Interfacing neural cells with typical microelectronics materials for future manufacturing.

The biocompatibility of materials used in electronic devices is critical for the development of implantable devices like pacemakers and neuroprosthetics, as well as in future biomanufacturing. Biocompatibility refers to the ability of these materials to interact with living cells and tissues without causing an adverse response. Therefore, it is essential to evaluate the biocompatibility of metals and semiconductor materials used in electronic devices to ensure their safe use in medical applications. Here, we evaluated the biocompatibility of a collection of diced silicon chips coated with a variety of metal thin films, interfacing them with different cell types, including murine mastocytoma cells in suspension culture, adherent NIH 3T3 fibroblasts, and human induced pluripotent stem cell (iPSC)-derived neural progenitor cells (NPCs). All materials tested were biocompatible and showed the potential to support neural differentiation of iPSC-NPCs, creating an opportunity to use these materials in a scalable production of a range of biohybrid devices such as electronic devices to study neural behaviors and neuropathies.

Dual detection of COVID-19 antigens and antibodies using nanoscale fluorescent plasmonic substrates.

There is a continuing need for biosensors that can be used in the diagnosis of COVID-19 infection and to measure a subject's immune response to the virus itself (SARS-CoV-2). In this study, grating-coupled fluorescent plasmonic (GC-FP)-based detection of SARS-CoV-2 antigens was coupled with antibody detection to yield a dual-mode detection assay. Pairs of capture and detection antibodies were screened for direct detection of the SARS-CoV-2 nucleocapsid (Nuc) antigen, which were then combined with an existing GC-FP antibody detection assay. Nuc could be detected as low as 1 µg/mL concentrations, while antibodies were detectable to 50 ng/mL. The dual detection assay was tested by adding purified Nuc antigen to serum from a polymerase chain reaction (PCR)-positive COVID-19-infected individual. Using this sample, co-detection of Nuc antigen and anti-spike protein antibodies was successfully performed on a single GC-FP chip. Total assay time was 1 h, making this the first known example of rapid dual antibody and antigen detection on the same biosensor chip.

Monitoring and modulation of the tumor microenvironment for enhanced cancer modeling.

Cancer treatments utilizing biologic or cytotoxic drugs compose the frontline of therapy, and though gains in treatment efficacy have been persistent in recent decades, much work remains in understanding cancer progression and treatment. Compounding this situation is the low rate of success when translating preclinical drug candidates to the clinic, which raises costs and development timelines. This underperformance is due in part to the poor recapitulation of the tumor microenvironment, a critical component of cancer biology, in cancer model systems. New technologies capable of both accurately observing and manipulating the tumor microenvironment are needed to effectively model cancer response to treatment. In this review, conventional cancer models are summarized, and a primer on emerging techniques for monitoring and modulating the tumor microenvironment is presented and discussed.

Smart fracture plate for quantifying fracture healing: Preliminary efficacy in a biomechanical model.

The diagnosis of fracture nonunion following plate osteosynthesis is subjective and frequently ambiguous. Initially following osteosynthesis, loads applied to the bone are primarily transmitted through the plate. However, as callus stiffness increases, the callus is able to bear load proportional to its stiffness while forces through the plate decrease. The purpose of this study was to use a "smart" fracture plate to distinguish between phases of fracture healing by measuring forces transmitted through the plate. A wireless force sensor and small adapter were placed on the outside of a distal femoral locking plate. The adapter converts the slight bending of the plate under axial load into a transverse force which is measurable by the sensor. An osteotomy was created and then plated in the distal femur of biomechanical Sawbones. Specimens were loaded to simulate single-leg stance first with the osteotomy defect empty (acute healing), then sequentially filled with silicone (early callus) and then polymethyl methacrylate (hard callus). There was a strong correlation between applied axial load and force measured by the "smart" plate. Data demonstrate statistically significant differences between each phase of healing with as little as 150 N of axial load applied to the femur. Forces measured in the plate were significantly different between acute (100%), early callus (66.4%), and hard callus (29.5%). This study demonstrates the potential of a "smart" fracture plate to distinguish between phases of healing. These objective data may enable early diagnosis of nonunion and enhance outcomes for patients.

