Lateral Flow Assay Biotesting by Utilizing Plasmonic Nanoparticles Made of Inexpensive Metals─Replacing Colloidal Gold

Nanoparticles (NPs) can be conjugated with diverse biomolecules and employed in biosensing to detect target analytes in biological samples. This proven concept was primarily used during the COVID-19 pandemic with gold-NP-based lateral flow assays (LFAs). Considering the gold price and its worldwide depletion, here we show that novel plasmonic NPs based on inexpensive metals, titanium nitride (TiN) and copper covered with a gold shell (Cu@Au), perform comparable to or even better than gold nanoparticles. After conjugation, these novel nanoparticles provided high figures of merit for LFA testing, such as high signals and specificity and robust naked-eye signal recognition. Since the main cost of Au NPs in commercial testing kits is the colloidal synthesis, our development with the Cu@Au and the laser-ablation-fabricated TiN NPs is exciting, offering potentially inexpensive plasmonic nanomaterials for various bioapplications. Moreover, our machine learning study showed that biodetection with TiN is more accurate than that with Au.

Graphene exfoliation using multidomain peptides

Liquid-phase exfoliation using biomolecules in aqueous solution is a promising approach to obtain high quality 2D nanosheets. For example, the well-studied graphene-binding peptide, P1 (sequence HSSYWYAFNNKT), has been previously investigated and shown to have a good ability to exfoliate graphene sheets in aqueous conditions under sonication, maintaining colloidal stability. Building on this, the biomolecular exfoliant and assembly motif (BEAM) peptide, that features a graphene-binding domain at one end and a hexagonal boron nitride (h-BN) binding domain at the other, separated by a 10-carbon fatty acid chain in the centre, is shown to exfoliate graphene sheets from bulk graphite in aqueous media. An in-depth examination of the ability of the BEAM to both facilitate sheet exfoliation under sonication conditions and also maintain colliodal stability is provided through molecular dynamics simulations. These findings open new possibilities for designing multi-functional molecules that can both exfoliate and organise 2D materials into heterostructures under ambient conditions in aqueous media.

Lateral Flow Assays Biotesting by Utilizing Plasmonic Nanoparticles Made of Inexpensive Metals - Replacing Colloidal Gold

Nanoparticles (NPs) can be conjugated with diverse biomolecules and employed in biosensing to detect target analytes in biological samples. This proven concept was primarily used during the COVID-19 pandemic with gold NPs-based lateral flow assays (LFAs). Considering the gold price and its worldwide depletion, here we show that novel plasmonic nanoparticles (NPs) based on inexpensive metals, titanium nitride (TiN) and copper covered with a gold shell (Cu@Au), perform comparable or even better than gold nanoparticles. After conjugation, these novel nanoparticles provided high figures of merit for LFA testing, such as high signals and specificity and robust naked-eye signal recognition. To the best of our knowledge, our study represents the 1st application of laser-ablation-fabricated nanoparticles (TiN) in the LFA and dot-blot biotesting. Since the main cost of the Au NPs in commercial testing kits is in the colloidal synthesis, our development with TiN is very exciting, offering potentially very inexpensive plasmonic nanomaterials for various bio-testing applications. Moreover, our machine learning study showed that the bio-detection with TiN is more accurate than that with Au.

Peptide/Nanoparticle Biointerfaces for Multistep Tandem Catalysis

The realization of multifunctional nanoparticle systems is essential to achieve highly efficient catalytic materials for specific applications; however, their production remains quite challenging. They are typically achieved through the incorporation of multiple inorganic components; however, incorporation of functionality could also be achieved at the organic ligand layer. In this work, we demonstrate the generation of multifunctional nanoparticle catalysts using peptide-based ligands for tandem catalytic functionality. To this end, chimeric peptides were designed that incorporated a Au binding sequence and a catalytic sequence that can drive ester hydrolysis. Using this chimera, Au nanoparticles were prepared, which sufficiently presented the catalytic domain of the peptide to drive tandem catalytic processes occurring at the peptide ligand layer and the Au nanoparticle surface. This work represents unique pathways to achieve multifunctionality from nanoparticle systems tuned by both the inorganic and bio/organic components, which could be highly important for applications beyond catalysis, including theranostics, sensing, and energy technologies.

