Peptide interactions with metal and oxide surfaces

Identification of Pathogenic Missense Mutations of NF1 Using Computational Approaches

Neurofibromatosis type 1 (NF1) is a prevalent autosomal dominant disorder caused by mutations in the NF1 gene, leading to multisystem disorders. Given the critical role of cysteine residues in protein stability and function, we aimed to identify key NF1 mutations affecting cysteine residues that significantly contribute to neurofibromatosis pathology. To identify the most critical mutations in the NF1 gene that contribute to the pathology of neurofibromatosis, we employed a sophisticated computational pipeline specifically designed to detect significant mutations affecting the NF1 gene. Our approach involved an exhaustive search of databases such as the Human Gene Mutation Database (HGMD), UniProt, and ClinVar for information on missense mutations associated with NF1. Our search yielded a total of 204 unique cysteine missense mutations. We then employed in silico prediction tools, including PredictSNP, iStable, and Align GVGD, to assess the impact of these mutations. Among the mutations, C379R, R1000C, and C1016Y stood out due to their deleterious effects on the biophysical properties of the neurofibromin protein, significantly destabilizing its structure. These mutations were subjected to further phenotyping analysis using SNPeffect 4.0, which predicted disturbances in the protein's chaperone binding sites and overall structural stability. Furthermore, to directly visualize the impact of these mutations on protein structure, we utilized AlphaFold3 to simulate both the wild-type and mutant NF1 structures, revealing the significant effects of the R1000C mutation on the protein's conformation. In conclusion, the identification of these mutations can play a pivotal role in advancing the field of precision medicine and aid in the development of effective drugs for associated diseases.

Dependence of lactose adsorption on the exposed crystal facets of metals: a comparative study of gold, silver and copper

In this theoretical work, we investigated the adsorption of a lactose molecule on metal-based surfaces, with a focus on the influence of the nature of the metal and of the type of exposed crystal facet on the adsorbed structures and energetics. More precisely, we considered three flat crystallographic facets of three face-centered cubic metals (gold, silver, and copper). For the global exploration of the energy landscape, we employed a multi-stage procedure where high-throughput searches, using a stochastic method that performs global optimization by iterating local searches, are followed by a refinement of the most probable adsorption conformations of the molecule at the ab initio level. We predicted the optimal conformation of lactose on each of the nine metal-surface combinations, classified the many low-energy minima into possible adsorption modes, and analyzed the structural, electronic and energetic aspects of the lactose molecule on the surface, as well as their dependence on the type of metal and exposed crystal facet. We observed structural similarities between the various minimum-energy conformations of lactose in vacuum and on the surface, a rough correlation between adsorption and interaction energies of the molecule, and a small charge transfer between molecule and surface whose direction is metal-dependent. During adsorption, an electronic reorganization occurs at the metal-molecule interface only, without affecting the vacuum-pointing atoms of the lactose molecule. For all types of surfaces, lactose exhibits the weakest adsorption on silver substrates, while for each coinage metal the adsorption is strongest on the (110) crystal facet. This study demonstrates that the control of exposed facets can allow to modulate the interaction between metals and small saccharides.

Surface Chemistry of Biologically Active Reducible Oxide Nanozymes

Reducible metal oxide nanozymes (rNZs) are a subject of intense recent interest due to their catalytic nature, ease of synthesis, and complex surface character. Such materials contain surface sites which facilitate enzyme-mimetic reactions via substrate coordination and redox cycling. Further, these surface reactive sites are shown to be highly sensitive to stresses within the nanomaterial lattice, the physicochemical environment, and to processing conditions occurring as part of their syntheses. When administered in vivo, a complex protein corona binds to the surface, redefining its biological identity and subsequent interactions within the biological system. Catalytic activities of rNZs each deliver a differing impact on protein corona formation, its composition, and in turn, their recognition, and internalization by host cells. Improving the understanding of the precise principles that dominate rNZ surface-biomolecule adsorption raises the question of whether designer rNZs can be engineered to prevent corona formation, or indeed to produce "custom" protein coronas applied either in vitro, and preadministration, or formed immediately upon their exposure to body fluids. Here, fundamental surface chemistry processes and their implications in rNZ material performance are considered. In particular, material structures which inform component adsorption from the application environment, including substrates for enzyme-mimetic reactions are discussed.

Noble Metal Nanoparticles with Nanogel Coatings: Coinage Metal Thiolate-Stabilized Glutathione Hydrogel Shells

Developing biocompatible nanocoatings is crucial for biomedical applications. Noble metal colloidal nanoparticles with biomolecular shells are thought to combine diverse chemical and optothermal functionalities with biocompatibility. Herein, we present nanoparticles with peptide hydrogel shells that feature an unusual combination of properties: the metal core possesses localized plasmon resonance, whereas a few-nanometer-thick shells open opportunities to employ their soft framework for loading and scaffolding. We demonstrate this concept with gold and silver nanoparticles capped by glutathione peptides stacked into parallel β-sheets as they aggregate on the surface. A key role in the formation of the ordered structure is played by coinage metal(I) thiolates, i.e., Ag(I), Cu(I), and Au(I). The shell thickness can be controlled via the concentration of either metal ions or peptides. Theoretical modeling of the shell's molecular structure suggests that the thiolates have a similar conformation for all the metals and that the parallel β-sheet-like structure is a kinetic product of the peptide aggregation. Using third-order nonlinear two-dimensional infrared spectroscopy, we revealed that the ordered secondary structure is similar to the bulk hydrogels of the coinage metal thiolates of glutathione, which also consist of aggregated stacked parallel β-sheets. We expect that nanoparticles with hydrogel shells will be useful additions to the nanomaterial toolbox. The present method of nanogel coating can be applied to arbitrary surfaces where the initial deposition of the seed glutathione monolayer is possible.

Peptide-functionalized zinc oxide nanoparticles for the selective targeting of breast cancer expressing placenta-specific protein 1

Functionalized metal oxide nanoparticles (NPs) have demonstrated specific binding affinity to antigens or receptors presented on the cancer cell surface, favouring selective targeting and minimizing side effects during the chemotherapy. Placenta-specific protein 1 (PLAC-1) is a small cell surface protein overexpressed in certain types of breast cancer (BC); therefore, it can be used as a therapeutic target. The objective of this study is to develop NPs that can bind PLAC-1 and hence can inhibit the progression and metastatic potential of BC cells. Zinc oxide (ZnO) NPs were coated with a peptide (GILGFVFTL), which possesses a strong binding ability to PLAC-1. The physical attachment of the peptide to ZnO NPs was verified through various physicochemical and morphological characterization techniques. The selective cytotoxicity of the designed NPs was investigated using PLAC-1-bearing MDA-MB 231 human BC cell line and compared to LS-180 cells that do not express PLAC-1. The anti-metastatic and pro-apoptotic effects of the functionalized NPs on MDA-MB 231 cells were examined. Confocal microscopy was used to investigate the mechanism of NPs uptake by MDA-MB 231 cells. Compared to non-functionalized NPs, peptide functionalization significantly improved the targeting and uptake of the designed NPs by PLAC-1-expressing cancer cells with significant pro-apoptotic and anti-metastatic effects. The uptake of peptide functionalized ZnO NPs (ZnO-P NPs) occurred via peptide-PLAC1 interaction-assisted clathrin-mediated endocytosis. These findings highlight the potential targeted therapy of ZnO-P NPs against PLAC-1-expressing breast cancer cells.

