increased expression of LC3II, along with a raised autophagic fluorescent signal, as observed by fluorescence microscopy analysis for autophagosome visualization. As a conclusion we have herein proposed a bacteriophage-based receptor targeted photodynamic therapy for EGFR-positive ovarian cancer.

Improved Light Harvesting of Fiber-Shaped Dye-Sensitized Solar Cells by Using a Bacteriophage Doping Method

Fiber-shaped solar cells (FSCs) with flexibility, wearability, and wearability have emerged as a topic of intensive interest and development in recent years. Although the development of this material is still in its early stages, bacteriophage-metallic nanostructures, which exhibit prominent localized surface plasmon resonance (LSPR) properties, are one such material that has been utilized to further improve the power conversion efficiency (PCE) of solar cells. This study confirmed that fiber-shaped dye-sensitized solar cells (FDSSCs) enhanced by silver nanoparticles-embedded M13 bacteriophage (Ag@M13) can be developed as solar cell devices with better PCE than the solar cells without them. The PCE of FDSSCs was improved by adding the Ag@M13 into an iodine species (I⁻/I₃⁻) based electrolyte, which is used for redox couple reactions. The optimized Ag@M13 enhanced FDSSC showed a PCE of up to 5.80%, which was improved by 16.7% compared to that of the reference device with 4.97%.

Polarization Angle Dependence of Optical Gain in a Hybrid Structure of Alexa-Flour 488/M13 Bacteriophage

We measured optical modal gain of a dye–virus hybrid structure using a variable stripe length method, where Alexa-fluor-488 dye was coated on a virus assembly of M13 bacteriophage. Inspired by the structural periodicity of the wrinkle-like virus assembly, the edge emission of amplified spontaneous emission was measured for increasing excited optical stripe length, which was aligned to be either parallel or perpendicular to the wrinkle alignment. We found that the edge emission showed a strong optical anisotropy, and a spectral etalon also appeared in the gain spectrum. These results can be attributed to the corrugated structure, which causes a similar effect to a DFB laser, and we also estimated effective cavity lengths.

Dramatically Enhancing the Sensitivity of Immunoassay for Ochratoxin A Detection by Cascade-Amplifying Enzyme Loading

Enzyme-linked immunosorbent assay (ELISA) is widely used in the routine screening of mycotoxin contamination in various agricultural and food products. Herein, a cascade-amplifying system was introduced to dramatically promote the sensitivity of an immunoassay for ochratoxin A (OTA) detection. Specifically, a biotinylated M13 bacteriophage was introduced as a biofunctional competing antigen, in which a seven-peptide OTA mimotope fused on the p3 protein of M13 was used to specifically recognize an anti-OTA monoclonal antibody, and the biotin molecules modified on capsid p8 proteins were used in loading numerous streptavidin-labeled polymeric horseradish peroxidases (HRPs). Owing to the abundance of biotinylated p8 proteins in M13 and the high molar ratio between HRP and streptavidin in streptavidin-polyHRP, the loading amount of HRP enzymes on the M13 bacteriophage were greatly boosted. Hence, the proposed method exhibited high sensitivity, with a limit of detection of 2.0 pg/mL for OTA detection, which was 250-fold lower than that of conventional ELISA. In addition, the proposed method showed a slight cross-reaction of 2.3% to OTB, a negligible cross-reaction for other common mycotoxins, and an acceptable accuracy for OTA quantitative detection in real corn samples. The practicability of the method was further confirmed with a traditional HRP-based ELISA method. In conclusion, the biotinylated bacteriophage and polyHRP structure showed potential as a cascade-amplifying enzyme loading system for ultra-trace OTA detemination, and its application can be extended to the detection of other analytes by altering specific mimic peptide sequences.

Eco-Friendly Fluorescent ELISA Based on Bifunctional Phage for Ultrasensitive Detection of Ochratoxin A in Corn

Conventional enzyme-linked immunosorbent assay (ELISA) is commonly used for Ochratoxin A (OTA) screening, but it is limited by low sensitivity and harmful competing antigens of enzyme-OTA conjugates. Herein, a bifunctional M13 bacteriophage with OTA mimotopes fused on the p3 protein and biotin modified on major p8 proteins was introduced as an eco-friendly competing antigen and enzyme container for enhanced sensitivity. Mercaptopropionic acid-modified quantum dots (MPA-QDs), which are extremely sensitive to hydrogen peroxide, were chosen as fluorescent signal transducers that could manifest glucose oxidase-induced fluorescence quenching in the presence of glucose. On these bases, a highly sensitive and eco-friendly fluorescent immunoassay for OTA sensing was developed. Under optimized conditions, the proposed method demonstrates a good linear detection of OTA from 4.8 to 625 pg/mL and a limit of detection (LOD) of 5.39 pg/mL. The LOD is approximately 26-fold lower than that of a conventional horse radish peroxidase (HRP) based ELISA and six-fold lower than that of a GOx-OTA conjugate-based fluorescent ELISA. The proposed method also shows great specificity and accepted accuracy for analyzing OTA in real corn samples. The detection results are highly consistent with those obtained using the ultra-performance liquid chromatography-fluorescence detection method, indicating the high reliability of the proposed method for OTA detection. In conclusion, the proposed method is an excellent OTA screening platform over a conventional ELISA and can be easily extended for sensing other analytes by altering specific mimic peptide sequences in phages.