Laser-Fabricated 2D Molybdenum Disulfide Electronic Sensor Arrays for Rapid, Low-Cost, Ultrasensitive Detection of Influenza A and SARS-Cov-2

Multiplex electronic antigen sensors for detection of SARS-Cov-2 spike glycoproteins and hemagglutinin from influenza A are fabricated using scalable processes for straightforward transition to economical mass-production. The sensors utilize the sensitivity and surface chemistry of a 2D MoS₂ transducer for attachment of antibody fragments in a conformation favorable for antigen binding with no need for additional linker molecules. To make the devices, ultra-thin layers (3 nm) of amorphous MoS₂ are sputtered over pre-patterned metal electrical contacts on a glass chip at room temperature. The amorphous MoS₂ is then laser annealed to create an array of semiconducting 2H-MoS₂ transducer regions between metal contacts. The semiconducting crystalline MoS₂ region is functionalized with monoclonal antibody fragments complementary to either SARS-CoV-2 S1 spike protein or influenza A hemagglutinin. Quartz crystal microbalance experiments indicate strong binding and maintenance of antigen avidity for antibody fragments bound to MoS₂. Electrical resistance measurements of sensors exposed to antigen concentrations ranging from 2-20 000 pg mL^-1 reveal selective responses. Sensor architecture is adjusted to produce an array of sensors on a single chip suited for detection of analyte concentrations spanning six orders of magnitude from pg mL^-1 to µg mL^-1.

Biomarkers and Detection Platforms for Human Health and Performance Monitoring: A Review

Human health and performance monitoring (HHPM) is imperative to provide information necessary for protecting, sustaining, evaluating, and improving personnel in various occupational sectors, such as industry, academy, sports, recreation, and military. While various commercially wearable sensors are on the market with their capability of "quantitative assessments" on human health, physical, and psychological states, their sensing is mostly based on physical traits, and thus lacks precision in HHPM. Minimally or noninvasive biomarkers detectable from the human body, such as body fluid (e.g., sweat, tear, urine, and interstitial fluid), exhaled breath, and skin surface, can provide abundant additional information to the HHPM. Detecting these biomarkers with novel or existing sensor technologies is emerging as critical human monitoring research. This review provides a broad perspective on the state of the art biosensor technologies for HHPM, including the list of biomarkers and their physiochemical/physical characteristics, fundamental sensing principles, and high-performance sensing transducers. Further, this paper expands to the additional scope on the key technical challenges in applying the current HHPM system to the real field.

Examining cellular responses to reconstituted antibody protein liquids

Protein ionic liquids (PIL) are a new class of biologic stabilizers designed to protect the functionality and extend the shelf-life of biotechnological and therapeutic agents making them more readily available, and resistant to austere environments. Protein biorecognition elements such as monoclonal antibodies are commonly utilized therapeutics that require the robust stabilization offered by PILs, but biocompatibility remains an important issue. This study has focused on characterizing the biocompatibility of an antibody based PIL by exposing multiple cells types to a cationized immunoglobulin suspended in an anionic liquid (IgG-IL). The IgG-IL caused no significant alterations in cellular health for all three cell types with treatments < 12.5 µg/mL. Concentrations ≥ 12.5 µg/mL resulted in significant necrotic cell death in A549 and HaCaT cells, and caspase associated cell death in HepG2 cells. In addition, all cells displayed evidence of oxidative stress and IL-8 induction in response to IgG-IL exposures. Therapeutic Ig can be utilized with a wide dose range that extends into concentrations we have found to exhibit cytotoxicity raising a toxicity concern and a need for more extensive understanding of the biocompatibility of IgG-ILs.

Identification of Parameters Controlling Peptide-Driven Graphene Exfoliation in Aqueous Media

Bio-inspired approaches represent potentially transformational methods to fabricate and activate non-natural materials for applications ranging from biomedical diagnostics to energy harvesting platforms. Recently, bio-based methods for the exfoliation of graphene in water have been developed, resulting in peptide-capped nanosheets; however, a clear understanding of the reaction system and peptide ligand structure remains unclear, limiting the advance of such approaches. Here the effects of reaction solution conditions and peptide ligand structure were systematically examined for graphene exfoliation, identifying key parameters to optimize material production. For this, the P1 peptide, identified with affinity for graphene, was exploited to drive exfoliation of bulk graphite to generate the final materials. The peptide was modified at both the N- and C-terminus with a 10-carbon chain fatty acid to explore the effects of a hydrophobic domain on the exfoliation process. The system was examined as a function of sonication time, pH, reagent concentration, and graphite source, where the final materials were fully characterized using a suite of approaches. Collectively, these results demonstrated that maximum graphene production was achieved using the parent P1 peptide after 12 h of sonication under basic conditions. While the exfoliation efficiency was slightly lower for the fatty acid modified peptides, the graphene produced using these biomolecules had fewer defects incorporated, potentially from the wrapping of the nanosheet edge by the aliphatic domain. Such results are important to provide key reaction designs to optimize the reproducibility of graphene exfoliation using biomimetic approaches.