Oxide- and Silicate-Water Interfaces and Their Roles in Technology and the Environment

Interfacial reactions drive all elemental cycling on Earth and play pivotal roles in human activities such as agriculture, water purification, energy production and storage, environmental contaminant remediation, and nuclear waste repository management. The onset of the 21st century marked the beginning of a more detailed understanding of mineral aqueous interfaces enabled by advances in techniques that use tunable high-flux focused ultrafast laser and X-ray sources to provide near-atomic measurement resolution, as well as by nanofabrication approaches that enable transmission electron microscopy in a liquid cell. This leap into atomic- and nanometer-scale measurements has uncovered scale-dependent phenomena whose reaction thermodynamics, kinetics, and pathways deviate from previous observations made on larger systems. A second key advance is new experimental evidence for what scientists hypothesized but could not test previously, namely, interfacial chemical reactions are frequently driven by "anomalies" or "non-idealities" such as defects, nanoconfinement, and other nontypical chemical structures. Third, progress in computational chemistry has yielded new insights that allow a move beyond simple schematics, leading to a molecular model of these complex interfaces. In combination with surface-sensitive measurements, we have gained knowledge of the interfacial structure and dynamics, including the underlying solid surface and the immediately adjacent water and aqueous ions, enabling a better definition of what constitutes the oxide- and silicate-water interfaces. This critical review discusses how science progresses from understanding ideal solid-water interfaces to more realistic systems, focusing on accomplishments in the last 20 years and identifying challenges and future opportunities for the community to address. We anticipate that the next 20 years will focus on understanding and predicting dynamic transient and reactive structures over greater spatial and temporal ranges as well as systems of greater structural and chemical complexity. Closer collaborations of theoretical and experimental experts across disciplines will continue to be critical to achieving this great aspiration.

Nucleotide Interaction with Nanocrystalline Ceria Surface

The adsorption of nucleotides on the surface of nanocrystalline cerium dioxide (pHpzc = 6.3) in NaCl solutions was investigated using multi-batch adsorption experiments over a wide range of pH. The obtained results were interpreted as a formation of outer and inner sphere surface complexes with the participation of phosphate moieties. The Basic Stern surface complexation model was applied to obtain quantitative equilibrium reaction constants.

Peptide Nanosheet-Inspired Biomimetic Synthesis of CuS Nanoparticles on Ti3C2 Nanosheets for Electrochemical Biosensing of Hydrogen Peroxide

Hydrogen peroxide (H₂O₂) is one of the intermediates or final products of biological metabolism and participates in many important biological processes of life activities. The detection of H₂O₂ is of great significance in clinical disease monitoring, environmental protection, and bioanalysis. In this study, Ti₃C₂-based nanohybrids are prepared by the biological modification and self-assembled peptide nanosheets (PNSs)-based biomimetic synthesis of copper sulfide nanoparticles (CuS NPs), which show potential application in the fabrication of low-cost and high-performance electrochemical H₂O₂ biosensors. The synthesized CuS-PNSs/Ti₃C₂ nanohybrids exhibit excellent electrochemical performance towards H₂O₂, in which CuS NPs can catalyze the decomposition of H₂O₂ and realize the transformation from a chemical signal to an electrical signal to achieve the purpose of H₂O₂ detection. The prepared CuS-PNSs/Ti₃C₂-based electrochemical biosensor platform exhibits a wide detection range (5 μM-15 mM) and a low detection limit (0.226 μM). In addition, it reveals good selectivity and stability and can realize the monitoring of H₂O₂ in a complex environment. The successful biomimetic synthesis of CuS-PNSs/Ti₃C₂ hybrid nanomaterials provides a green and friendly strategy for the design and synthesis of functional nanomaterials and also provides a new inspiration for the construction of highly effective electrochemical biosensors for practical detection of H₂O₂ in various environments.

Coordination Chemistry of Uranyl Ions with Surface-Immobilized Peptides: An XPS Study

The coordination chemistry of uranyl ions with surface immobilized peptides was studied using X-ray photoemission spectroscopy (XPS). All the peptides in the study were modified using a six-carbon alkanethiol as a linker on a gold substrate with methylene blue as the redox label. The X-ray photoemission spectra reveal that each modified peptide interacts differently with the uranyl ion. For all the modified peptides, the XPS spectra were taken in both the absence and presence of the uranium, and their comparison reveals that the interaction depends on the chemical group present in the peptides. The XPS results show that, among all the modified peptides in the current study, the (arginine)₉ (R9) modified peptide showed the largest response to uranium. In the order of response to uranium, the second largest response was shown by the modified (arginine)₆ (R6) peptide followed by the modified (lysine)₆ (K6) peptide. Other modified peptides, (alanine)₆ (A6), (glutamic acid)₆ (E6) and (serine)₆ (S6), did not show any response to uranium.

Peptide adsorption on silica surfaces: Simulation and experimental insights

The understanding of interactions between proteins with silica surface is crucial for a wide range of different applications: from medical devices, drug delivery and bioelectronics to biotechnology and downstream processing. We show the application of EISM (Effective Implicit Surface Model) for discovering the set of peptide interactions with silica surface. The EISM is employed for a high-speed computational screening of peptides to model the binding affinity of small peptides to silica surfaces. The simulations are complemented with experimental data of peptides with silica nanoparticles from microscale thermophoresis and from infrared spectroscopy. The experimental work shows excellent agreement with computational results and verifies the EISM model for the prediction of peptide-surface interactions. 57 peptides, with amino acids favorable for adsorption on Silica surface, are screened by EISM model for obtaining results, which are worth to be considered as a guidance for future experimental and theoretical works. This model can be used as a broad platform for multiple challenges at surfaces which can be applied for multiple surfaces and biomolecules beyond silica and peptides.

