M13 Virus-Incorporated Biotemplates on Electrode Surfaces To Nucleate Metal Nanostructures by Electrodeposition

Self-assembly of Au@AgNR along M13 framework: A SERS nanocarrier for bacterial detection and killing

Self-assembled functional nanomaterials with electromagnetic hot spots are crucial and highly desirable in surface-enhanced Raman scattering (SERS). Due to its versatile biological scaffold, the M13 phage has been employed to produce novel nano-building blocks and devices. In this study, we propose a novel M13 phage-based SERS nanocarrier, that utilizes the pVIII capsid in M13 to conjugate Au@Ag core-shell nanorod (Au@AgNR) with linker carboxy-PEG-thiol (M13-Au@AgNR) and the pIII capsid to specifically target Escherichia coli (E. coli). The M13-Au@AgNR@DTTC (3,3'- diethylthiocarbocyanine iodide) SERS probe was used to detect E. coli in a concentration range of 6 to 6 × 105 cfu/mL, achieving a limit of detection (LOD) of 0.5 cfu/mL. The proposed SERS platform was also tested in real samples, showing good recoveries (92%-114.3%) and a relative standard deviation (RSD) of 1.2%-4.7%. Furthermore, the system demonstrated high antibacterial efficiency against E. coli, approximately 90%, as measured by the standard plate-count method. The investigation provides an effective strategy for in vitro bacteria detection and inactivation.

Electrochemical aptasensor based on electrodeposited poly(3,4-ethylenedioxythiophene)-graphene oxide coupled with Au@Pt nanocrystals for the detection of 17β-estradiol

An electrochemical aptasensor is reported for the sensitive and specific monitoring of 17β-estradiol (E2) based on the modification of electrodeposited poly(3,4-ethylenedioxythiophene) (PEDOT)-graphene oxide (GO) coupled with Au@Pt nanocrystals (Au@Pt). With excellent conductivity, chemical stability and active sites, the PEDOT-GO nanocomposite film was firstly in situ polymerized on the glassy carbon electrode by cyclic voltammetry. Subsequently, one-step synthesized Au@Pt were decorated on the conductive polymer, providing a platform for immobilizing the aptamer and enhancing the detecting sensitivity. With the addition of E2, since the interfacial electron transfer process was retarded by the E2-aptamer complex, the differential pulse voltammetry signal decreased gradually. Under optimum conditions, the calibration curve of E2 exhibited a linear range between 0.1 pM and 1 nM, with a low detection limit (S/N = 3) of 0.08 pM. The developed aptasensor showed admiring selectivity, stability, and reproducibility. It was tested in human serum, lake water and tap water samples after low-cost and simple pretreatment. Consequently, the developed platform could provide a new design thought for ultrasensitive detection of E2 in clinical and environmental samples.

Recent advances in the synthesis and applications of graphene-polypeptide nanocomposites

The combination of peptides and graphene-derived materials provides a new way to prepare graphene-based nanocomposites with unique structures, properties, and functions. The modification of graphene with different polypeptides not only improves the biocompatibility and biological recognition ability of graphene-based materials, but also greatly expands their application fields. In this work, we summarize different interactions between graphene and polypeptides, and the synthesis methods of novel functional graphene-polypeptide nanocomposites based on the interactions in recent years (from 2016 to present). In addition, the potential applications of graphene-peptide hybrid nanocomposites in biomedicine, tissue engineering, biosensors, environmental science engineering, optoelectronic materials, and energy storage are introduced. We hope that this review will help readers to understand the methods and mechanisms of the modification of graphene surfaces with biomolecules, and promote readers to understand the synthesis and applications of graphene-based nanocomposites. This work may provide hints and references for the development of peptide sequence design, and biomedical and functional materials, and will help in designing and synthesizing novel graphene-based nanomaterials with unique properties and suitable for various applications in the future.