Rapid and Quantitative Detection of Human Antibodies against the 2019 Novel Coronavirus SARS CoV2 and Its Variants as a Result of Vaccination and Infection.

Measuring the antibody response to 2019 SARS CoV2 is critical for diagnostic purposes, for monitoring the prevalence of infection, and for gauging the efficacy of the worldwide vaccination effort for COVID-19. In this study, a microchip-based grating-coupled fluorescent plasmonic (GC-FP) assay was used to measure antibody levels that resulted from COVID-19 infection and vaccination. In addition, we measured the relative antibody binding toward antigens from the CoV2 virus variants strains B.1.1.7 (Alpha) and B.1.351 (Beta). Antibody levels against multiple antigens within the SARS CoV2 spike protein were significantly elevated for both vaccinated and infected individuals, while those against the nucleocapsid (N) protein were only elevated for infected individuals. GC-FP was effective for monitoring the IgG-based serological response to vaccination throughout the vaccination sequence and also resolved acute (within hours) increases in antibody levels. A significant decrease in antibody binding to antigens from the B.1.351 variant, but not B.1.1.7, was observed for all vaccinated subjects when measured by GC-FP compared to the 2019 SARS CoV2 antigens. These results were corroborated by competitive enzyme-linked immunosorbent assay (ELISA). Collectively, the findings suggest that GC-FP is a viable, rapid, and accurate method for measuring both overall antibody levels to SARS CoV2 and relative antibody binding to viral variants during infection or vaccination. IMPORTANCE In this work, a novel biosensor technology was used to measure antibody levels that resulted from vaccination against COVID-19 and/or from infection with the virus. Importantly, this approach enables quantification of antibody levels, which can provide information about the timing and level of immune response. Due the multiplexed nature of this approach, antibody binding to both the original 2019 SARS CoV-2 strain and variant strains can be performed simultaneously and in a short (30-min) time frame.

Surveilling cellular vital signs: toward label-free biosensors and real-time viability assays for bioprocessing.

Cell viability is an essential facet of mammalian and microbial bioprocessing. While robust methods of monitoring cellular health remain critically important to biomanufacturing and biofabrication, the complexity of advanced cell culture platforms often poses challenges for conventional viability assays. This review surveys novel approaches to discern the metabolic, morphological, and mechanistic hallmarks of living systems - spanning subcellular and multicellular scales. While fluorescent probes coupled with 3D image analysis generate rapid results with spatiotemporal detail, molecular techniques like viability PCR can distinguish live cells with genetic specificity. Notably, label-free biosensors can detect nuanced attributes of cellular vital signs with single-cell resolution via optical, acoustic, and electrical signals. Ultimately, efforts to integrate these modalities with automation, machine learning, and high-throughput workflows will lead to exciting new vistas across the cell viability landscape.

Disposable photonics for cost-effective clinical bioassays: application to COVID-19 antibody testing.

Decades of research have shown that biosensors using photonic circuits fabricated using CMOS processes can be highly sensitive, selective, and quantitative. Unfortunately, the cost of these sensors combined with the complexity of sample handling systems has limited the use of such sensors in clinical diagnostics. We present a new "disposable photonics" sensor platform in which rice-sized (1 × 4 mm) silicon nitride ring resonator sensor chips are paired with plastic micropillar fluidic cards for sample handling and optical detection. We demonstrate the utility of the platform in the context of detecting human antibodies to SARS-CoV-2, both in convalescent COVID-19 patients and for subjects undergoing vaccination. Given its ability to provide quantitative data on human samples in a simple, low-cost single-use format, we anticipate that this platform will find broad utility in clinical diagnostics for a broad range of assays.

Quantitative multiplexed strategies for human Lyme disease serological testing.