Leucine on Silica: A Combined Experimental and Modeling Study of a System Relevant for Origins of Life, and the Role of Water Coadsorption

Leucine on silica constitutes an interesting system from the point of view of origins of life studies since leucine coadsorbed on SiO₂ together with glutamic acid can give rise to rather long linear polypeptides upon activation. It is also an ideal system to test methods of molecular characterization of biomolecules deposited on mineral surfaces since it combines a small-scale model of peptides and proteins, which are among the most important components of biodevices, with one of the most widely used inorganic materials. We have deposited l-leucine on a high surface fumed silica in the submonolayer range and characterized it by a multipronged approach including macroscopic information (thermogravimetry, X-ray diffraction), in situ spectroscopic methods (IR, multinuclear solid-state NMR including single-pulse and CP-MAS, 2-D HETCOR), and molecular modeling by density functional theory (DFT), including calculation of NMR parameters. Specific information can be obtained on the adsorption and interaction mechanism. Leucine is rather strongly adsorbed without any covalent bonds, through the formation of a specific lattice of H-bonds that often involve coadsorbed water molecules. Its state is indeed strongly dependent on the drying procedure: insufficient drying results in liquid-like surroundings for the leucine functional groups, while vacuum drying only retains a limited number of waters (of the order of 5 per leucine molecule). The most stable models have zwitterionic leucine interacting directly with surface silanols through their ammonium group, while the carboxylate interacts through bridging waters. Experimental NMR chemical shifts are satisfactorily predicted for these models, and leucine can be viewed as a probe for specific groups of surface sites known as silanol nests.

The Impact of the Surface Modification on Tin-Doped Indium Oxide Nanocomposite Properties

This review provides an analysis of the theoretical methods to study the effects of surface modification on structural properties of nanostructured indium tin oxide (ITO), mainly by organic compounds. The computational data are compared with experimental data such as X-ray diffraction (XRD), atomic force microscopy (AFM) and energy-dispersive X-ray spectroscopy (EDS) data with the focus on optoelectronic and electrocatalytic properties of the surface to investigate potential relations of these properties and applications of ITO in fields such as biosensing and electronic device fabrication. Our analysis shows that the change in optoelectronic properties of the surface is mainly due to functionalizing the surface with organic molecules and that the electrocatalytic properties vary as a function of size.

Peptide sequence-driven direct electron transfer properties and binding behaviors of gold-binding peptide-fused glucose dehydrogenase on electrode

Oriented enzyme immobilization on electrodes is crucial for interfacial electrical coupling of direct electron transfer (DET)-based enzyme-electrode systems. As inorganic-binding peptides are introduced as molecular binders and enzyme-orienting agents, inorganic-binding peptide-fused enzymes should be designed and constructed to achieve efficient DET. In this study, it is aimed to compare the effects of various gold-binding peptides (GBPs) fused to enzymes on electrocatalytic activity, bioactivity, and material-binding behaviors. Here, GBPs with identical gold-binding properties but different amino acid sequences were fused to the FAD-dependent glucose dehydrogenase gamma-alpha complex (GDHγα) to generate four GDHγα variants. The structural, biochemical, mechanical, and bioelectrochemical properties of these GDHγα variants immobilized on electrode were determined by their fused GBPs. Our results confirmed that the GBP type is vital in the design, construction, and optimization of GBP-fused enzyme-modified electrodes for facile interfacial DET and practical DET-based enzyme-electrode systems.

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The four GBP sequences are genetically fused to catalytic subunit of GDHγα complex

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The cofactor-surface interface was investigated with 3D models of fusion enzymes

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The four systems exhibit diverse electrochemical results depending on GBP type

X-ray photoemission studies of the interaction of metals and metal ions with DNA

X-ray Photoelectron Spectroscopy (XPS) has been used to study the interactions of heavy metal ions with DNA with some success. Surface sensitivity and selectivity of XPS are advantageous for identifying and characterizing the chemical and elemental structure of the DNA to metal interaction. This review summarizes the status of what amounts to a large part of the photoemission investigations of biomolecule interactions with metals and offers insight into the mechanism for heavy metal-bio interface interactions. Specifically, it is seen that metal interaction with DNA results in conformational changes in the DNA structure.

Critical Review: Role of Inorganic Nanoparticle Properties on Their Foliar Uptake and in Planta Translocation

There is increasing pressure on global agricultural systems due to higher food demand, climate change, and environmental concerns. The design of nanostructures is proposed as one of the economically viable technological solutions that can make agrochemical use (fertilizers and pesticides) more efficient through reduced runoff, increased foliar uptake and bioavailability, and decreased environmental impacts. However, gaps in knowledge about the transport of nanoparticles across the leaf surface and their behavior in planta limit the rational design of nanoparticles for foliar delivery with controlled fate and limited risk. Here, the current literature on nano-objects deposited on leaves is reviewed. The different possible foliar routes of uptake (stomata, cuticle, trichomes, hydathodes, necrotic spots) are discussed, along with the paths of translocation, via the phloem, from the leaf to the end sinks (mature and developing tissues, roots, rhizosphere). This review details the interplays between morphological constraints, environmental stimuli, and physical-chemical properties of nanoparticles influencing their fate, transformation, and transport after foliar deposition. A metadata analysis from the existing literature highlighted that plant used for testing nanoparticle fate are most often dicotyledon plants (75%), while monocotyledons (as cereals) are less considered. Correlations on parameters calculated from the literature indicated that nanoparticle dose, size, zeta potential, and affinity to organic phases correlated with leaf-to-sink translocation, demonstrating that targeting nanoparticles to specific plant compartments by design should be achievable. Correlations also showed that time and plant growth seemed to be drivers for in planta mobility, parameters that are largely overlooked in the literature. This review thus highlights the material design opportunities and the knowledge gaps for targeted, stimuli driven deliveries of safe nanomaterials for agriculture.

Probing Adsorption of Dipeptides on Anatase in H2 O and D2 O: Thermodynamics and Molecular Geometry

Considering the vast importance of peptide and protein interactions with inorganic surfaces, probing hydrogen bonding during their adsorption on metal oxide surfaces is a relevant task that could shed light on the essential features of their interplay. This work is devoted to studying the dipeptides' adsorption on anatase nanoparticles (ANs) in light and heavy water to reveal differences arising upon the change of the major hydrogen bonding carrier. Thermodynamic study of six native dipeptides' adsorption on ANs in both media shows a strong influence of the solvent on the Gibbs free energy and the effect of side-chain mobile protons on the entropy of the process. The adsorption is endothermic irrespective of the medium and is entropy-driven. Computer simulations of peptide adsorption in both media shows similarity in binding via an amino group and demonstrates structural features of protonated and deuterated peptides in obtained complexes. Calculated peptide- anatase nanoparticle (AN) descriptors indicate surface oxygens as points of peptide-nanoparticle contacts.