Prospects in interfaces of biomolecule DNA and nanomaterials as an effective way for improvising surface enhanced Raman scattering: A review

Surface Enhanced Raman Scattering (SERS) is a field of research that has shown promising application in the analysis of various substrate molecules by means of rough metallic surfaces. In directing the enhancement of substrate molecules in micro and nano-molar concentrations, plasmonic coupling of metal nanoparticles (NPs), morphology of metal NPs and the closely arrangement of rough metal surfaces that produces 'hot spots' can effectively increase the so-called enhancement factor (EF) that will be applicable in various fields. As the mechanistic aspects are still not clear, research has been triggered all over the world for the past two decades to have a clear understanding in chemical and electromagnetic effects. As the reproducibility of intensity of signals at low concentrations of probe molecules is of a big concern, metal NPs with various scaffolds were prepared and recently bio-molecule, DNA has been studied and showed promising advantages. This review first time highlights metal NPs with DNA interface as an effective rough metallic surface for SERS with high intensity and also with better reproducibility. Based on this review, similar kinds of scaffolds like DNA can be used to further analyze SERS activities of various metal NPs with different morphologies to have high intense signals at low concentrations of probe molecules.

Determination and characterisation of the surface charge properties of the bacteriophage M13 to assist bio-nanoengineering

To truly understand the mechanisms behind the supramolecular self-assembly of nanocomponents, the characterisation of their surface properties is crucial. M13 emerged as a practical nanocomponent for bio-nanoassemblies of functional materials and devices, and its popularity is increasing as time goes by. The investigation performed in this study provides important information about the surface charge and the surface area of M13 determined through the comparison of structural data and the measurement of ζ-potential at pH ranging between 2 and 11. The developed methodologies along with the experimental findings can be subsequently exploited as a novel and convenient prediction tool of the total charge of modified versions of M13. This, in turn, will facilitate the design of the self-assembly strategies which would combine the virus building block with other micro and nano components via intermolecular interactions.

Three-dimensional assembly of silver nanoparticles spatially confined by cellular structure of Spirulina, from nanospheres to nanosheets

Three-dimensional (3D) ordered construction of nanoparticles (NPs) has attracted much attention in wide applications, however, techniques with respect to cost effective nanofabrication of well defined functional architectures is still lacking. To address this specific issue, a bio-interface confinement approach is proposed that precisely replicates the complex cellular structural features of microbes and integrates silver NP (SNP) building blocks into their 3D framework in a precise, low cost and mass production way. Herein, the SNPs with nanospheres and nanosheets structure were synthesized by way of electroless deposition using Spirulina as template. Results showed that SNPs were orderly assembled along the cellular structure, and the spatially confinement of cellular texture induced the transformation of SNPs from sphere to flake morphology during their continuous growth. The silver assembly not only shows good antibacterial activity, but also exhibits excellent surface enhanced Raman scattering (SERS) performance with the enhancement factor as high as 5.95 × 10⁸ and good recuperability towards Rhodamine 6G. The fascinating SERS performance can be ascribed to the combined action of nanosheets morphology of SNPs, hierarchical nanostructure of the cellular structure, and the small interparticle spacing. This strategy provides an effective strategy for controllable and ordered 3D assembly of NPs by using the cellular texture.

Electrodeposition of AuPt Alloy Nanostructures on a Biotemplate with Hierarchically Assembled M13 Virus Film Used for Methanol Oxidation Reaction

Herein, we report an electrode surface with a hierarchical assembly of wild-type M13 virus nanofibers (M13) to nucleate the AuPt alloy nanostructures by electrodeposition. M13 was pulled on the electrode surface to produce a virus film, and then a layer of sol–gel matrix (SSG) was wrapped over the surface to protect the film, thereby a bio-template was constructed. Blending of metal binding domains of M13 and amine groups of the SSG of the bio-template were effectively nucleate and directed the growth of nanostructures (NSs) such as Au, Pt and AuPt alloy onto the modified electrode surface by electrodeposition. An electrocatalytic activity of the modified electrode toward methanol oxidation in alkaline medium was investigated and found an enhanced mass activity (534 mA/mgPt) relative to its controlled experiments. This bio-templated growth of NSs with precise composition could expedite the intention of new alloy materials with tuneable properties and will have efficacy in green energy, catalytic, and energy storage applications.