Fabrication of Chiral M13 Bacteriophage Film by Evaporation-Induced Self-Assembly

Biomacromolecules are likely to undergo self-assembly and show specific collective behavior concentrated in the medium. Although the assembly procedures have been studied for unraveling their mysteries, there are few cases to directly demonstrate the collective behavior and phase transition process in dynamic systems. In the contribution, the drying process of M13 droplet is investigated, and can be successfully simulated by a doctor blade coating method. The morphologies in the deposited film are measured by atomic force microscopy and the liquid crystal phase development is captured in real time using polarized optical microscope. Collective behaviors near the contact line are characterized by the shape of meniscus curve and particle movement velocity. With considering rheological properties and flow, the resultant chiral film is used to align gold nanorods, and this approach can suggest a way to use M13 bacteriophage as a scaffold for the multi-functional chiral structures.

Printed monolith adsorption as an alternative to expanded bed adsorption for purifying M13 bacteriophage

An ordered 3D printed chromatography stationary phase was used to purify M13 bacteriophage (M13) directly from crude cell culture. This new approach, which offers the same advantages as expanded bed adsorption (EBA) with regard to tolerating solids-laden feed streams but without the corresponding issues associated with fluidized bed stability that affect the latter, can be described as "printed monolith adsorption (PMA)". PMA columns (5, 10 and 15 cm length by 1 cm diameter) were made via a wax templating method from cross-linked cellulose hydrogel and functionalized with a quaternary amine ligand. The recovery of M13 was found to be strongly linked to load flow rate, with the highest recovery 89.7% ± 6% for 1.4 × 10¹¹ pfu/mL of resin occurring at 76 cm/h with a 10 cm column length. A recovery of 87.7% ± 5% for 1.49 × 10¹¹ pfu/mL of media was achieved with a 15 cm column length under conditions comparable to a reported EBA process. The PMA process was completed three times faster than EBA because PMA flow rates can readily be adjusted during operation, with high flow rates and low back pressure, which is unique to the ordered monolithic media geometry used. Equilibration, wash, and cleaning steps were carried out at high flow rates (611 cm/h), minimizing process time and were limited only by the volumetric flow rate capacity of the pumps used, rather than column back pressure (<0.1 MPa at 611 cm/hr). Initial capture of M13 appears to occur on the surface of the monolith solid phase (i.e. the mobile phase channel walls) and subsequently, at a slower rate, within the internal pores of the solid phase media. The difference in binding rate between these two sites is likely caused by slow pore diffusion of the large M13 particles into the pores, with similar slow diffusion out of the pores resulting in tailing of the elution peak. The results indicate that PMA is a promising technology for the efficient purification of viruses directly from crude cell culture.

Multiscale Metal Oxide Particles to Enhance Photocatalytic Antimicrobial Activity against Escherichia coli and M13 Bacteriophage under Dual Ultraviolet Irradiation

Antimicrobial activity of multiscale metal oxide (MO) particles against Escherichia coli (E. coli) and M13 bacteriophage (phage) was investigated under dual ultraviolet (UV) irradiation. Zinc oxide (ZnO), magnesium oxide (MgO), cuprous oxide (Cu₂O), and cupric oxide (CuO) were selected as photocatalytic antimicrobials in MO particles. Physicochemical properties including morphology, particle size/particle size distribution, atomic composition, crystallinity, and porosity were evaluated. Under UV-A and UV-C irradiation with differential UV-C intensities, the antimicrobial activity of MO particles was monitored in E. coli and phage. MO particles had nano-, micro- and nano- to microscale sizes with irregular shapes, composed of atoms as ratios of chemical formulae and presented crystallinity as pure materials. They had wide-range specific surface area levels of 0.40–46.34 m²/g. MO particles themselves showed antibacterial activity against E. coli, which was the highest among the ZnO particles. However, no viral inactivation by MO particles occurred in phage. Under dual UV irradiation, multiscale ZnO and CuO particles had superior antimicrobial activities against E. coli and phage, as mixtures of nano- and microparticles for enhanced photocatalytic antimicrobials. The results showed that the dual UV-multiscale MO particle hybrids exhibit enhanced antibiotic potentials. It can also be applied as a next-generation antibiotic tool in industrial and clinical fields.

Optical bioelectronic nose of outstanding sensitivity and selectivity toward volatile organic compounds implemented with genetically engineered bacteriophage: Integrated study of multi-scale computational prediction and experimental validation

Genetic engineering of a bacteriophage is a promising way to develop a highly functional biosensor. Almost countless configurational degree of freedom in the manipulation, considerable uncertainty and cost involved with the approach, however, have been huddles for the objective. In this paper, we demonstrate rapidly responding optical biosensor with high selectivity toward gaseous explosives with genetically engineered phages. The sensors are equipped with peptide sequences in phages optimally interacting with the volatile organic compounds (VOCs) in visible light regime. To overcome the conventional issues, we use extensive utilization of empirical calculations to construct a large database of 8000 tripeptides and screen the best for electronic nose sensing performance toward nine VOCs belonging to three chemical classes. First-principles density functional theory (DFT) calculations unveil underlying correlations between the chemical affinity and optical property change on an electronic band structure level. The computational outcomes are validated by in vitro experimental design and testing of multiarray sensors using genetically modified phage implemented with five selected tripeptide sequences and wild-type phages. The classification success rates estimated from hierarchical cluster analysis are shown to be very consistent with the calculations. Our optical biosensor demonstrates a 1 ppb level of sensing resolution for explosive VOCs, which is a substantial improvement over conventional biosensor. The systematic interplay of big data-based computational prediction and in situ experimental validation can provide smart design principles for unconventionally outstanding biosensors.

