This study demonstrates a biosensing platform facilitated by localized surface plasmonic resonance (LSPR) on a silicon (Si) nanopillar metasurface mediated by the presence of cephalexin (Cef) antibiotics in solution. The metasurface is designed to exhibit narrow quadrupolar Mie resonances that when coupled with bovine serum albumin-coated (BSA-coated) plasmonic gold nanospheres (BSANS) will produce an appreciable redshift at the peak resonance wavelength, occurring only in the presence of the target antibiotic. To optimize the performance of the Si nanopillars, the finite element method is utilized to fine-tune their diameters, heights, and periodicity, along with improvements to the fabrication techniques, under the BSANS-antibiotic binding assay. The metasurface sensor is directly fabricated via a facile photolithographic process using silicon wafers. Through the detection assay, this device exhibited a significant 22 nm wavelength shift resulting from changes to the local refractive index in the presence of the BSANS-antibiotic coupling. This phenomenon is facilitated through the presence of cephalexin down to 0.3 μg mL for the binding between the plasmonic nanoparticles and the metasurface allowing for sensitive and real-time detection.

Recently, single-walled carbon nanotube-based optical biosensors have been shown to detect hydrolase activity directly on target substrates such as proteins and peptides. This study presents a metastable protein conjugation approach to immobilize more hydrophobic proteins and enhance the sensitivity of protease detection. The method combines covalent conjugation of substrate proteins via carbodiimide chemistry (EDC/NHS) with non-covalent polymer wrapping of SWCNT, in this case, carboxymethyl cellulose. The formation of protein-SWCNT complexes as a result of multi-site conjugation between the proteins and carboxyl groups, enabled iterative pelleting, washing, and resuspension steps to be applied to the probes which allowed for removal of unbound proteins and residual materials, enhancing the sensor's sensitivity by approximately threefold, reaching an LOD of 6.4 ng/ml in a 5 minute reaction. This immobilization approach is applied to the ECM proteins such as gelatin and collagen and used to detect ECM degrading enzymes' activity. ECM degrading enzymes caused a fluorescent intensity decrease of the SWCNT probes, enabling quantification of enzyme concentration between the range 160 ng/ml to 100 µg/ml within 5 minutes of reaction. This hybrid approach provides a rapid and sensitive platform for detecting extracellular degrading enzymes with potential applications in cancer diagnosis and prognosis, wound healing, high-throughput screening for enzyme inhibitors and drug discovery.

We present a proof-of-principle device for axial high-resolution operation that combines a deoxyribonucleic acid (DNA) origami with a functionalized graphene layer, analyzed by nanoscopy. Along the DNA origami structure, we bind ATTO-488 fluorophores at specific distances from graphene, from where we expect specific fluorescence lifetime values due to nearfield energy transfer processes. These are characterized by Fluorescence Lifetime Imaging Microscopy (FLIM). Through modulation of the electrostatic potential of graphene under electrical gating, we observe changes in the fluorescence lifetimes. These are understood as the result of changed energy transfer coupling conditions between the fluorophore and graphene's electronic states, combined with a vertical displacement of the DNA origami structure that matches molecular dimensions. We provide a hybrid architecture whose nanoscale operation depends on the applied voltage regime. A potential application of these findings may be envisioned for biocompatible sensing approaches, in medical or environmental sensing.

Biphasic environments can enable successful chemical reactions where any single solvent results in poor substrate solubility or poor catalyst reactivity. For screening biphasic reactions at high throughput, a platform based on microfluidic double emulsions can use widely available FACS (Fluorescence Activated Cell Sorting) machines to screen millions of picoliter reactors in a few hours. However, encapsulating biphasic reactions within double emulsions to form FACS-sortable droplet picoreactors requires optimized solvent phases and surfactants to produce triple emulsion droplets that are stable over multi-hour assays and compatible with desired reaction conditions. This work demonstrates such FACS-sortable triple emulsion picoreactors with a fluorocarbon shell and biphasic octanol-in-water core. First, surfactants are screened to stabilize octanol-in-water emulsions for the picoreactor core. With these optimized conditions, stable triple emulsion picoreactors (>70% of droplets survived to 24 hr), produced protein in the biphasic core via cell-free protein synthesis are generated, and sorted these triple emulsions based on fluorescence using a commercial FACS sorter at >100 Hz with 75-80% of droplets recovered. Finally, an in-droplet lipase assay with a fluorogenic resorufin substrate that partitions into octanol is demonstrated. These triple emulsion picoreactors have the potential for future screening bead-encoded catalyst libraries, including enzymes such as lipases for biofuel production.