Remote controlled optical manipulation of bimetallic nanoparticle catalysts using peptides

Remote optical manipulation of peptide ligands on bimetallic nanoparticle surfaces allows for tunable catalytic reactivity.

PRADA: Portable Reusable Accurate Diagnostics with nanostar Antennas for multiplexed biomarker screening

Precise monitoring of specific biomarkers in biological fluids with accurate biodiagnostic sensors is critical for early diagnosis of diseases and subsequent treatment planning. In this work, we demonstrated an innovative biodiagnostic sensor, portable reusable accurate diagnostics with nanostar antennas (PRADA), for multiplexed biomarker detection in small volumes (~50 μl) enabled in a microfluidic platform. Here, PRADA simultaneously detected two biomarkers of myocardial infarction, cardiac troponin I (cTnI), which is well accepted for cardiac disorders, and neuropeptide Y (NPY), which controls cardiac sympathetic drive. In PRADA immunoassay, magnetic beads captured the biomarkers in human serum samples, and gold nanostars (GNSs) "antennas" labeled with peptide biorecognition elements and Raman tags detected the biomarkers via surface-enhanced Raman spectroscopy (SERS). The peptide-conjugated GNS-SERS barcodes were leveraged to achieve high sensitivity, with a limit of detection (LOD) of 0.0055 ng/ml of cTnI, and a LOD of 0.12 ng/ml of NPY comparable with commercially available test kits. The innovation of PRADA was also in the regeneration and reuse of the same sensor chip for ~14 cycles. We validated PRADA by testing cTnI in 11 de-identified cardiac patient samples of various demographics within a 95% confidence interval and high precision profile. We envision low-cost PRADA will have tremendous translational impact and be amenable to resource-limited settings for accurate treatment planning in patients.

Material composition and peptide sequence affects biomolecule affinity to and selectivity for h-boron nitride and graphene

Nanosheet heterostructures offer emergent optical/electronic properties. These could be achieved using selective materials binding peptides, but lack of understanding of selectivity impedes advancement. Here we examine peptides with affinity for graphene or h-BN using quantitative experiments and molecular simulation to identify traits for design of 2D nanosheet selective peptides.

Disulfide Crosslinked Hydrogels Made From the Hydra Stinging Cell Protein, Minicollagen-1

Minicollagens from cnidarian nematocysts are attractive potential building blocks for the creation of strong, lightweight and tough polymeric materials with the potential for dynamic and reconfigurable crosslinking to modulate functionality. In this study, the Hydra magnipapillata minicollagen-1 isoform was recombinantly expressed in bacteria, and a high throughput purification protocol was developed to generate milligram levels of pure protein without column chromatography. The resulting minicollagen-1 preparation demonstrated spectral properties similar to those observed with collagen and polyproline sequences as well as the ability to self-assemble into oriented fibers and bundles. Photo-crosslinking with Ru(II)( bpy ) 3 2 + was used to create robust hydrogels that were analyzed by mechanical testing. Interestingly, the minicollagen-1 hydrogels could be dissolved with reducing agents, indicating that ruthenium-mediated photo-crosslinking was able to induce disulfide metathesis to create the hydrogels. Together, this work is an important first step in creating minicollagen-based materials whose properties can be manipulated through static and reconfigurable post-translational modifications.

Chiral Restructuring of Peptide Enantiomers on Gold Nanomaterials

The use of biomolecules has been invaluable at generating and controlling optical chirality in nanomaterials; however, the structure and properties of the chiral biotemplate are not well understood due to the complexity of peptide-nanoparticle interactions. In this study, we show that the complex interactions between d-peptides and gold nanomaterials led to a chiral restructuring of peptides as demonstrated by circular dichroism and proteolytic cleavage of d-peptides via gold-mediated inversion of peptide chirality. The gold nanoparticles synthesized using d-peptide produce a highly ordered atomic surface and restructured peptide bonds for enzyme cleavage. Differences in gold nanoparticle catalyzed reduction of 4-nitrophenol were observed on the basis of the chiral peptide used in nanoparticle synthesis. Notably, the proteolytic cleavage of d-peptides on gold provides an opportunity for designing nanoparticle based therapeutics to treat peptide venoms, access new chemistries, or modulate the catalytic activity of nanomaterials.