M13 Bacteriophage-Assisted Morphological Engineering of Crack-Based Sensors for Highly Sensitive and Wide Linear Range Strain Sensing

Despite their extraordinary mechanosensitivities, most channel-like crack-based strain sensors are limited by their poor levels of stretchability and linearity. This work presents a simple yet efficient way of modulating the cracking structure of thin metal films on elastomers to facilitate the development of high-performance wearable strain sensors. A net-shaped crack structure based on a thin platinum (Pt) film can be produced by coating an elastomer surface with M13 bacteriophages (phages) and consequently engineering the surface strain upon stretching. This process produces a Pt-on-phage (PoP) strain sensor that simultaneously exhibits high levels of stretchability (24%), sensitivity (maximum gauge factor ≈ 845.6 for 20-24%), and linearity (R² ≈ 0.988 up to 20%). In addition, the sensor performance can be further modulated by either changing the phage coating volume or adding a silver nanowire coating to the PoP sensor film. The balanced strain-sensing performance, combined with fast response times and high levels of mechanical flexibility and operational stability, enables the devices to detect a wide range of human motions in real time after being attached to various body parts. Furthermore, PoP-based strain sensors can be usefully extended to detect more complex multidimensional strains through further strain engineering on a cross-patterned PoP film.

Exhaustive Search of the Receptor Ligands by the CyCLOPS (Cytometry Cell-Labeling Operable Phage Screening) Technique

Effective and versatile screening of the peptide ligands capable of selectively binding to diverse receptors is in high demand for the state-of-the-art technologies in life sciences, including probing of specificity of the cell surface receptors and drug development. Complex microenvironment and structure of the surface receptors significantly reduce the possibility to determine their specificity, especially when in vitro conditions are utilized. Previously, we designed a publicly available platform for the ultra-high-throughput screening (uHTS) of the specificity of surface-exposed receptors of the living eukaryotic cells, which was done by consolidating the phage display and flow cytometry techniques. Here, we significantly improved this methodology and designed the fADL-1e-based phage vectors that do not require a helper hyperphage for the virion assembly. The enhanced screening procedure was tested on soluble human leukocyte antigen (HLA) class II molecules and transgenic antigen-specific B cells that express recombinant lymphoid B-cell receptor (BCR). Our data suggest that the improved vector system may be successfully used for the comprehensive search of the receptor ligands in either cell-based or surface-immobilized assays.

Engineered M13 Peptide Carrier Promotes Angiogenic Potential of Patient-Derived Human Cardiac Progenitor Cells and In Vivo Engraftment

BACKGROUND

Despite promising advances in stem cell-based therapy, the treatment of ischemic cardiovascular diseases remains a big challenge due to both the insufficient in vivo viability of transplanted cells and poor angiogenic potential of stem cells. The goal of this study was to develop therapeutic human cardiac progenitor cells (hCPCs) for ischemic cardiovascular diseases with a novel M13 peptide carrier.

METHOD

In this study, an engineered M13 peptide carrier was successfully generated using a QuikChange Kit. The cellular function of M13 peptide carrier-treated hCPCs was assessed using a tube formation assay and scratch wound healing assay. The in vivo engraftment and cell survival bioactivities of transplanted cells were demonstrated by immunohistochemistry after hCPC transplantation into a myocardial infarction animal model.

RESULTS

The engineered M13^RGD+SDKP peptide carrier, which expressed RGD peptide on PIII site and SDKP peptide on PVIII site, did not affect morphologic change and proliferation ability in hCPCs. In contrast, hCPCs treated with M13^RGD+SDKP showed enhanced angiogenic capacity, including tube formation and migration capacity. Moreover, transplanted hCPCs with M13^RGD+SDKP were engrafted into the ischemic region and promoted in vivo cell survival.

CONCLUSION

Our present data provides a promising protocol for CPC-based cell therapy via short-term cell priming of hCPCs with engineered M13^RGD+SDKP before cell transplantation for treatment of cardiovascular disease.

Accelerated inactivation of M13 bacteriophage using millijoule femtosecond lasers

Irradiation of femtosecond (fs) pulse lasers in the visible and near-infrared ranges have been proposed as a promising approach for inactivating viruses. However, in order to achieve significant virus inactivation, past works have required relatively long irradiation times (1 hour or longer), even for small volumes. Given its advantages compared with other techniques, there is an urgent need to shorten the time required to inactivate viruses using fs laser technology. In this study, we investigate the inactivation of purified M13 bacteriophage in phosphate-buffered saline with large active volume (1 cm³ ), and short exposure time (several minutes), using lasers with 20 mJ/pulse energy at various wavelengths (800, 400 nm or both 800 and 400 nm combined). For an exposure time of 15 and 2 minute, the use of a 400 nm wavelength laser results in a high load reduction of 5.8 ± 0.3 and 2.9 ± 0.15, respectively, on the log₁₀ scale of viability. We show that virus inactivation using the 400 nm laser is much more efficient compared with that using an 800 nm laser, or the simultaneous irradiation of 400 and 800 nm lasers. Higher pathogen inactivation is observed for lasers with shorter pulse duration, whereas at longer pulse durations, the inactivation is reduced. For millijoule-energy fs laser irradiation, the M13 bacteriophage inactivation, via the reduction of the functionality of M13 bacteriophages, is accompanied with relatively small amounts of genetic damage.