Artificial active colloids have been an active area of research in the field of active matter and microrobotic systems. In particular, light driven semi-conductor particles have been shown to display interesting behaviors ranging from phototaxis (movement toward or away from a light source), rising from the substrate, inter-particle attraction, attraction to the substrate, or other phenomenon. However, these observations involve multiple different designs of particles in varying conditions, making it unclear how the experimental parameters, such as pH, peroxide concentration, and light intensity, affect the outcomes. In this work, a peanut-shaped hematite semi-conductor particle was shown to exhibit a rich range of behavior as a function of the experimental conditions. The particles show rising, sticking, phototaxis, and in-plane alignment of their long axes perpendicular to a magnetic field. A theoretical model accounting for gravity, van der Waals forces, electric double layer interactions with the glass surface, and self-diffusiophoresis is formulated to describe the system. Incorporating experimental data for the dependence of various properties on pH and ionic concentrations, the balance of competing effects in the model explains many of the observed behaviors, providing insight into the relevant physical phenomena and how different environmental conditions can lead to such a rich diversity of behavior.

Poly(ethylene glycol)-norbornene (e.g., PEGNB) is a versatile macromer amenable to step-growth thiol-norbornene photopolymerization and inverse electron demand Diels-Alder (iEDDA) click reaction. The translational potentials of PEGNB-based hydrogels have been realized in the areas of stem cell differentiation, disease modeling, implantable therapeutic devices, and controlled release of therapeutics. Even with these advances, prior methods for synthesizing PEGNB all required heavy use of organic solvents that pose significant environmental and personal health burdens. Here, we report an all-aqueous synthesis of PEG-amide-norbornene-carboxylate (PEGaNB) via reacting carbic anhydride (CA) with multi-arm amino-terminated PEG. Like previously reported ester-bearing counterparts (i.e., PEGNB and PEGeNB), PEGaNB was readily crosslinked into modular hydrogels by either thiol-norbornene photopolymerization or tetrazine-norbornene iEDDA click reaction. Unlike its ester-bearing counterparts, PEGaNB crosslinked thiol-norbornene hydrogels provided long-term hydrolytic stability. However, through blending PEGaNB with hydrolytically labile PEGeNB, hydrogels could be engineered to undergo tunable hydrolytic degradation. The versatility of PEGaNB was further demonstrated via high-fidelity digital light processing (DLP) printing and encapsulation and maintenance of human induced pluripotent stem cells (hiPSCs).

Implanted medical devices often face the challenge of infections, which can compromise their successful integration and use. To address this issue, this study demonstrates the covalent grafting of a tannin-based antimicrobial biopolymer tanfloc (TAN) onto the titania nanotube arrays (TiNTs) surface to enhance antibacterial properties. Due to its polyphenolic and ionic structural configuration, tanfloc possesses unique properties that enable it to interact with and disrupt bacterial cell walls and membranes. Combining the topographical effect of TiNTs with the inherent antibacterial properties of tanfloc, this approach aims to mitigate bacterial threats on medical implants effectively. The successful attachment of tanfloc on TiNTs was confirmed through X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR). The antibacterial and antibiofilm efficacy of the tanfloc-functionalized TiNTs was evaluated against (Gram-positive) and (Gram-negative) bacteria. The findings suggest that the covalent conjugation of tanfloc onto TiNTs is a promising approach to improve the infection resistance of titanium-based medical implants, with potential applications in orthopedic, dental, and other biomedical device areas.