Lyme disease, which is primarily caused by infection with the bacterium Borrelia burgdorferi in the United States or other Borrelia species internationally, presents an ongoing challenge for diagnostics. Serological testing is the primary means of diagnosis but testing approaches differ widely, with varying degrees of sensitivity and specificity. Moreover, there is currently no reliable test to determine disease resolution following treatment. A distinct challenge in Lyme disease diagnostics is the variable patterns of human immune response to a plurality of antigens presented by Borrelia spp. during the infection. Thus, multiplexed testing approaches that capture these patterns and detect serological response against multiple antigens may be the key to prompt, accurate Lyme disease diagnosis. In this review, current state-of-the-art multiplexed diagnostic approaches are presented and compared with respect to their diagnostic accuracy and their potential for monitoring response to treatment.

Lithographically patterned micro-nozzles for controlling fluid flow profiles for drug delivery and in vitro imaging applications.

Precisely controlling delivery of drugs and other reagents is important for intravital microscopy studies. In this work, photolithographic integration of micro-nozzles onto a microfluidic platform was performed to tune the fluid flow profile and depth of penetration into biological tissue mimics. Performance characteristics were measured by correlating the flow rate through the device to the applied pressure and/or delivery of dyes into solution and agarose gel-based phantom tissue. From these results, the implementation of micro-nozzles was demonstrated to significantly improve the lateral dispersion of delivered fluid and increase the depth of penetration into phantom tissue.

Boronate probe-based hydrogen peroxide detection with AlGaN/GaN HEMT sensor.

The results from this study demonstrate the potential of an AlGaN/GaN high electron mobility transistor sensor for the detection of reactive and transient biological molecules such as hydrogen peroxide. A boronate-based fluorescent probe was used with this device to detect the presence of micromolar levels of hydrogen peroxide typically associated with intracellular processes. The real-time electrical response of the high electron mobility transistor sensor showed a gradual decrease in the two-dimensional electron gas current as the reaction proceeded over time. A corresponding increase in the emission intensity was measured from the fluorescent probe with the progression of the reaction. The fluorescence from the boronate probe was used as an indicator to confirm the detection of hydrogen peroxide. These results demonstrate the dynamic measurement capability of AlGaN/GaN high electron mobility transistor sensors in monitoring real-time reactions of reactive oxygen species such as hydrogen peroxide.

Multiplexed detection and quantification of human antibody response to COVID-19 infection using a plasmon enhanced biosensor platform.

The 2019 SARS CoV-2 (COVID-19) pandemic has illustrated the need for rapid and accurate diagnostic tests. In this work, a multiplexed grating-coupled fluorescent plasmonics (GC-FP) biosensor platform was used to rapidly and accurately measure antibodies against COVID-19 in human blood serum and dried blood spot samples. The GC-FP platform measures antibody-antigen binding interactions for multiple targets in a single sample, and has 100% selectivity and sensitivity (n = 23) when measuring serum IgG levels against three COVID-19 antigens (spike S1, spike S1S2, and the nucleocapsid protein). The GC-FP platform yielded a quantitative, linear response for serum samples diluted to as low as 1:1600 dilution. Test results were highly correlated with two commercial COVID-19 antibody tests, including an enzyme linked immunosorbent assay (ELISA) and a Luminex-based microsphere immunoassay. To demonstrate test efficacy with other sample matrices, dried blood spot samples (n = 63) were obtained and evaluated with GC-FP, yielding 100% selectivity and 86.7% sensitivity for diagnosing prior COVID-19 infection. The test was also evaluated for detection of multiple immunoglobulin isotypes, with successful detection of IgM, IgG and IgA antibody-antigen interactions. Last, a machine learning approach was developed to accurately score patient samples for prior COVID-19 infection, using antibody binding data for all three COVID-19 antigens used in the test.

Surface coatings alter transcriptional responses to silver nanoparticles following oral exposure.