Synthesis of near-infrared absorbing triangular Au nanoplates using biomineralisation peptides

Triangular Au nanoplates (TrAuNPls) possessing strong plasmonic properties can be used as photothermal agents in cancer therapy. However, the controlled preparation of such morphologies typically requires harsh synthetic conditions. Biomolecules offer an alternative route to developing biocompatible synthetic protocols. In particular, peptides offer a novel route for inorganic synthesis under ambient conditions. Herein, using the previously isolated peptide, ASHQWAWKWE, for Au nanoparticle (AuNP) synthesis, the conditions for preparing TrAuNPls via a one-pot synthetic process of mixing HAuCl₄ and peptides at room temperature were investigated to effectively obtain particles possessing near-infrared absorbance for non-invasive optical diagnosis and phototherapy. By adjusting the peptide concentration, the size and property of TrAuNPls were controlled under neutral pH conditions. The synthesised particles showed potential as photothermal therapeutic agents in vitro. In addition, peptide characterisation using B3 derivatives revealed the importance of the third amino acid histidine in morphological regulation and potential circular Au nanoplates (AuNPl) synthesis with ASEQWAWKWE and ASAQWAWKWE peptides. These findings provide not only an easy and green synthetic method for TrAuNPls and circular AuNPls, but also some insight to help elucidate the regulation of peptide-based nanoparticle synthesis for use in cancer therapy. STATEMENT OF SIGNIFICANCE: Biological molecules have received increasing attention as a vehicle to synthesise inorganic materials with specific properties under ambient conditions; particularly, short peptides have the potential to control the synthesis of nanoscale materials with tailored functions. Here, the application of a previously isolated peptide was assessed in synthesising Au nanoparticles containing decahedral and triangular nanoplates with near-infrared absorbance. The size and absorbance peaks of the triangular nanoplates observed were peptide concentration-dependent. In addition, these fine-tuned triangular nanoplates exhibited potential as a phototherapeutic agent. Moreover, the peptide derivatives indicated the possibility of synthesising circular nanoplates. These findings may offer insight into development of new techniques for synthesising functional nanoparticles having biological applications using non-toxic molecules under mild conditions stituted in the original B3 peptide is underlined.

Chirality in peptide-based materials: From chirality effects to potential applications

Chirality is ubiquitous in nature with primary cellular functions that include construction of right-/left-handed helix and selective communications among diverse biomolecules. Of particularly intriguing are the chiral peptide-based materials that can be deliberately designed to change physicochemistry properties via tuning peptide sequences. Critically, understanding their chiral effects are fundamental for the development of novel materials in chemistry and biomedicine fields. Here, we review recent researches on chirality in peptide-based materials, summarizing relevant typical chiral effects towards recognition, amplification, and induction. Driven forces for the chiral discrimination in affinity interaction as well as the handedness preferences in supramolecular structure formation at both the macroscale and microscale are illustrated. The implementation of such chirality effects of artificial copolymers, assembled aggregates and their composites in the fields of bioseparation and bioenrichment, cell incubation, protein aggregation inhibitors, chiral smart gels, and bionic electro devices are also presented. At last, the challenges in these areas and possible directions are pointed out. The diversity of chiral roles in the origin of life and chirality design in different organic or composite systems as well as their applications in drug development and chirality detection in environmental protection are discussed.

A minimalistic cyclic ice-binding peptide from phage display

Developing molecules that emulate the properties of naturally occurring ice-binding proteins (IBPs) is a daunting challenge. Rather than relying on the (limited) existing structure-property relationships that have been established for IBPs, here we report the use of phage display for the identification of short peptide mimics of IBPs. To this end, an ice-affinity selection protocol is developed, which enables the selection of a cyclic ice-binding peptide containing just 14 amino acids. Mutational analysis identifies three residues, Asp8, Thr10 and Thr14, which are found to be essential for ice binding. Molecular dynamics simulations reveal that the side chain of Thr10 hydrophobically binds to ice revealing a potential mechanism. To demonstrate the biotechnological potential of this peptide, it is expressed as a fusion ('Ice-Tag') with mCherry and used to purify proteins directly from cell lysate.

Interaction of cyclosporin A molecules with alkali and transition metal atoms on Cu(111)

The structure of a cyclic peptide with important biological functionalities, cyclosporin A (CsA), is investigated at the single molecule level. Its adsorption on Cu(111) under ultra-high vacuum is characterised with scanning tunnelling microscopy (STM) and density functional theory. With STM investigations, we demonstrate element specific on-surface coordination schemes of CsA with coadsorbed K, Co and Fe atoms. Thus, clear insights emerge in the behaviour of cyclic peptides at interfaces and their interactions with different metal atoms, providing control of the adsorption structure and assembly and paving the way for the integration of cyclic peptides in functional metal-organic nanostructures on surfaces.

Bacteriophage Capsid Modification by Genetic and Chemical Methods

Bacteriophages are viruses whose ubiquity in nature and remarkable specificity to their host bacteria enable an impressive and growing field of tunable biotechnologies in agriculture and public health. Bacteriophage capsids, which house and protect their nucleic acids, have been modified with a range of functionalities (e.g., fluorophores, nanoparticles, antigens, drugs) to suit their final application. Functional groups naturally present on bacteriophage capsids can be used for electrostatic adsorption or bioconjugation, but their impermanence and poor specificity can lead to inconsistencies in coverage and function. To overcome these limitations, researchers have explored both genetic and chemical modifications to enable strong, specific bonds between phage capsids and their target conjugates. Genetic modification methods involve introducing genes for alternative amino acids, peptides, or protein sequences into either the bacteriophage genomes or capsid genes on host plasmids to facilitate recombinant phage generation. Chemical modification methods rely on reacting functional groups present on the capsid with activated conjugates under the appropriate solution pH and salt conditions. This review surveys the current state-of-the-art in both genetic and chemical bacteriophage capsid modification methodologies, identifies major strengths and weaknesses of methods, and discusses areas of research needed to propel bacteriophage technology in development of biosensors, vaccines, therapeutics, and nanocarriers.

Insights into colloidal nanoparticle-protein corona interactions for nanomedicine applications

Colloidal nanoparticles (NPs) have attracted significant attention due to their unique physicochemical properties suitable for diagnosing and treating different human diseases. Nevertheless, the successful implementation of NPs in medicine demands a proper understanding of their interactions with the different proteins found in biological fluids. Once introduced into the body, NPs are covered by a protein corona (PC) that determines the biological behavior of the NPs. The formation of the PC can eventually favor the rapid clearance of the NPs from the body before fulfilling the desired objective or lead to increased cytotoxicity. The PC nature varies as a function of the different repulsive and attractive forces that govern the NP-protein interaction and their colloidal stability. This review focuses on the phenomenon of PC formation on NPs from a physicochemical perspective, aiming to provide a general overview of this critical process. Main issues related to NP toxicity and clearance from the body as a result of protein adsorption are covered, including the most promising strategies to control PC formation and, thereby, ensure the successful application of NPs in nanomedicine.