Competitive electrochemical immunosensor for maduramicin detection by multiple signal amplification strategy via hemin@Fe-MIL-88NH2/AuPt

Maduramicin (MD) is a type of monoglycoside polyether ionophore antibiotic that can effectively treat coccidiosis and facilitate animal growth. However, its extensive and excessive use brings potential risk to human health. Herein, an electrochemical immunosensor based on indirect competitive format was fabricated for analysis of MD residue in eggs by a multiple signal amplification system. Initially, Au nanoparticles were deposited onto glassy carbon electrode surface to load the coating antigen MD-BSA and to improve conductivity. Then the signal amplification platform was constructed by encapsulating hemin into Fe-MIL-88 NH₂ metal-organic frameworks (hemin@MOFs), and then the obtained composites were decorated with AuPt nanoparticles. The synthesized hemin@MOFs/AuPt was not only used as a signal amplification mediator, but also utilized as a carrier for immobilization of horseradish peroxidase-conjugated affinipure goat anti-mouse antibody (Ab₂-HRP) and horseradish peroxidase (HRP). The constructed hemin@MOFs/AuPt-Ab₂-HRP bioconjugates could effectively amplify the current signal since hemin@MOFs, AuPt and HRP all exhibited high catalytic activity towards the hydrogen peroxide. Moreover, the established immunosensor showed high sensitivity and stability during the detection procedure. With the synergistic catalytic effect of hemin@MOFs, AuPt and HRP, a wide detection range of 0.1-50 ng mL^-1 and a low detection limit of 0.045 ng mL^-1 were achieved (S/N = 3), respectively. Ultimately, the developed method displayed excellent performance in practical applications, providing a promising probability to detect other veterinary drug residues to guarantee food safety.

A signal-decreased electrochemical immunosensor for the sensitive detection of LAG-3 protein based on a hollow nanobox-MOFs/AuPt alloy

In this work, hollow nanobox metal-organic framework (HNM) nanocomposites were synthesised and utilised for the first time in a signal decreased electrochemical immunosensor for the ultrasensitive quantitative determination of lymphocyte activation gene-3 (LAG-3) protein, which is a newly discovered biomarker. With the aid of signal materials, namely, SiO₂-tagged anti-LAG-3 antibody (SiO₂-Ab₂) and the biotin-streptavidin system, the sensor can achieve signal amplification. Encapsulation of tin dioxide-functionalised reduced graphene oxide (rGO-SnO₂) and gold and platinum alloys (AuPt alloys) onto the surface of hollow nanobox metal-organic frameworks (MOFs) was performed to prepare rGO-SnO₂/hollow nanobox-MOFs/AuPt alloys (rGO-SnO₂/HNMs/AuPt) as the matrix. SiO₂-Ab₂, which is used as the signal-decreased label, can be utilised to enhance the distinction of the electrochemical signal after the specific recognition between antibodies and antigens, owing to its large steric hindrance property. In this sensor, this proposed sandwich immunosensor can achieve a high sensitivity, especially in the presence of low concentrations of the LAG-3 protein. Under optimal conditions, this sandwich-designed immunosensor exhibited a sensitive detection of the LAG-3 protein from concentrations of 0.01 ng mL^-1 to 1 μg mL^-1, with a lower detection limit of 1.1 pg mL^-1 (based on 3σ). We proposed that this ultrasensitive biosensor can be utilised for the detection of the LAG-3 protein in early clinical tumour diagnosis.

Phage-Based Applications in Synthetic Biology

Bacteriophage research has been instrumental to advancing many fields of biology, such as genetics, molecular biology, and synthetic biology. Many phage-derived technologies have been adapted for building gene circuits to program biological systems. Phages also exhibit significant medical potential as antibacterial agents and bacterial diagnostics due to their extreme specificity for their host, and our growing ability to engineer them further enhances this potential. Phages have also been used as scaffolds for genetically programmable biomaterials that have highly tunable properties. Furthermore, phages are central to powerful directed evolution platforms, which are being leveraged to enhance existing biological functions and even produce new ones. In this review, we discuss recent examples of how phage research is influencing these next-generation biotechnologies.

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.