Silver nanoparticles (AgNPs) are used in food packaging materials, dental care products and other consumer goods and can result in oral exposure. To determine whether AgNP coatings modulate transcriptional responses to AgNP exposure, we exposed mice orally to 20 nm citrate (cit)-coated AgNPs (cit-AgNPs) or polyvinylpyrrolidone (PVP)-coated AgNPs (PVP-AgNPs) at a 4 mg/kg dose for 7 consecutive days and analyzed changes in the expression of protein-coding genes and long noncoding RNAs (lncRNAs), a new class of regulatory RNAs, in the liver. We identified unique and common expression signatures of protein-coding and lncRNA genes, altered biological processes and signaling pathways, and coding-non-coding gene interactions for cit-AgNPs and PVP-AgNPs. Commonly regulated genes comprised only about 10 and 20 percent of all differentially expressed genes in PVP-AgNP and cit-AgNP exposed mice, respectively. Commonly regulated biological processes included glutathione metabolic process and cellular oxidant detoxification. Commonly regulated pathways included Keap-Nrf2, PPAR, MAPK and IL-6 signaling pathways. The coding-non-coding gene co-expression analysis revealed that protein-coding genes were co-expressed with a variable number of lncRNAs ranging from one to twenty three and may share functional roles with the protein-coding genes. PVP-AgNP exposure induced a more robust transcriptional response than cit-AgNP exposure characterized by more than two-fold higher number of differentially expressed both protein- coding and lncRNA genes. Our data demonstrate that the surface coating strongly modulates the spectrum and the number of differentially expressed genes after oral AgNP exposure. On the other hand, our data suggest that AgNP exposure can alter drug and chemical sensitivity, metabolic homeostasis and cancer risk irrespective of the coating type, warranting further investigations.

Hot Electron Driven Photocatalysis on Plasmon-Resonant Grating Nanostructures.

We demonstrate the hot electron injection of photoexcited carriers in an Ag-based plasmon resonant grating structure. By varying the incident angle of irradiation, sharp dips are observed in the reflectance with p-polarized light (electric field perpendicular to grating lines) when there is wavevector matching between the incident light and the plasmon resonant modes of the grating and no angle dependence is observed with s-polarized light. This configuration enables us to compare photoelectrochemical current produced by plasmon resonant excitation with that of bulk metal interband absorption simply by rotating the polarization of the incident light while keeping all other parameters of the measurement fixed. With 633 nm light, we observed a 12-fold enhancement in the photocurrent (i.e., reaction rate) between resonant and nonresonant polarizations at incident angles of ±7.6° from normal. At 785 nm irradiation, we observed similar resonant profiles to those obtained with 633 nm wavelength light but with a 44-fold enhancement factor. Using 532 nm light, we observed two resonant peaks (with approximately 10× enhancement) in the photocurrent at 19.4° and 28.0° incident angles, each corresponding to higher order modes in the grating with more nodes per period. The lower enhancement factors observed at shorter wavelengths are attributed to interband transitions, which provide a damping mechanism for the plasmon resonance. Finite difference time domain (FDTD) simulations of these grating structures confirm the resonant profiles observed in the angle-dependent spectra of these gratings and provide a detailed picture of the electric field profiles on and off resonance.

A fluorescent plasmonic biochip assay for multiplex screening of diagnostic serum antibody targets in human Lyme disease.

Lyme disease (LD) diagnosis using the current two-tier algorithm is constrained by low sensitivity for early-stage infection and ambiguity in determining treatment response. We recently developed a protein microarray biochip that measures diagnostic serum antibody targets using grating-coupled fluorescent plasmonics (GC-FP) technology. This strategy requires microliters of blood serum to enable multiplexed biomarker screening on a compact surface and generates quantitative results that can be further processed for diagnostic scoring. The GC-FP biochip was used to detect serum antibodies in patients with active and convalescent LD, as well as various negative controls. We hypothesized that the quantitative, high-sensitivity attributes of the GC-FP approach permit: 1) screening of antibody targets predictive for LD status, and 2) development a diagnostic algorithm that is more sensitive, specific, and informative than the standard ELISA and Western blot assays. Notably, our findings led to a diagnostic algorithm that may be more sensitive than the current standard for detecting early LD, while maintaining 100% specificity. We further show that analysis of relative antibody levels to predict disease status, such as in acute and convalescent stages of infection, is possible with a highly sensitive and quantitative platform like GC-FP. The results from this study add to the urgent conversation regarding better diagnostic strategies and more effective treatment for patients affected by tick-borne disease.

Hot electron-driven photocatalysis and transient absorption spectroscopy in plasmon resonant grating structures.