A whole area scanning-enabled direct-counting strategy for studying blocking efficiency in mitigating protein-solid surface binding

The study of protein-solid surface binding as well as blocking efficiency of blocking agents plays an important role in the development of high-performance immunoassays. Although conventional colorimetric based assays are widely employed to monitor protein non-specific binding on the surface of microplate wells and evaluate the performance of blocking agents, there is still a great need to develop new methods to achieve the same goal from a new perspective. In this study, an innovative whole area scanning (WAS)-enabled direct-counting strategy was developed and validated through studying the blocking efficiency of different blocking agents on the non-specific binding of streptavidin-alkaline phosphatase conjugate (Strep-ALP, a model protein) to the surface of 96-well microplates. After non-specific binding of Strep-ALP in wells with or without blocking agents' treatment and loading of ELF™ 97 phosphate (ELFP), ALP in Strep-ALP conjugates converts ELFP to water-insoluble ELF™ 97 alcohol (ELFA), which precipitates locally, self-assembles into large needle structures, and glows green fluorescence upon excitation. After quenching the reaction, WAS of the whole wells allows us to directly count the number of individual fluorescent precipitates, which can be used to calculate and compare the blocking efficiency of three commonly used blocking agents (BSA, casein, and dry milk) based on mitigating the non-specific binding of Strep-ALP. WAS-enabled counting of individual needle-type precipitates opens a new avenue to investigate protein-solid surface binding as well as the efficiency of blocking agents with high sensitivity.

Chemogenetic engineering of nitrobindin toward an artificial epoxygenase

Chemogenetic engineering turned the heme protein nitrobindin into an artificial epoxygenase: MnPPIX was introduced and subsequent protein engineering increased the activity in the epoxidation of styrene derivatives by overall 7-fold.

A new nanometrological strategy for titanium dioxide nanoparticles screening and confirmation in personal care products by CE-spICP-MS

A new nanometrological approach was developed for screening of titania nanoparticles by capillary electrophoresis after adsorption of a target analyte namely l-cysteine onto the nanoparticles in a sodium phosphate buffer, followed by titanium elemental analysis by means of inductively-coupled plasma-mass spectrometry and size distribution measurements by single-particle mode. This analytical strategy involved a first screening of nanotitania in actual samples by electrophoresis, sensitivity being enhanced by cysteine which acts as a nanoparticles stabiliser. Detection and quantitation limits were 0.31 ng μL^-1 and 1.03 ng μL^-1 respectively for anatase nanoparticles in capillary electrophoresis, and a high amount of titanium was found in the samples subject to study (lip balm and two types of toothpaste) by total elemental analysis. Besides, the potential of single-particle modality for inductively-coupled plasma-mass spectrometry was exploited for a verification of particle size distribution, then confirming the presence of titanium dioxide nanoparticles as an ingredient in the composition of the real samples and validating the overall strategy herein presented.

Studies of Dynamic Binding of Amino Acids to TiO2 Nanoparticle Surfaces by Solution NMR and Molecular Dynamics Simulations

Adsorption of biomolecules onto material surfaces involves a potentially complex mechanism where molecular species interact to varying degrees with a heterogeneous material surface. Surface adsorption studies by atomic force microscopy, sum frequency generation spectroscopy, and solid-state NMR detect the structures and interactions of biomolecular species that are bound to material surfaces, which, in the absence of a solid-liquid interface, do not exchange rapidly between surface-bound forms and free molecular species in bulk solution. Solution NMR has the potential to complement these techniques by detecting and studying transiently bound biomolecules at the liquid-solid interface. Herein, we show that dark-state exchange saturation transfer (DEST) NMR experiments on gel-stabilized TiO₂ nanoparticle (NP) samples detect several forms of biomolecular adsorption onto titanium(IV) oxide surfaces. Specifically, we use the DEST approach to study the interaction of amino acids arginine (Arg), lysine (Lys), leucine (Leu), alanine (Ala), and aspartic acid (Asp) with TiO₂ rutile NP surfaces. Whereas Leu, Ala, and Asp display only a single weakly interacting form in the presence of TiO₂ NPs, Arg and Lys displayed at least two distinct bound forms: a species that is surface bound and retains a degree of reorientational motion and a second more tightly bound form characterized by broadened DEST profiles upon the addition of TiO₂ NPs. Molecular dynamics simulations indicate different surface bound states for both Lys and Arg depending on the degree of TiO₂ surface hydroxylation but only a single bound state for Asp regardless of the degree of surface hydroxylation, in agreement with results obtained from the analysis of DEST profiles.

Selective modification of Ti6Al4V surfaces for biomedical applications

The surface of a medical implant is required to interact favourably with ions, biomolecules and cells in vivo, commonly resulting in the formation of the extracellular matrix. Medical grade Ti6Al4V alloy is widely used in orthopaedic and dental applications for bone replacement due to its advantageous mechanical properties and biocompatibility, which enhances the adhesion between native tissue and the implanted material. In this study, chemical and thermal modification of a medical-grade Ti6Al4V alloy were performed to enhance electrostatic interactions at the alloy surface with a synthetic peptide, suitable for conferring drug release capabilities and antimicrobial properties. The modified surfaces exhibited a range of topographies and chemical compositions depending primarily on the treatment temperature. The surface wetting behaviour was found to be pH-dependent, as were the adhesive properties, evidenced by chemical force titration atomic force microscopy.

The design and development of short peptide-based novel smart materials to prevent fouling by the formation of non-toxic and biocompatible coatings

Biofouling refers to the undesirable process that leads to the accumulation of microorganisms such as bacteria or fungi on substrates. This is one of the major concerns associated with several components of our regular life such as food, health, water and energy. In the healthcare sector, biofouling on medical devices is known to cause infections, which are often resistant to conventional antibiotics and lead to increase in the number of hospital and surgery-related deaths. One of the better ways to tackle the problem of biofouling is the development of smart antifouling materials that can produce a biocompatible, non-toxic, eco-friendly and functional coating and maintain a biological environment without any adverse effect. To this end, in the present study, we have reported the design and synthesis of two simple chemically modified peptides, namely, PA1 (PFB-VVD) and PA2 (PFB-LLE). The design as well as the amino acid sequence of the peptides contains three basic components that enable their ability to (i) self-assemble into functional coatings, (ii) bind with the desired surface via the bi-dentate coordination of dicarboxylate groups and (iii) exhibit antifouling activity and generate a non-toxic biocompatible supramolecular coating on the desired surface. PA1 having aspartic acid as the anchoring moiety exhibits better antifouling activity compared to PA2 that has glutamic acid as the anchoring moiety. This is probably due to the greater adhesive force or binding affinity of aspartic acid to the examined surface compared to that of glutamic acid, as confirmed by force measurement studies using AFM. Most importantly, the simple drop-coating method promises great advantages due to its ease of operation, which leads to a reduction in the production cost and increase in the scope of commercialization. To the best of our knowledge, this is the first attempt to develop an ultra-short peptide-based smart antifouling material with a dicarboxylate group as the surface binding moiety. Furthermore, these findings promise to provide further insights into antifouling mechanisms in the future by the development of a smart material using a dicarboxylate group as an anchoring moiety.