Biomimetic strategies to produce catalytically reactive CuS nanodisks

Copper sulfide materials have diverse applications from cancer therapy to environmental remediation due to their narrow bandgap and easily tuned plasmon. The synthesis of these materials often involves toxic reagents and harsh conditions where biomimetic methods may provide opportunities to produce these structures under sustainable conditions. To explore this capability, simple amino acids were exploited as biological ligands for the ambient synthesis of CuS materials. Using an aqueous-based approach, CuS nanodisks were prepared using acid-containing amino acid molecules that stabilize the materials against bulk aggregation. These structures were fully characterized by UV-vis analysis, transmission electron microscopy, dynamic light scattering, atomic force microscopy, selected area electron diffraction, and X-ray diffraction, which confirmed the formation of CuS. The materials possessed a vibrant plasmon band in the near IR region and demonstrated enhanced photocatalytic reactivity for the advanced oxidation of organic dyes in water. These results demonstrate a room temperature synthetic route to optically important materials, which could have important application in catalysis, optics, nanomedicine, etc.

Competition-Enhanced Ligand Selection to Identify DNA Aptamers

Competition-enhanced ligand screening (CompELS) was employed to rapidly screen through large DNA libraries to identify single-stranded, oligonucleotide-based ligands called aptamers that bind to a nonbiological target. This previously unreported aptamer screening approach involves the repeated introduction of unenriched random sequence populations during the biopanning process, but avoids iterative elution and polymerase chain reaction (PCR) amplification steps inherent to traditional SELEX (systematic evolution of ligands by exponential enrichment) screening. In this study, 25 aptamers were identified against a gold surface via CompELS and evaluated to identify patterns in primary structures and predicted secondary structures. Following a final one-round competition experiment with the 25 identified aptamers, one particular aptamer sequence (1N) emerged as the most competitive adsorbate species for the gold substrate. Binding analysis indicated at least an order of magnitude difference in the binding affinity of 1N ( K_d = 5.6 × 10^-10 M) compared to five other high affinity aptamer candidates ( K_d = 10^-8-10^-9 M) from identical secondary structure families. Collectively, these studies introduce a rapid, reliable screening and ranking platform along with a classification scheme well-suited for identifying and characterizing aptamers for nonbiological as well as biological targets.

Advancing Peptide-Based Biorecognition Elements for Biosensors Using in-Silico Evolution

Sensors for human health and performance monitoring require biological recognition elements (BREs) at device interfaces for the detection of key molecular biomarkers that are measurable biological state indicators. BREs, including peptides, antibodies, and nucleic acids, bind to biomarkers in the vicinity of the sensor surface to create a signal proportional to the biomarker concentration. The discovery of BREs with the required sensitivity and selectivity to bind biomarkers at low concentrations remains a fundamental challenge. In this study, we describe an in-silico approach to evolve higher sensitivity peptide-based BREs for the detection of cardiac event marker protein troponin I (cTnI) from a previously identified BRE as the parental affinity peptide. The P2 affinity peptide, evolved using our in-silico method, was found to have ∼16-fold higher affinity compared to the parent BRE and ∼10 fM (0.23 pg/mL) limit of detection. The approach described here can be applied towards designing BREs for other biomarkers for human health monitoring.

Bio-Optics and Bio-Inspired Optical Materials

Through the use of the limited materials palette, optimally designed micro- and nanostructures, and tightly regulated processes, nature demonstrates exquisite control of light-matter interactions at various length scales. In fact, control of light-matter interactions is an important element in the evolutionary arms race and has led to highly engineered optical materials and systems. In this review, we present a detailed summary of various optical effects found in nature with a particular emphasis on the materials and optical design aspects responsible for their optical functionality. Using several representative examples, we discuss various optical phenomena, including absorption and transparency, diffraction, interference, reflection and antireflection, scattering, light harvesting, wave guiding and lensing, camouflage, and bioluminescence, that are responsible for the unique optical properties of materials and structures found in nature and biology. Great strides in understanding the design principles adapted by nature have led to a tremendous progress in realizing biomimetic and bioinspired optical materials and photonic devices. We discuss the various micro- and nanofabrication techniques that have been employed for realizing advanced biomimetic optical structures.

Creation of energetic biothermite inks using ferritin liquid protein

Energetic liquids function mainly as fuels due to low energy densities and slow combustion kinetics. Consequently, these properties can be significantly increased through the addition of metal nanomaterials such as aluminium. Unfortunately, nanoparticle additives are restricted to low mass fractions in liquids because of increased viscosities and severe particle agglomeration. Nanoscale protein ionic liquids represent multifunctional solvent systems that are well suited to overcoming low mass fractions of nanoparticles, producing stable nanoparticle dispersions and simultaneously offering a source of oxidizing agents for combustion of reactive nanomaterials. Here, we use iron oxide-loaded ferritin proteins to create a stable and highly energetic liquid composed of aluminium nanoparticles and ferritin proteins for printing and forming 3D shapes and structures. In total, this bioenergetic liquid exhibits increased energy output and performance, enhanced dispersion and oxidation stability, lower activation temperatures, and greater processability and functionality.