Coculture of intestinal bacteria with primary human intestinal epithelium provides a valuable tool for investigating host-colon bacterial interactions and for testing and screening therapeutics. However, most current intestinal model systems lack key physiological features of the in vivo colon, such as both a proper oxygen microenvironment and a mucus layer. In this work, a new in vitro colonic microphysiological system is demonstrated with a cell-derived, functional mucus that closely resembles the in vivo colonic mucosa and apical microenvironment by employing an anaerobic air-liquid interface culture. The human primary colon epithelial cells in this new in vitro system exhibit high cell viability (>98%) with ≈100 μm thick functional mucus layer on average. Successful coculture of model anaerobic gut bacterial strains and without loss in human cell viability demonstrates that this new model can be an invaluable tool for future studies of the impact of commensal and pathogenic bacteria on the colon.

Sensing of viral antigens has become a critical tool in combating infectious diseases. Current sensing techniques have a tradeoff between sensitivity and time of detection; with 10-30 min of detection time at a relatively low sensitivity and 6-12 h of detection at a high (picomolar) sensitivity. In this research, uniquely nanoengineered interfaces are demonstrated on 3D electrodes that enable the detection of spike antigens of SARS-CoV-2 and their variants in seconds at femtomolar concentrations with excellent specificity, thus, overcoming this tradeoff. The 3D electrodes, manufactured using a high-resolution aerosol jet 3D nanoprinter, consist of a microelectrode array of sintered gold nanoparticles coated with graphene and antibodies specific to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike antigens. An impedance-based sensing modality is employed to sense several pseudoviruses of SARS-CoV-2 variants of concern (VOCs). This device is sensitive to most of the pseudoviruses of SARS-CoV-2 VOCs. A high sensitivity of 100 fm, along with a low limit-of-detection of 9.2 fm within a test range of 0.1-1000 pm, and a detection time of 43 s are shown. This work illustrates that effective nano-bioengineering of interfaces can be used to create an ultrafast and ultrasensitive healthcare diagnostic tool for combating emerging infections.

Slippery surfaces (i.e., surfaces that display high liquid droplet mobility) are receiving significant attention due to their biofluidic applications. Non-textured, all-solid, slippery hydrophilic (SLIC) surfaces are an emerging class of rare and counter-intuitive surfaces. In this work, the interactions of blood and bacteria with SLIC surfaces are investigated. The SLIC surfaces demonstrate significantly lower platelet and leukocyte adhesion (≈97.2% decrease in surface coverage), and correspondingly low platelet activation, as well as significantly lower bacterial adhesion (≈99.7% decrease in surface coverage of live and ≈99.6% decrease in surface coverage of live ) and proliferation compared to untreated silicon substrates, indicating their potential for practical biomedical applications. The study envisions that the SLIC surfaces will pave the path to improved biomedical devices with favorable blood and bacteria interactions.

Droplet microfluidics enables compartmentalized reactions in small scales and has been utilized for a variety of applications across chemical analysis, material science, and biology. While droplet microfluidics is a successful technology, barriers include high "activation energy" to develop custom applications and complex peripheral equipment. These barriers limit the adoption of droplet microfluidics in labs or prototyping environments. We demonstrate for the first time an open channel droplet microfluidic system that autonomously generates droplets at low Capillary numbers. Hundreds of droplets are produced in a run using only an open channel, pipettes, and a commercially available carrier fluid. Conceptual applications that showcase the process of droplet generation, splitting, transport, incubation, mixing, and sorting are demonstrated. The open nature of the device enables the use of physical tools such as tweezers and styli to directly access the system; with this, a new method of droplet sorting and transfer unique to open systems is demonstrated. This platform offers enhanced usability, direct access to the droplet contents, easy manufacturability, compact footprint, and high customizability. This design is a first step in exploring the space of power-free open droplet microfluidic systems and provides design rules for similar channel designs.

A novel localized surface plasmon resonance (LSPR) system based on the coupling of gold nanomushrooms (AuNMs) and gold nanoparticles (AuNPs) is developed to enable a significant plasmonic resonant shift. The AuNP size, surface chemistry, and concentration are characterized to maximize the LSPR effect. A 31 nm redshift is achieved when the AuNMs are saturated by the AuNPs. This giant redshift also increases the full width of the spectrum and is explained by the 3D finite-difference time-domain (FDTD) calculation. In addition, this LSPR substrate is packaged in a microfluidic cell and integrated with a CRISPR-Cas13a RNA detection assay for the detection of the SARS-CoV-2 RNA targets. Once activated by the target, the AuNPs are cleaved from linker probes and randomly deposited on the AuNM substrate, demonstrating a large redshift. The novel LSPR chip using AuNP as an indicator is simple, specific, isothermal, and label-free; and thus, provides a new opportunity to achieve the next generation multiplexing and sensitive molecular diagnostic system.