Array-Based Screening of Silver Nanoparticle Mineralization Peptides

The use of biomolecules in nanomaterial synthesis has received increasing attention, because they can function as a medium to produce inorganic materials in ambient conditions. Short peptides are putative ligands that interact with metallic surfaces, as they have the potential to control the synthesis of nanoscale materials. Silver nanoparticle (AgNP) mineralization using peptides has been investigated; however, further comprehensive analysis must be carried out, because the design of peptide mediated-AgNP properties is still highly challenging. Herein, we employed an array comprising 200 spot synthesis-based peptides, which were previously isolated as gold nanoparticle (AuNP)-binding and/or mineralization peptides, and the AgNP mineralization activity of each peptide was broadly evaluated. Among 10 peptides showing the highest AgNP-synthesis activity (TOP10), nine showed the presence of EE and E[X]E (E: glutamic acid, and X: any amino acid), whereas none of these motifs were found in the WORST25 (25 peptides showing the lowest AgNP synthesis activity) peptides. The size and morphology of the particles synthesized by TOP3 peptides were dependent on their sequences. These results suggested not only that array-based techniques are effective for the peptide screening of AgNP mineralization, but also that AgNP mineralization regulated by peptides has the potential for the synthesis of AgNPs, with controlled morphology in environmentally friendly conditions.

Peptide Nanotube-Templated Biomineralization of Cu2-x S Nanoparticles for Combination Treatment of Metastatic Tumor

1D peptide nanostructures (i.e., peptide nanotubes, PNTs) exhibit tunable chemo-physical properties and functions such as improved tissue adhesion, increased cellular uptake, and elongated blood circulation. In this study, the application of PNTs as a desirable 1D template for biomineralization of Cu_2-x S nanoparticles (Cu_2-x S NPs, x = 1-2) is reported. Monodisperse Cu_2-x S NPs are uniformly coated on the peptide nanotubes owing to the specific high binding affinity of Cu ions to the imidazole groups exposed on the surface of nanotubes. The Cu_2-x S NP-coated PNTs are further covalently grafted with an oxaliplatin prodrug (Pt-CuS-PNTs) to construct a versatile nanoplatform for combination cancer therapy. Upon 808 nm laser illumination, the nanoplatform induces significant hyperthermia effect and elicits reactive oxygen species generation through electron transfer and Fenton-like reaction. It is demonstrated that the versatile nanoplatform dramatically inhibits tumor growth and lung metastasis of melanoma in a B16-F10 melanoma tumor-bearing mouse model by combined photo- and chemotherapy. This study highlights the ability of PNTs for biomineralization of metal ions and the promising potential of such nanoplatforms for cancer treatment.

Systematic modification of the indium tin oxide work function via side-chain modulation of an amino-acid functionalization layer

Controlled modification of the semiconductor surface work function is of fundamental importance for improvements in the efficiency of (opto-)electronic devices. Binding amino acids to a semiconductor surface through their common carboxylic group offers a versatile tool for modulation of surface properties by the choice of their side chain. This approach is demonstrated here by tailoring the surface work function of indium tin oxide, one of the most abundant transparent electrodes in organic optoelectronic devices. We find that the work function can be systematically tuned by the side chain of the amino acid, resulting in either an increase or a decrease of the work function, over a large range of ∼250 meV. This side chain effect is mostly due to alteration of the dipole component perpendicular to the surface, with a generally smaller contribution for changes in surface band bending. These findings also shed light on electronic interactions at the interface between proteins and semiconductors, which are of importance for future bio-electronic devices.

Directed evolution of artificial repeat proteins as habit modifiers for the morphosynthesis of (111)-terminated gold nanocrystals

Natural biocomposites are shaped by proteins that have evolved to interact with inorganic materials. Protein directed evolution methods which mimic Darwinian evolution have proven highly successful to generate improved enzymes or therapeutic antibodies but have rarely been used to evolve protein-material interactions. Indeed, most reported studies have focused on short peptides and a wide range of oligopeptides with chemical binding affinity for inorganic materials have been uncovered by phage display methods. However, their small size and flexible unfolded structure prevent them from dictating the shape and crystallinity of the growing material. In the present work, a specific set of artificial repeat proteins (αRep), which exhibit highly stable 3D folding with a well-defined hypervariable interacting surface, is selected by directed evolution of a very efficient home-built protein library for their high and selective affinity for the Au(111) surface. The proteins are built from the extendable concatenation of self-compatible repeated motifs idealized from natural HEAT proteins. The high-yield synthesis of Au(111)-faceted nanostructures mediated by these αRep proteins demonstrates their chemical affinity and structural selectivity that endow them with high crystal habit modification performances. Importantly, we further exploit the protein shell spontaneously assembled on the nanocrystal facets to drive protein-mediated colloidal self-assembly and on-surface enzymatic catalysis. Our method constitutes a generic tool for producing nanocrystals with determined faceting, superior biocompatibility and versatile bio-functionalization towards plasmon-based devices and (bio)molecular sensors.

Rational Design of Iron Oxide Binding Peptide Tags

Owing to their extraordinary magnetic properties and low-cost production, iron oxide nanoparticles (IONs) are in the focus of research. In order to better understand interactions of IONs with biomolecules, a tool for the prediction of the propensity of different peptides to interact with IONs is of great value. We present an effective implicit surface model (EISM), which includes several interaction models. Electrostatic interactions, van der Waals interactions, and entropic effects are considered for the theoretical calculations. However, the most important parameter, a surface accessible area force field contribution term, derives directly from experimental results on the interactions of IONs and peptides. Data from binding experiments of ION agglomerates to different peptides immobilized on cellulose membranes have been used to parameterize the model. The work was carried out under defined environmental conditions; hence, effects because of changes, for example structure or solubility by changing the surroundings, are not included. EISM enables researchers to predict the binding of peptides to IONs, which we then verify with further peptide array experiments in an iterative optimization process also presented here. Negatively charged peptides were identified as best binders for IONs in Tris buffer. Furthermore, we investigated the constitution of peptides and how the amount and position of several amino acid side chains affect peptide-binding. The incorporation of glycine leads to higher binding scores compared to the incorporation of cysteine in negatively charged peptides.