Optical Modulation of Azobenzene-Modified Peptide for Gold Surface Binding

The ability to precisely and remotely modulate reversible binding interactions between biomolecules and abiotic surfaces is appealing for many applications. To achieve this level of control, an azobenzene-based optical switch is added to nanoparticle-binding peptides in order to switch peptide conformation and attenuate binding affinity to gold surfaces via binding and dissociation of peptides.

Peptide Functionalized Gold Nanorods for the Sensitive Detection of a Cardiac Biomarker Using Plasmonic Paper Devices

The sensitivity of localized surface plasmon resonance (LSPR) of metal nanostructures to adsorbates lends itself to a powerful class of label-free biosensors. Optical properties of plasmonic nanostructures are dependent on the geometrical features and the local dielectric environment. The exponential decay of the sensitivity from the surface of the plasmonic nanotransducer calls for the careful consideration in its design with particular attention to the size of the recognition and analyte layers. In this study, we demonstrate that short peptides as biorecognition elements (BRE) compared to larger antibodies as target capture agents offer several advantages. Using a bioplasmonic paper device (BPD), we demonstrate the selective and sensitive detection of the cardiac biomarker troponin I (cTnI). The smaller sized peptide provides higher sensitivity and a lower detection limit using a BPD. Furthermore, the excellent shelf-life and thermal stability of peptide-based LSPR sensors, which precludes the need for special storage conditions, makes it ideal for use in resource-limited settings.

Bioinspired High-Performance Energetic Materials Using Heme-Containing Crystals

Synthetic hemozoin crystals (β-hematin) are assembled with aluminium nanoparticles (nAl) to create a nanomaterial composite that is highly energetic and reactive. The results here demonstrate that hemozoin rapidly oxidizes the nAl fuel to release large amounts of energy (+12.5 ± 2.4 kJ g(-1) ).

Elucidation of peptide-directed palladium surface structure for biologically tunable nanocatalysts

Peptide-enabled synthesis of inorganic nanostructures represents an avenue to access catalytic materials with tunable and optimized properties. This is achieved via peptide complexity and programmability that is missing in traditional ligands for catalytic nanomaterials. Unfortunately, there is limited information available to correlate peptide sequence to particle structure and catalytic activity to date. As such, the application of peptide-enabled nanocatalysts remains limited to trial and error approaches. In this paper, a hybrid experimental and computational approach is introduced to systematically elucidate biomolecule-dependent structure/function relationships for peptide-capped Pd nanocatalysts. Synchrotron X-ray techniques were used to uncover substantial particle surface structural disorder, which was dependent upon the amino acid sequence of the peptide capping ligand. Nanocatalyst configurations were then determined directly from experimental data using reverse Monte Carlo methods and further refined using molecular dynamics simulation, obtaining thermodynamically stable peptide-Pd nanoparticle configurations. Sequence-dependent catalytic property differences for C-C coupling and olefin hydrogenation were then elucidated by identification of the catalytic active sites at the atomic level and quantitative prediction of relative reaction rates. This hybrid methodology provides a clear route to determine peptide-dependent structure/function relationships, enabling the generation of guidelines for catalyst design through rational tailoring of peptide sequences.

Titania binding peptides as templates in the biomimetic synthesis of stable titania nanosols: insight into the role of buffers in peptide-mediated mineralization

In this Article, we report the unusual behavior of two peptides (Ti-1 (QPYLFATDSLIK) and Ti-2 (GHTHYHAVRTQT)) with high affinity for titania that efficiently promote titania mineralization from an aqueous titanium bisammonium lactatodihydroxide (TiBALDH) solution, yielding small (ca. 4 nm) titania nanoparticles. As a result, we were able to produce for the first time using a biomimetic approach highly stable sub-10-nm titania sols. Both sequences show a high titania mineralization activity per unit peptide concentration and a capacity to control particle size and stabilize nanoparticles through specific surface interactions. We also show that phosphate ions disrupt the controlled particle formation and stabilization achieved in the presence of the two peptides. The products obtained from phosphate buffered solutions are titanium-containing materials (not pure oxide) with poor morphological control similar to those previously reported by others. Our results provide important insights into understanding the mechanism of titania mineralization in a range of different aqueous media (water, Tris, and phosphate buffer).