Polydiacetylene (PDA) Langmuir films are well known for their blue to red chromatic transitions in response to a variety of stimuli, including UV light, heat, bio-molecule bindings and mechanical stress. In this work, we detail the ability to tune PDA Langmuir films to exhibit discrete chromatic transitions in response to applied mechanical stress. Normal and shear-induced transitions were quantified using the Surface Forces Apparatus and established to be binary and tunable as a function of film formation conditions. Both monomer alkyl tail length and metal cations were used to manipulate the chromatic transition force threshold to enable discrete force sensing from ~50 to ~500 nN μm for normal loading and ~2 to ~40 nN μm for shear-induced transitions, which are appropriate for biological cells. The utility of PDA thin-film sensors was demonstrated with the slime mold . The fluorescence readout of the films enabled: the area explored by to be visualized, the forces involved in locomotion to be quantified, and revealed novel puncta formation potentially associated with sampling its environment.

Near-infrared (NIR) photothermal therapy by microneedles (MNs) exhibits high potential against skin diseases. However, high costs, photobleaching of organic agents, low long-term stability, and potential nanotoxicity limit the clinical translation of photothermal MNs. Here, photothermal MNs are developed by utilizing Au nanoaggregates made by flame aerosol technology and incorporated in water-insoluble polymer matrix to reduce intradermal nanoparticle (NP) deposition. The individual Au interparticle distance and plasmonic coupling within the nanoaggregates are controlled by the addition of a spacer during their synthesis rendering the Au nanoaggregates highly efficient NIR photothermal agents. In situ aerosol deposition of Au nanoaggregates on MN molds results in the fabrication of photothermal MNs with thin plasmonic layers. The photothermal performance of these MN arrays is compared to ones made by three methods utilizing NP dispersions, and it is found that similar temperatures are reached with 28-fold lower Au mass due to reduced light scattering losses of the thin layers. Finally, all developed photothermal MN arrays here cause clinically relevant hyperthermia at benign laser intensities while reducing intradermal NP deposition 127-fold compared to conventional MNs made with water-soluble polymers. Such rational design of photothermal MNs requiring low laser intensities and minimal NP intradermal accumulation sets the basis for their safe clinical translation.

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is continuously infecting people all around the world since its outbreak in 2019. Studies for numerous infection detection strategies are continuing. The sensitivity of detection methods is crucial to separate people with mild infections from people who are asymptomatic. In this sense, a strategy that would help to capture and isolate the SARS-CoV-2 virus prior to tests can be effective and beneficial. To this extent, genetically engineered biomaterials grounding from the biofilm protein of are beneficial due to their robustness and adaptability to various application areas. Through functionalizing the biofilm protein, diverse properties can be attained such as enzyme display, nanoparticle production, and medical implant structures. Here, species are employed to express major curli protein CsgA and Griffithsin (GRFT) as fusion proteins, through a complex formation using SpyTag and SpyCatcher domains. In this study, a complex system with a CsgA scaffold harboring the affinity of GRFT against Spike protein to capture and isolate SARS-CoV-2 virus is successfully developed. It is shown that the hybrid recombinant protein can dramatically increase the sensitivity of currently available lateral flow assays for Sars-CoV-2 diagnostics.

Recent advancements in separation and membrane technologies have shown a great potential in removing oil from wastewaters effectively. In addition, the capabilities have improved to fabricate membranes with tunable properties in terms of their wettability, permeability, antifouling, and mechanical properties that govern the treatment of oily wastewaters. Herein, authors have critically reviewed the literature on membrane technology for oil/water separation with a specific focus on: 1) membrane properties and characterization, 2) development of various materials (e.g., organic, inorganic, and hybrid membranes, and innovative materials), 3) membranes design (e.g., mixed matrix nanocomposite and multilayers), and 4) membrane fabrication techniques and surface modification techniques. The current challenges and future research directions in materials and fabrication techniques for membrane technology applications in oil/water separation are also highlighted. Thus, this review provides helpful guidance toward finding more effective, practical, and scalable solutions to tackle environmental pollution by oils.