Hierarchical Cluster Analysis of Medical Chemicals Detected by a Bacteriophage-Based Colorimetric Sensor Array

M13 bacteriophage-based colorimetric sensors, especially multi-array sensors, have been successfully demonstrated to be a powerful platform for detecting extremely small amounts of target molecules. Colorimetric sensors can be fabricated easily using self-assembly of genetically engineered M13 bacteriophage which incorporates peptide libraries on its surface. However, the ability to discriminate many types of target molecules is still required. In this work, we introduce a statistical method to efficiently analyze a huge amount of numerical results in order to classify various types of target molecules. To enhance the selectivity of M13 bacteriophage-based colorimetric sensors, a multi-array sensor system can be an appropriate platform. On this basis, a pattern-recognizing multi-array biosensor platform was fabricated by integrating three types of sensors in which genetically engineered M13 bacteriophages (wild-, RGD-, and EEEE-type) were utilized as a primary building block. This sensor system was used to analyze a pattern of color change caused by a reaction between the sensor array and external substances, followed by separating the specific target substances by means of hierarchical cluster analysis. The biosensor platform could detect drug contaminants such as hormone drugs (estrogen) and antibiotics. We expect that the proposed biosensor system could be used for the development of a first-analysis kit, which would be inexpensive and easy to supply and could be applied in monitoring the environment and health care.

Recent Developments and Prospects of M13- Bacteriophage Based Piezoelectric Energy Harvesting Devices

Recently, biocompatible energy harvesting devices have received a great deal of attention for biomedical applications. Among various biomaterials, viruses are expected to be very promising biomaterials for the fabrication of functional devices due to their unique characteristics. While other natural biomaterials have limitations in mass-production, low piezoelectric properties, and surface modification, M13 bacteriophages (phages), which is one type of virus, are likely to overcome these issues with their mass-amplification, self-assembled structure, and genetic modification. Based on these advantages, many researchers have started to develop virus-based energy harvesting devices exhibiting superior properties to previous biomaterial-based devices. To enhance the power of these devices, researchers have tried to modify the surface properties of M13 phages, form biomimetic hierarchical structures, control the dipole alignments, and more. These methods for fabricating virus-based energy harvesting devices can form a powerful strategy to develop high-performance biocompatible energy devices for a wide range of practical applications in the future. In this review, we discuss all these issues in detail.

Research Progress of M13 Bacteriophage-Based Biosensors

Recently, new virus-based sensor systems that operate on M13 bacteriophage infrastructure have attracted considerable attention. These systems can detect a range of chemicals with excellent sensitivity and selectivity. Filaments consistent with M13 bacteriophages can be ordered by highly established forms of self-assembly. This allows M13 bacteriophages to build a homogeneous distribution and infiltrate the network structure of nanostructures under mild conditions. Phage display, involving the genetic engineering of M13 bacteriophages, is another strong feature of the M13 bacteriophage as a functional building block. The numerous genetic modification possibilities of M13 bacteriophages are clearly the key features, and far more applications are envisaged. This paper reviews the recent progress in the application of the M13 bacteriophage self-assembly structures through to sensor systems and discusses future M13 bacteriophage technology.

Virus-Templated Nickel Phosphide Nanofoams as Additive-Free, Thin-Film Li-Ion Microbattery Anodes

Transition metal phosphides are a new class of materials generating interest as alternative negative electrodes in lithium-ion batteries. However, metal phosphide syntheses remain underdeveloped in terms of simultaneous control over phase composition and 3D nanostructure. Herein, M13 bacteriophage is employed as a biological scaffold to develop 3D nickel phosphide nanofoams with control over a range of phase compositions and structural elements. Virus-templated Ni₅ P₄ nanofoams are then integrated as thin-film negative electrodes in lithium-ion microbatteries, demonstrating a discharge capacity of 677 mAh g^-1 (677 mAh cm^-3 ) and an 80% capacity retention over more than 100 cycles. This strong electrochemical performance is attributed to the virus-templated, nanostructured morphology, which remains electronically conductive throughout cycling, thereby sidestepping the need for conductive additives. When accounting for the mass of additional binder materials, virus-templated Ni₅ P₄ nanofoams demonstrate the highest practical capacity reported thus far for Ni₅ P₄ electrodes. Looking forward, this synthesis method is generalizable and can enable precise control over the 3D nanostructure and phase composition in other metal phosphides, such as cobalt and copper.

Electric Field Assisted Self-Assembly of Viruses into Colored Thin Films

Filamentous viruses called M13 bacteriophages are promising materials for devices with thin film coatings because phages are functionalizable, and they can self-assemble into smectic helicoidal nanofilament structures. However, the existing “pulling” approach to align the nanofilaments is slow and limits potential commercialization of this technology. This study uses an applied electric field to rapidly align the nanostructures in a fixed droplet. The electric field reduces pinning of the three-phase contact line, allowing it to recede at a constant rate. Atomic force microscopy reveals that the resulting aligned structures resemble those produced via the pulling method. The field-assisted alignment results in concentric color bands quantified with image analysis of red, green, and blue line profiles. The alignment technique shown here could reduce self-assembly time from hours to minutes and lend itself to scalable manufacturing techniques such as inkjet printing.