Plasmon resonant grating structures provide an effective platform for distinguishing between the effects of plasmon resonant excitation and bulk metal absorption via interband transitions. By simply rotating the polarization of the incident light, we can switch between resonant excitation and non-resonant excitation, while keeping all other parameters of the measurement constant. With light polarized perpendicular to the lines in the grating (i.e., TE-polarization), the photocatalytic reaction rate (i.e., photocurrent) is measured as the angle of the incident laser light is tuned through the resonance with the grating. Here, hot holes photoexcited in the metal are used to drive the oxygen evolution reaction (OER), producing a measurable photocurrent. Using TE-polarized light, we observe sharp peaks in the photocurrent and sharp dips in the photoreflectance at approximately 9° from normal incidence, which corresponds to the conditions under which there is good wavevector matching between the incident light and the lines in the grating. With light polarized parallel to the grating (i.e., TM), we excite the grating structure non-resonantly and there is no angular dependence in the photocurrent or photoreflectance. In order to quantify the lifetime of these hot carriers, we performed transient absorption spectroscopy of these plasmon resonant grating structures. Here, we observe one feature in the spectra corresponding to interband transitions and another feature associated with the plasmon resonant mode in the grating. Both features decay over a time scale of 1-2 ps. The spectral responses of grating structures fabricated with Ag, Al, and Cu are also presented.

Recent strategies for the diagnosis of early Lyme disease.

Lyme disease (LD) is the most common tick-borne disease in the Northern Hemisphere. As the most prevalent vector-borne disease in the USA, LD affects 300,000 human cases each year. LD is caused by inoculation of the bacterial spirochete, Borrelia burgdorferi sensu lato, from an infected tick. If not treated quickly and completely, the bacteria disseminate from the tick's biting site into multiple organs including the joints, heart, and brain. Thus, the best outcome from medical intervention can be expected with early detection and treatment with antibiotics, prior to multi-organ dissemination. In the absence of a characteristic rash, LD is diagnosed using serological testing involving enzyme-linked immunosorbent assay (ELISA) followed by western blotting, which is collectively known as the two-tier algorithm. These assays detect host antibodies against the bacteria, but are hampered by low sensitivity, which can miss early LD cases. This review discusses the application of some current assays for diagnosing LD clinically, thus providing a foundation for exploring newer techniques being developed in the laboratory for more sensitive detection of early LD.

Simple implantable wireless sensor platform to measure pressure and force.

Smart implants have the potential to enable personalized care regimens for patients. However, the integration of smart implants into daily clinical practice is limited by the size and cost of available sensing technology. Passive resonant sensors are an attractive alternative to traditional sensing technologies because they obviate the need for on-sensor signal conditioning or telemetry and are substantially simpler, smaller, less expensive, and more robust than other sensing methods. We have developed a novel simple, passive sensing platform that is adaptable to a variety of applications. Sensors consist of only two disconnected parallel Archimedean spiral coils and an intervening solid dielectric layer. When exposed to force or pressure, the resonant frequency of the circuit shifts which can be measured wirelessly. We fabricated prototype pressure sensors and force sensors and compared their performance to a lumped parameter model which predicts sensor behavior. The sensors exhibited a linear response (R2 > 0.91) to dynamic changes in pressure or force with excellent sensitivity. Experimental data were within 13.3% and 6.2% of the values predicted by the model for force and pressure respectively. Results demonstrate that the sensors can be adapted to measure various measurands through a span of sensitivities and ranges by appropriate selection of the intervening layer.

Biologically-derived nanomaterials for targeted therapeutic delivery to the brain.

Delivery of imaging agents and pharmaceutical payloads to the central nervous system (CNS) is essential for efficient diagnosis and treatment of brain diseases. However, therapeutic delivery is often restricted by the blood-brain barrier (BBB), which prevents transport of clinical compounds to their region of interest. This review discusses the methods that have been used to avoid or overcome this barrier, presenting the use of biologically-derived nanomaterial systems as an efficient strategy for the diagnosis and treatment of CNS diseases. Biological nanomaterials have many advantages over synthetic systems, including being biodegradable, biocompatible, easily surface functionalised for conjugation of targeting moieties, and are often able to self-assemble. These abilities are discussed in relation to various systems, including liposomes, dendrimers, and viral nanoparticles.