For individuals who have experienced tooth loss, dental implants are an important treatment option for oral reconstruction. For these patients, alveolar bone augmentation and acceleration of osseointegration optimize implant stability. Traditional oral surgery often requires invasive procedures, which can result in prolonged treatment time and associated morbidity. It has been previously shown that chemical vapor deposition (CVD) polymerization of functionalized [2.2]paracyclophanes can be used to anchor gene encoding vectors onto biomaterial surfaces and local delivery of a bone morphogenetic protein (BMP)-encoding vector can increase alveolar bone volume and density in vivo. This study is the first to combine the use of CVD technology and BMP gene delivery on titanium for the promotion of bone regeneration and bone to implant contact in vivo. BMP-7 tethered to titanium surface enhances osteoblast cell differentiation and alkaline phosphatase activity in vitro and increases alveolar bone regeneration and % bone to implant contact similar to using high doses of exogenously applied BMP-7 in vivo. The use of this innovative gene delivery strategy on implant surfaces offers an alternative treatment option for targeted alveolar bone reconstruction.

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 MoS 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 MoS are sputtered over pre-patterned metal electrical contacts on a glass chip at room temperature. The amorphous MoS is then laser annealed to create an array of semiconducting 2H-MoS transducer regions between metal contacts. The semiconducting crystalline MoS 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 MoS. Electrical resistance measurements of sensors exposed to antigen concentrations ranging from 2-20 000 pg mL 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 to µg mL.

A serological immunoassay based on enzyme-linked immunosorbent assay (ELISA) is a crucial tool for screening and identification of human SARS-CoV-2 seroconversion. Various immunoassays are developed to detect the spike 1 (S1) and nucleocapsid (NP) proteins of SARS-CoV-2; however, these serological tests have low sensitivity. Here, a novel microplate (MP) is developed on which a ZnO nanowire (NW) is fabricated by a modified hydrothermal synthesis method. This plate is coated with SARS-CoV-2 NP and used as a fluorescent immunoassay (FIA) to detect antibodies specific for SARS-CoV-2 NP. Compared with the bare MP, the ZnO-NW MP binds high levels (up to 5 µg mL) of SARS-CoV-2 NP tagged to histidine without any surface treatment. A novel serological assay based on the ZnO-NW MP is more sensitive than a commercial immunoassay, enabling early detection (within <5 days of a reverse transcription polymerase chain reaction-confirmed COVID-19 infection) of anti-SARS-CoV-2 NP IgG antibodies in asymptomatic patients with COVID-19. This is the first assay to detect early antibody responses to SARS-CoV-2 in asymptomatic patients. Therefore, this serological assay will facilitate accurate diagnosis of COVID-19, as well as estimation of COVID-19 prevalence and incidence.

How nanoparticle (NP) mechanical properties impact multivalent ligand-receptor-mediated binding to cell surfaces, the avidity, propensity for internalization, and effects due to crowding remains unknown or unquantified. Through computational analyses, the effects of NP composition from soft, deformable NPs to rigid spheres, effect of tethers, the crowding of NPs at the membrane surface, and the cell membrane properties such as cytoskeletal interactions are addressed. Analyses of binding mechanisms of three distinct NPs that differ in type and rigidity (core-corona flexible NP, rigid NP, and rigid-tethered NP) but are otherwise similar in size and ligand surface density are reported; moreover, for the case of flexible NP, NP stiffness is tuned by varying the internal crosslinking density. Biophysical modeling of NP binding to membranes together with thermodynamic analysis powered by free energy calculations is employed, and it is shown that efficient cellular targeting and uptake of NP functionalized with targeting ligand molecules can be shaped by factors including NP flexibility and crowding, receptor-ligand binding avidity, state of the membrane cytoskeleton, and curvature inducing proteins. Rational design principles that confer tension, membrane excess area, and cytoskeletal sensing properties to the NP which can be exploited for cell-specific targeting of NP are uncovered.