Mass spectrometry enumeration of filamentous M13 bacteriophage

In the last decade, filamentous M13 bacteriophage has emerged into numerous biotechnological applications as a promising nontoxic and self-assembling biomaterial with specific binding properties. This raises a question about its upscale production that consequently requires an accurate phage enumeration during the various protocol developments. However, traditional methods of measuring phage concentration are mainly biological in nature and therefore time and labor intensive. These traditional methods also demonstrate poor reproducibility and are semi-quantitative at best. In the present work, we capitalized on mass spectrometry based absolute protein quantitation. We have optimized the quantitation conditions for a major coat protein, pVIII. Enumeration of M13 bacteriophage can be further performed using the determined molar concentration of pVIII, Avogadro's number, and known copy number of pVIII per phage. Since many different phages have well-defined copy number of capsid proteins, the proposed approach can be simply applied to any phage with known copy number of a specific capsid protein.

Real-Time Single-Walled Carbon Nanotube-Based Fluorescence Imaging Improves Survival after Debulking Surgery in an Ovarian Cancer Model

Improved cytoreductive surgery for advanced stage ovarian cancer (OC) represents a critical challenge in the treatment of the disease. Optimal debulking reaching no evidence of macroscopic disease is the primary surgical end point with a demonstrated survival advantage. Targeted molecule-based fluorescence imaging offers complete tumor resection down to the microscopic scale. We used a custom-built reflectance/fluorescence imaging system with an orthotopic OC mouse model to both quantify tumor detectability and evaluate the effect of fluorescence image-guided surgery on post-operative survival. The contrast agent is an intraperitoneal injectable nanomolecular probe, composed of single-walled carbon nanotubes, coupled to an M13 bacteriophage carrying a modified peptide binding to the SPARC protein, an extracellular protein overexpressed in OC. The imaging system is capable of detecting a second near-infrared window fluorescence (1000-1700 nm) and can display real-time video imagery to guide intraoperative tumor debulking. We observed high microscopic tumor detection with a pixel-limited resolution of 200 μm. Moreover, in a survival-surgery orthotopic OC mouse model, we demonstrated an increased survival benefit for animals treated with fluorescence image-guided surgical resection compared to standard surgery.

Vertical Self-Assembly of Polarized Phage Nanostructure for Energy Harvesting

Controlling the shape, geometry, density, and orientation of nanomaterials is critical to fabricate functional devices. However, there is limited control over the morphological and directional characteristics of presynthesized nanomaterials, which makes them unsuitable for developing devices for practical applications. Here, we address this challenge by demonstrating vertically aligned and polarized piezoelectric nanostructures from presynthesized biological piezoelectric nanofibers, M13 phage, with control over the orientation, polarization direction, microstructure morphology, and density using genetic engineering and template-assisted self-assembly process. The resulting vertically ordered structures exhibit strong unidirectional polarization with three times higher piezoelectric constant values than that of in-plane aligned structures, supported by second harmonic generation and piezoelectric force microscopy measurements. The resulting vertically self-assembled phage-based piezoelectric energy harvester (PEH) produces up to 2.8 V of potential, 120 nA of current, and 236 nW of power upon 17 N of force. In addition, five phage-based PEH integrated devices produce an output voltage of 12 V and an output current of 300 nA, simply by pressing with a finger. The resulting device can operate light-emitting diode backlights on a liquid crystal display. Our approach will be useful for assembling many other presynthesized nanomaterials into high-performance devices for various applications.

Improvement of High Affinity and Selectivity on Biosensors Using Genetically Engineered Phage by Binding Isotherm Screening

The genetically engineered M13 bacteriophage (M13 phage), developed via directed evolutionary screening process, can improve the sensitivity of sensors because of its selective binding to a target material. Herein, we propose a screening method to develop a selective and sensitive bioreporter for toxic material based on genetically engineered M13 phage. The paraquat (PQ)-binding M13 phage, developed by directed evolution, was used. The binding affinities of the PQ-binding M13 phage to PQ and similar molecules were analyzed using isothermal titration calorimetry (ITC). Based on the isotherms measured by ITC, binding affinities were calculated using the one-site binding model. The binding affinity was 5.161 × 10⁻⁷ for PQ, and 3.043 × 10⁻⁷ for diquat (DQ). The isotherm and raw ITC data show that the PQ-binding M13 phage does not selectively bind to difenzoquat (DIF). The phage biofilter experiment confirmed the ability of PQ-binding M13 bacteriophage to bind PQ. The surface-enhanced Raman scattering (SERS) platform based on the bioreporter, PQ-binding M13 phage, exhibited 3.7 times the signal intensity as compared with the wild-type-M13-phage-coated platform.