Differential effects of silver nanoparticles on DNA damage and DNA repair gene expression in Ogg1-deficient and wild type mice.

Due to extensive use in consumer goods, it is important to understand the genotoxicity of silver nanoparticles (AgNPs) and identify susceptible populations. 8-Oxoguanine DNA glycosylase 1 (OGG1) excises 8-oxo-7,8-dihydro-2-deoxyguanine (8-oxoG), a pro-mutagenic lesion induced by oxidative stress. To understand whether defects in OGG1 is a possible genetic factor increasing an individual's susceptibly to AgNPs, we determined DNA damage, genome rearrangements, and expression of DNA repair genes in Ogg1-deficient and wild type mice exposed orally to 4 mg/kg of citrate-coated AgNPs over a period of 7 d. DNA damage was examined at 3 and 7 d of exposure and 7 and 14 d post-exposure. AgNPs induced 8-oxoG, double strand breaks (DSBs), chromosomal damage, and DNA deletions in both genotypes. However, 8-oxoG was induced earlier in Ogg1-deficient mice and 8-oxoG levels were higher after 7-d treatment and persisted longer after exposure termination. AgNPs downregulated DNA glycosylases Ogg1, Neil1, and Neil2 in wild type mice, but upregulated Myh, Neil1, and Neil2 glycosylases in Ogg1-deficient mice. Neil1 and Neil2 can repair 8-oxoG. Thus, AgNP-mediated downregulation of DNA glycosylases in wild type mice may contribute to genotoxicity, while upregulation thereof in Ogg1-deficient mice could serve as an adaptive response to AgNP-induced DNA damage. However, our data show that Ogg1 is indispensable for the efficient repair of AgNP-induced damage. In summary, citrate-coated AgNPs are genotoxic in both genotypes and Ogg1 deficiency exacerbates the effect. These data suggest that humans with genetic polymorphisms and mutations in OGG1 may have increased susceptibility to AgNP-mediated DNA damage.

Golgi-Associated Protein Kinase C-ε Is Delivered to Phagocytic Cups: Role of Phosphatidylinositol 4-Phosphate.

Protein kinase C-ε (PKC-ε) at phagocytic cups mediates the membrane fusion necessary for efficient IgG-mediated phagocytosis. The C1B and pseudosubstrate (εPS) domains are necessary and sufficient for this concentration. C1B binds diacylglycerol; the docking partner for εPS is unknown. Liposome assays revealed that the εPS binds phosphatidylinositol 4-phosphate (PI4P) and PI(3,5)P2 Wortmannin, but not LY294002, inhibits PKC-ε concentration at cups and significantly reduces the rate of phagocytosis. As Wortmannin inhibits PI4 kinase, we hypothesized that PI4P mediates the PKC-ε concentration at cups and the rate of phagocytosis. PKC-ε colocalizes with the trans-Golgi network (TGN) PI4P reporter, P4M, suggesting it is tethered at the TGN. Real-time imaging of GFP-PKC-ε-expressing macrophages revealed a loss of Golgi-associated PKC-ε during phagocytosis, consistent with a Golgi-to-phagosome translocation. Treatment with PIK93, a PI4 kinase inhibitor, reduces PKC-ε at both the TGN and the cup, decreases phagocytosis, and prevents the increase in capacitance that accompanies membrane fusion. Finally, expression of the Golgi-directed PI4P phosphatase, hSac1-K2A, recapitulates the PIK93 phenotype, confirming that Golgi-associated PI4P is critical for efficient phagocytosis. Together these data are consistent with a model in which PKC-ε is tethered to the TGN via an εPS-PI4P interaction. The TGN-associated pool of PKC-ε concentrates at the phagocytic cup where it mediates the membrane fusion necessary for phagocytosis. The novelty of these data lies in the demonstration that εPS binds PI4P and PI(3,5)P2 and that PI4P is necessary for PKC-ε localization at the TGN, its translocation to the phagocytic cup, and the membrane fusion required for efficient Fc [γ] receptor-mediated phagocytosis.