Two-Dimensional Infrared Spectroscopy Reveals Molecular Self-Assembly on the Surface of Silver Nanoparticles

The conformation of molecules, peptides, and proteins, self-assembled into structured monolayers on the surface of metal nanoparticles (NPs), can strongly affect their properties and use in chemical or nanobiomedical applications. Elucidating molecular conformations on the NP surface is highly challenging, and the microscopic details mostly remain elusive. Using polarization-selective third-order two-dimensional ultrafast infrared spectroscopy, we revealed the highly ordered intermolecular structure of γ-tripeptide glutathione on the surface of silver NPs in aqueous solution. Glutathione is an antioxidant thiol abundant in living cells; it is extensively used in NP chemistry and related research. We identified conditions where the interaction of glutathione with the NP surface facilitates formation of a β-sheet-like structure enclosing the NPs. A spectroscopic signature associated with the assembly of β-sheets into an amyloid fibril-like structure was also observed. Remarkably, the interaction with the metal surface promotes formation of a fibril-like structure by a small peptide involving only two amino acids.

Surface Complexation Modeling of Biomolecule Adsorptions onto Titania

The adsorption of nucleic acid components on the surface of nanocrystalline titaniumdioxide (anatase, pH_pzc = 6.5) in NaCl solutions was investigated using potentiometric titrationsand multibatch adsorption experiments over a wide range of pH and ionic strengths. The BasicStern surface complexation model was applied to experimental data to obtain quantitativeequilibrium reaction constants. Adsorption results suggest that there is a considerable difference inthe binding of nucleobases, nucleosides, and nucleotides with an anatase surface.

Effect of calcium ions on peptide adsorption at the aqueous rutile titania (110) interface

How the presence of Ca²⁺ ions at the aqueous TiO₂ interface influences the binding modes of two experimentally identified titania-binding peptides, Ti-1 and Ti-2, is investigated using replica exchange with solute tempering molecular dynamics simulations. The findings are compared with available experimental data, and the results are contrasted with those obtained under NaCl solution conditions. For Ti-1, Ca²⁺ ions enhance the adsorption of the negatively charged Asp8 residue in this sequence to the negatively charged surface, via Asp–Ca²⁺–TiO₂ bridging. This appears to generate a nonlocal impact on the adsorption of Lys12 in Ti-1, which then pins the peptide to the surface via direct surface contact. For Ti-2, fewer residues were predicted to adsorb directly to the surface in CaCl₂, compared with predictions made for NaCl solution, possibly due to competition between the other peptide residues and Ca²⁺ ions to adsorb to the surface. This reduction in direct surface contact gives rise to a more extensive solvent-mediated contact for Ti-2. In general, the presence of Ca²⁺ ions resulted in a loss of conformational diversity of the surface-adsorbed conformational ensembles of these peptides, compared to counterpart data predicted for NaCl solution. The findings provide initial insights into how peptide–TiO₂ interactions might be tuned at the molecular level via modification of the salt composition of the liquid medium.

L-Phenylalanine-Templated Platinum Catalyst with Enhanced Performance for Oxygen Reduction Reaction

Pt-based materials are the most efficient catalysts for the oxygen reduction reaction (ORR) in proton-exchange membrane fuel cells. However, fabrication of active and stable Pt catalysts still remains challenging. In this work, Pt-l-phenylalanine (Pt-LPHE) films, with highly dispersed Pt nanoparticles (NPs) featuring predominately (111) facets, have been prepared via a room-temperature electron reduction method. Loading Pt-LPHE onto carbon support produces a novel nanomaterial (Pt-AL/C), resulting in a simultaneous loading of highly dispersed Pt NPs and N doping. Density functional theory calculations demonstrate that the N dopants stabilize the Pt NPs and reduce the *O/*OH binding energies on the Pt NPs. As a result, the Pt-AL/C nanomaterial shows significantly enhanced ORR activity and stability over commercial Pt/C after 10 000 cycle stability tests. This work provides a novel eco-friendly and energy-neutral approach for preparing metal NPs with controllable structures and sizes.

Polarization-Dependent Atomic Force Microscopy-Infrared Spectroscopy (AFM-IR): Infrared Nanopolarimetric Analysis of Structure and Anisotropy of Thin Films and Surfaces

Infrared techniques enable nondestructive and label-free studies of thin films with high chemical and structural contrast. In this work, we review recent progress and perspectives in the nanoscale analysis of anisotropic materials using an extended version of the atomic force microscopy-infrared (AFM-IR) technique. This advanced photothermal technique, includes polarization control of the incoming light and bridges the gap in IR spectroscopic analysis of local anisotropic material properties. Such local anisotropy occurs in a wide range of materials during molecular nucleation, aggregation, and crystallization processes. However, analysis of the anisotropy in morphology and structure can be experimentally and theoretically demanding as it is related to order and disorder processes in ranges from nanoscopic to macroscopic length scales, depending on preparation and environmental conditions. In this context IR techniques can significantly assist as IR spectra can be interpreted in the framework of optical models and numerical calculations with respect to both, the present chemical conditions as well as the micro- and nanostructure. With these extraordinary analytic possibilities, the advanced AFM-IR approach is an essential puzzle piece in direction to connect nanoscale and macroscale anisotropic thin film properties experimentally. In this review, we highlight the analytic possibilities of AFM-IR for studies on nanoscale anisotropy with a set of examples for polymer, plasmonic, and polaritonic films, as well as aggregates of large molecules and proteins.

Magnetic Nanoparticles Conjugated with Peptides Derived from Monocyte Chemoattractant Protein-1 as a Tool for Targeting Atherosclerosis

Atherosclerosis is a multifactorial inflammatory disease that may progress silently for long period, and it is also widely accepted as the main cause of cardiovascular diseases. To prevent atherosclerotic plaques from generating, imaging early molecular markers and quantifying the extent of disease progression are desired. During inflammation, circulating monocytes leave the bloodstream and migrate into incipient lipid accumulation in the artery wall, following conditioning by local growth factors and proinflammatory cytokines; therefore, monocyte accumulation in the arterial wall can be observed in fatty streaks, rupture-prone plaques, and experimental atherosclerosis. In this work, we synthesized monocyte-targeting iron oxide magnetic nanoparticles (MNPs), which were incorporated with the peptides derived from the chemokine receptor C-C chemokine receptor type 2 (CCR2)-binding motif of monocytes chemoattractant protein-1 (MCP-1) as a diagnostic tool for potential atherosclerosis. MCP-1-motif MNPs co-localized with monocytes in in vitro fluorescence imaging. In addition, with MNPs injection in ApoE knockout mice (ApoE KO mice), the well-characterized animal model of atherosclerosis, MNPs were found in specific organs or regions which had monocytes accumulation, especially the aorta of atherosclerosis model mice, through in vivo imaging system (IVIS) imaging and magnetic resonance imaging (MRI). We also performed Oil Red O staining and Prussian Blue staining to confirm the co-localization of MCP-1-motif MNPs and atherosclerosis. The results showed the promising potential of MCP-1-motif MNPs as a diagnostic agent of atherosclerosis.