Phage-based capacitive biosensor for Salmonella detection

This article reports the detection of Salmonella spp. based on M13 bacteriophage in a capacitive flow injection system. Salmonella-specific M13 bacteriophage was immobilized on a polytyramine/gold surface using glutaraldehyde as a crosslinker. The M13 bacteriophage modified electrode can specifically bind to Salmonella spp. via the amino acid groups on the filamentous phage. An alkaline solution was used to break the binding between the sensing surface and the analyte to allow renewable use up to 40 times. This capacitive system provided good reproducibility with a relative standard deviation (RSD) of 1.1%. A 75 µL min^-1 flow rate and a 300 µL sample volume provided a wide linear range, from 2.0 × 10² to 1.0 × 10⁷ cfu mL^-1, with a detection limit of 200 cfu mL^-1. Bacteria concentration can be analyzed within 40 min after the sample injection. When applied to test real samples (raw chicken meat) it provided good recoveries (100-111%). An enrichment process was also explored to increase the bacteria concentration, enabling a quantitative detection of Salmonella spp. This biosensor opens a new opportunity for the detection of pathogenic bacteria using bacteriophage.

Self-Assembled Nanoporous Biofilms from Functionalized Nanofibrous M13 Bacteriophage

Highly periodic and uniform nanostructures, based on a genetically engineered M13 bacteriophage, displayed unique properties at the nanoscale that have the potential for a variety of applications. In this work, we report a multilayer biofilm with self-assembled nanoporous surfaces involving a nanofiber-like genetically engineered 4E-type M13 bacteriophage, which was fabricated using a simple pulling method. The nanoporous surfaces were effectively formed by using the networking-like structural layers of the M13 bacteriophage during self-assembly. Therefore, an external template was not required. The actual M13 bacteriophage-based fabricated multilayered biofilm with porous nanostructures agreed well with experimental and simulation results. Pores formed in the final layer had a diameter of about 150–500 nm and a depth of about 15–30 nm. We outline a filter application for this multilayered biofilm that enables selected ions to be extracted from a sodium chloride solution. Here, we describe a simple, environmentally friendly, and inexpensive fabrication approach with large-scale production potential. The technique and the multi-layered biofilms produced may be applied to sensor, filter, plasmonics, and bio-mimetic fields.

Ternary Aligned Nanofibers of RGD Peptide-Displaying M13 Bacteriophage/PLGA/Graphene Oxide for Facilitated Myogenesis

Recently, there have been tremendous efforts to develop the biofunctional scaffolds by incorporating various biochemical factors. In the present study, we fabricated poly(lactic-co-glycolic acid) (PLGA) nanofiber sheets decorated with graphene oxide (GO) and RGD peptide. The decoration of GO and RGD peptide was readily achieved by using RGD peptide-displaying M13 bacteriophage (RGD-M13 phage) and electrospinning. Furthermore, the aligned GO-decorated PLGA/RGD peptide (GO-PLGA/RGD) ternary nanofiber sheets were prepared by magnetic field-assisted electrospinning, and their potentials as bifunctional scaffolds for facilitating myogenesis were explored. We characterized the physicochemical and mechanical properties of the sheets by scanning electron microscopy, Raman spectroscopy, contact angle measurement, and tensile test. In addition, the C2C12 skeletal myoblasts were cultured on the aligned GO-PLGA/RGD nanofiber sheets, and their cellular behaviors, including initial attachment, proliferation and myogenic differentiation, were evaluated. Our results revealed that the GO-PLGA/RGD nanofiber sheets had suitable physicochemical and mechanical properties for supporting cell growth, and could significantly promote the spontaneous myogenic differentiation of C2C12 skeletal myoblasts. Moreover, it was revealed that the myogenic differentiation was further accelerated on the aligned GO-PLGA/RGD nanofiber sheets due to the synergistic effects of RGD peptide, GO and aligned nanofiber structure. Therefore, , it is suggested that the aligned GO-PLGA/RGD ternary nanofiber sheets are one of the most promising approaches for facilitating myogenesis and promoting skeletal tissue regeneration.

Engineering of M13 Bacteriophage for Development of Tissue Engineering Materials

M13 bacteriophages have several qualities that make them attractive candidates as building blocks for tissue regenerating scaffold materials. Through genetic engineering, a high density of functional peptides and proteins can be simultaneously displayed on the M13 bacteriophage's outer coat proteins. The resulting phage can self-assemble into nanofibrous network structures and can guide the tissue morphogenesis through proliferation, differentiation and apoptosis. In this manuscript, we will describe methods to develop major coat-engineered M13 phages as a basic building block and aligned tissue-like matrices to develop regenerative nanomaterials.

Dual UV irradiation-based metal oxide nanoparticles for enhanced antimicrobial activity in Escherichia coli and M13 bacteriophage

Metal oxide (MO) nanoparticles have been studied as nano-antibiotics due to their antimicrobial activities even in antibiotic-resistant microorganisms. We hypothesized that a hybrid system of dual UV irradiation and MO nanoparticles would have enhanced antimicrobial activities compared with UV or MO nanoparticles alone. In this study, nanoparticles of ZnO, ZnTiO₃, MgO, and CuO were selected as model nanoparticles. A dual UV collimated beam device of UV-A and UV-C was developed depending upon the lamp divided by coating. Physicochemical properties of MO nanoparticles were determined using powder X-ray diffractometry (PXRD), Brunauer-Emmett-Teller analysis, and field emission-scanning electron microscopy with energy-dispersive X-ray spectroscopy. Atomic force microscopy with an electrostatic force microscopy mode was used to confirm the surface topology and electrostatic characteristics after dual UV irradiation. For antimicrobial activity test, MO nanoparticles under dual UV irradiation were applied to Escherichia coli and M13 bacteriophage (phage). The UV-A and UV-C showed differential intensities in the coated and uncoated areas (UV-A, coated = uncoated; UV-C, coated ≪ uncoated). MO nanoparticles showed sharp peaks in PXRD patterns, matched to pure materials. Their primary particle sizes were less than 100 nm with irregular shapes, which had an 8.6~25.6 m²/g of specific surface area with mesopores of 22~262 nm. The electrostatic properties of MO nanoparticles were modulated after UV irradiation. ZnO, MgO, and CuO nanoparticles, except ZnTiO₃ nanoparticles, showed antibacterial effects on E. coli. Antimicrobial effects on E. coli and phages were also enhanced after cyclic exposure of dual UV and MO nanoparticle treatment using the uncoated area, except ZnO nanoparticles. Our results demonstrate that dual UV-MO nanoparticle hybrid system has a potential for disinfection. We anticipate that it can be developed as a next-generation disinfection system in pharmaceutical industries and water purification systems.

Rod-Like Virus-Based Multiarm Colloidal Molecules

We report on the construction of multiarm colloidal molecules by tip-linking filamentous bacteriophages, functionalized either by biological engineering or chemical conjugation. The affinity for streptavidin of a genetically modified vector phage displaying Strep-tags fused to one end of the viral particle is measured by determining the dissociation constant, K_d. In order to improve both the colloidal stability and the efficiency of the self-assembly process, a biotinylation protocol having a chemical yield higher than 90% is presented to regioselectively functionalize the cystein residues located at one end of the bacteriophages. For both viral systems, a theoretical comparison is performed by developing a quantitative model of the self-assembly and interaction of the modified viruses with streptavidin compounds, which accurately accounts for our experimental results. Multiarm colloidal structures of different valencies are then produced by conjugation of these tip-functionalized viruses with streptavidin activated nanoparticles. We succeed to form stable virus-based colloidal molecules, whose number of arms, called valency, is solely controlled by tuning the molar excess. Thanks to a fluorescent labeling of the viral arms, the dynamics of such systems is also presented in real time by fluorescence microscopy.

Engineered M13 Nanofiber Accelerates Ischemic Neovascularization by Enhancing Endothelial Progenitor Cells

Dysfunction or loss of blood vessel causes several ischemic diseases. Although endothelial progenitor cells (EPCs) are a promising source for cell-based therapy, ischemia-induced pathophysiological condition limits the recovery rate by causing drastic cell death. To overcome this issue, we attempted to develop a cell-targeted peptide delivery and priming system to enhance EPC-based neovascularization using an engineered M13 bacteriophage harboring nanofibrous tubes displaying ~2700 multiple functional motifs. The M13 nanofiber was modified by displaying RGD, which is an integrin-docking peptide, on the minor coat protein, and by mutilayering SDKP motifs, which are the key active sites for thymosin β4, on the major coat protein. The engineered M13 nanofiber dramatically enhanced ischemic neovascularization by activating intracellular and extracellular processes such as proliferation, migration, and tube formation in the EPCs. Furthermore, transplantation of the primed EPCs with the M13 nanofiber harboring RGD and SDKP facilitated functional recovery and neovascularization in a murine hindlimb ischemia model. Overall, this study demonstrates the effectiveness of the M13 nanofiber-based novel peptide delivery and priming strategy in promoting EPC bioactivity and neovessel regeneration. To our knowledge, this is first report on M13 nanofibers harboring dual functional motifs, the use of which might be a novel strategy for stem and progenitor cell therapy against cardiovascular ischemic diseases.

Phage-Based Structural Color Sensors and Their Pattern Recognition Sensing System

The mammalian olfactory system provides great inspiration for the design of intelligent sensors. To this end, we have developed a bioinspired phage nanostructure-based color sensor array and a smartphone-based sensing network system. Using a M13 bacteriophage (phage) as a basic building block, we created structural color matrices that are composed of liquid-crystalline bundled nanofibers from self-assembled phages. The phages were engineered to express cross-responsive receptors on their major coat protein (pVIII), leading to rapid, detectable color changes upon exposure to various target chemicals, resulting in chemical- and concentration-dependent color fingerprints. Using these sensors, we have successfully detected 5-90% relative humidity with 0.2% sensitivity. In addition, after modification with aromatic receptors, we were able to distinguish between various structurally similar toxic chemicals including benzene, toluene, xylene, and aniline. Furthermore, we have developed a method of interpreting and disseminating results from these sensors using smartphones to establish a wireless system. Our phage-based sensor system has the potential to be very useful in improving national security and monitoring the environment and human health.

Recent advances in M13 bacteriophage-based optical sensing applications

Recently, M13 bacteriophage has started to be widely used as a functional nanomaterial for various electrical, chemical, or optical applications, such as battery components, photovoltaic cells, sensors, and optics. In addition, the use of M13 bacteriophage has expanded into novel research, such as exciton transporting. In these applications, the versatility of M13 phage is a result of its nontoxic, self-assembling, and specific binding properties. For these reasons, M13 phage is the most powerful candidate as a receptor for transducing chemical or optical phenomena of various analytes into electrical or optical signal. In this review, we will overview the recent progress in optical sensing applications of M13 phage. The structural and functional characters of M13 phage will be described and the recent results in optical sensing application using fluorescence, surface plasmon resonance, Förster resonance energy transfer, and surface enhanced Raman scattering will be outlined.