Mechanisms of Enhanced Hemoglobin Electroactivity on Carbon Electrodes upon Exposure to a Water-Miscible Primary Alcohol

Exposing a carbon electrode to hemoglobin (Hb) and alcoholic solvents, such as methanol, ethanol or 1-propanol, drastically changes Hb electroactivity, but until this work, the important underlying mechanisms were unclear. For the first time, we show that these alcohols impact Hb electroactivity via three mechanisms: modification of the carbon surface oxides on the glassy carbon (GC) electrode, Hb film formation, and structural changes to Hb. C_1s X-ray photoelectron spectroscopy provided evidence for significant alcohol-induced modification of the carbon surface oxides, and differential pulse voltammetry showed links between these modifications and Hb electroactivity. Spectroscopic ellipsometry showed that Hb films formed during exposure to Hb- and alcohol-containing electrolytes increased in thickness with increasing alcohol content, although film thickness played only a minor role in Hb electroactivity. Alcohol-induced structural changes in Hb are confirmed with UV-visible absorption and fluorescence data, showing that Hb denaturation also was a significant factor in increasing Hb electroactivity. Carbon-surface-oxide modification and Hb denaturation worked in tandem to maximally increase the Hb electroactivity in 60% methanol. While in ethanol and 1-propanol, the significant increases in Hb electroactivity caused by Hb denaturation were offset by an increase in Hb-inhibiting carbon surface oxides. Knowledge of these mechanisms shows the impact of alcohols on both Hb and carbon electrodes, allows for thoughtful design of the Hb-sensing system, is vital for proper analysis of Hb electroactivity in the presence of these alcohols (e.g., when used as binder solvents for immobilizing Hb into films), and provides fundamental understanding of the Hb-carbon interactions.

Phosphonic Acids on an Atomically Defined Oxide Surface: The Binding Motif Changes with Surface Coverage

We have studied the anchoring mechanism of a phosphonic acid on an atomically defined oxide surface. Using time-resolved infrared reflection absorption spectroscopy, we investigated the reaction of deuterated phenylphosphonic acid (DPPA, C₆H₅PO₃D₂) with an atomically defined Co₃O₄(111) surface in situ during film growth by physical vapor deposition. We show that the binding motif of the phosphonate anchor group changes as a function of coverage. At low coverage, DPPA binds in the form of a chelating tridentate phosphonate, while a transition to a chelating bidentate occurs close to monolayer saturation coverage. However, the coverage-dependent change in the binding motif is not associated with a major change of the molecular orientation, suggesting that the rigid phosphonate linker always maintains the DPPA in a strongly tilted orientation irrespective of the surface coverage.

Peptide Modified ZnO Nanoparticles as Gas Sensors Array for Volatile Organic Compounds (VOCs)

In this work a peptide based gas sensor array based of ZnO nanoparticles (ZnONPs) has been realized. Four different pentapeptides molecularly modeled for alcohols and esters having cysteine as a common spacer have been immobilized onto ZnONPs. ZnONPs have been morphologically and spectroscopically characterized. Modified nanoparticles have been then deposited onto quartz crystal microbalances (QCMs) and used as gas sensors with nitrogen as carrier gas. Analysis of the pure compounds modeled demonstrated a nice fitting of modeling with real data. The peptide based ZnONPs had very low sensitivity to water, compared to previously studied AuNPs peptide based gas sensors allowing the use of the array on samples with high water content. Real samples of fruit juices have been assayed; stability of the signal, good repeatability, and discrimination ability of the array was achieved.

Insight into induced charges at metal surfaces and biointerfaces using a polarizable Lennard-Jones potential

Metallic nanostructures have become popular for applications in therapeutics, catalysts, imaging, and gene delivery. Molecular dynamics simulations are gaining influence to predict nanostructure assembly and performance; however, instantaneous polarization effects due to induced charges in the free electron gas are not routinely included. Here we present a simple, compatible, and accurate polarizable potential for gold that consists of a Lennard–Jones potential and a harmonically coupled core-shell charge pair for every metal atom. The model reproduces the classical image potential of adsorbed ions as well as surface, bulk, and aqueous interfacial properties in excellent agreement with experiment. Induced charges affect the adsorption of ions onto gold surfaces in the gas phase at a strength similar to chemical bonds while ions and charged peptides in solution are influenced at a strength similar to intermolecular bonds. The proposed model can be applied to complex gold interfaces, electrode processes, and extended to other metals.

Molecular dynamics models for predicting the behavior of metallic nanostructures typically do not take into account polarization effects in metals. Here, the authors introduce a polarizable Lennard–Jones potential that provides quantitative insight into the role of induced charges at metal surfaces and related complex material interfaces.

Screening of peptide probe binding to particulate matter with a high metal content

Particulate matter (PM) is becoming an increasing health concern and there is a need to develop detection methods to keep its harmful effects in check. Generation of reactive oxygen species (ROS) by PM is often associated with metal compounds, hence our aim is to screen for a peptide probe towards improved collection and the detection of PM having a high metal content. Peptides are putative recognition molecules due to their versatility and ease of modification to enhance their binding selectivities. PM binding peptides were screened using the peptide array and different binding behaviors in terms of different spot colors (yellow, mixed and gray), indicating the different composition of bound PMs, were observed. The strongest binding peptides were identified as follows: NHVNTNYYPTLH (gray), NGYYPHSHSYHQ (mixed) and HHLHWPHHHSYT (yellow), with relative binding ratios of 125%, 144% and 136%, in comparison with WQDFGAVRSTRS, a peptide screened from a phage display in our previous study. Inductively coupled plasma mass spectrometry (ICPMS) analyses revealed that Co, Ni and Zn content in the PM bound to the HHLHWPHHHSYT peptide spot were respectively 12.5, 15.8 and 7.8 times that of the PM bound to no peptide spot, suggesting this peptide probe is applicable to collect PM with a high metal content.

Engineering the Surface of Therapeutic "Living" Cells

Biological cells are complex living machines that have garnered significant attention for their potential to serve as a new generation of therapeutic and delivery agents. Because of their secretion, differentiation, and homing activities, therapeutic cells have tremendous potential to treat or even cure various diseases and injuries that have defied conventional therapeutic strategies. Therapeutic cells can be systemically or locally transplanted. In addition, with their ability to express receptors that bind specific tissue markers, cells are being studied as nano- or microsized drug carriers capable of targeted transport. Depending on the therapeutic targets, these cells may be clustered to promote intercellular adhesion. Despite some impressive results with preclinical studies, there remain several obstacles to their broader development, such as a limited ability to control their transport, engraftment, secretion and to track them in vivo. Additionally, creating a particular spatial organization of therapeutic cells remains difficult. Efforts have recently emerged to resolve these challenges by engineering cell surfaces with a myriad of bioactive molecules, nanoparticles, and microparticles that, in turn, improve the therapeutic efficacy of cells. This review article assesses the various technologies developed to engineer the cell surfaces. The review ends with future considerations that should be taken into account to further advance the quality of cell surface engineering.