Simulation of the M13 life cycle I: Assembly of a genetically-structured deterministic chemical kinetic simulation

To expand the quantitative, systems level understanding and foster the expansion of the biotechnological applications of the filamentous bacteriophage M13, we have unified the accumulated quantitative information on M13 biology into a genetically-structured, experimentally-based computational simulation of the entire phage life cycle. The deterministic chemical kinetic simulation explicitly includes the molecular details of DNA replication, mRNA transcription, protein translation and particle assembly, as well as the competing protein-protein and protein-nucleic acid interactions that control the timing and extent of phage production. The simulation reproduces the holistic behavior of M13, closely matching experimentally reported values of the intracellular levels of phage species and the timing of events in the M13 life cycle. The computational model provides a quantitative description of phage biology, highlights gaps in the present understanding of M13, and offers a framework for exploring alternative mechanisms of regulation in the context of the complete M13 life cycle.

Simulation of the M13 life cycle II: Investigation of the control mechanisms of M13 infection and establishment of the carrier state

Bacteriophage M13 is a true parasite of bacteria, able to co-opt the infected cell and control the production of progeny across many cellular generations. Here, our genetically-structured simulation of M13 is applied to quantitatively dissect the interplay between the host cellular environment and the controlling interactions governing the phage life cycle during the initial establishment of infection and across multiple cell generations. Multiple simulations suggest that phage-encoded feedback interactions constrain the utilization of host DNA polymerase, RNA polymerase and ribosomes. The simulation reveals the importance of p5 translational attenuation in controlling the production of phage double-stranded DNA and suggests an underappreciated role for p5 translational self-attenuation in resource allocation. The control elements active in a single generation are sufficient to reproduce the experimentally-observed multigenerational curing of the phage infection. Understanding the subtleties of regulation will be important for maximally exploiting M13 particles as scaffolds for nanoscale devices.

Gold-Coated M13 Bacteriophage as a Template for Glucose Oxidase Biofuel Cells with Direct Electron Transfer

Glucose oxidase-based biofuel cells are a promising source of alternative energy for small device applications, but still face the challenge of achieving robust electrical contact between the redox enzymes and the current collector. This paper reports on the design of an electrode consisting of glucose oxidase covalently attached to gold nanoparticles that are assembled onto a genetically engineered M13 bacteriophage using EDC-NHS chemistry. The engineered phage is modified at the pIII protein to attach onto a gold substrate and serves as a high-surface-area template. The resulting "nanomesh" architecture exhibits direct electron transfer (DET) and achieves a higher peak current per unit area of 1.2 mA/cm(2) compared to most other DET attachment schemes. The final enzyme surface coverage on the electrode was calculated to be approximately 4.74 × 10(-8) mol/cm(2), which is a significant improvement over most current glucose oxidase (GOx) DET attachment methods.

Application of an M13 bacteriophage displaying tyrosine on the surface for detection of Fe(3+) and Fe(2+) ions

Ferric and ferrous ion plays critical roles in bioprocesses, their influences in many fields have not been fully explored due to the lack of methods for quantification of ferric and ferrous ions in biological system or complex matrix. In this study, an M13 bacteriophage (phage) was engineered for use as a sensor for ferric and ferrous ions via the display of a tyrosine residue on the P8 coat protein. The interaction between the specific phenol group of tyrosine and Fe(3+) / Fe(2+) was used as the sensor. Transmission electron microscopy showed aggregation of the tyrosine-displaying phages after incubation with Fe(3+) and Fe(2+). The aggregated phages infected the host bacterium inefficiently. This phenomenon could be utilized for detection of ferric and ferrous ions. For ferric ions, a calibration curve ranging from 200 nmol/L to 8 μmol/L with a detection limit of 58 nmol/L was acquired. For ferrous ions, a calibration curve ranging from 800 nmol/L to 8 μmol/L with a detection limit of 641.7 nmol/L was acquired. The assay was specific for Fe(3+) and Fe(2+) when tested against Ni(2+), Pb(2+), Zn(2+), Mn(2+), Co(2+), Ca(2+), Cu(2+), Cr(3+), Ba(2+), and K(+). The tyrosine displaying phage to Fe(3+) and Fe(2+) interaction would have plenty of room in application to biomaterials and bionanotechnology.

Direct detection and measurement of wall shear stress using a filamentous bio-nanoparticle

The wall shear stress (WSS) that a moving fluid exerts on a surface affects many processes including those relating to vascular function. WSS plays an important role in normal physiology (e.g. angiogenesis) and affects the microvasculature's primary function of molecular transport. Points of fluctuating WSS show abnormalities in a number of diseases; however, there is no established technique for measuring WSS directly in physiological systems. All current methods rely on estimates obtained from measured velocity gradients in bulk flow data. In this work, we report a nanosensor that can directly measure WSS in microfluidic chambers with sub-micron spatial resolution by using a specific type of virus, the bacteriophage M13, which has been fluorescently labeled and anchored to a surface. It is demonstrated that the nanosensor can be calibrated and adapted for biological tissue, revealing WSS in micro-domains of cells that cannot be calculated accurately from bulk flow measurements. This method lends itself to a platform applicable to many applications in biology and microfluidics.