SURFACE ACOUSTIC WAVE (SAW)-ENHANCED SURFACE PLASMON RESONANCE (SPR) BIOSENSOR

The aim of this master thesis work was the realization of a biosensor based on surface plasmon resonance (SPR) which was integrated with surface acoustic wave (SAW)-driven microfluidics. Over the last 15 years SAW-induced mixers for microfluidic devices have been developed owing to their fast mixing capabilities. Meanwhile, SPR sensors have also been developed because of their high reliability and quantitative real-time measurements. Following the Drude model of electrical conduction, surface plasmons (SPs) can be considered as propagating electron density waves occurring at the interface between a metal and a dielectric and can alternatively be viewed as electromag- netic waves that are strongly bound to this interface. The resonance condition for SP excitation varies with the refractive index of the dielectric in the proximity (about 200 nm for visible light) of the surface of the metal film supporting the SP. A change in the resonance condition measured with an optical setup can be used to detect changes in the refractive index. SPR sensing is particularly useful for biological applications. By functionalizing the SPR sensor surface it is pos- sible to detect binding events in real-time and quantify the concentration of the analyte to be studied with high reliability. SPR biosensors have applications in numerous important fields including medical diagnostics, environmental mon- itoring, and food safety and security with resolution as low as 10 − 7 refractive index units (RIU) (§1). Lab-on-a-chip (LOC) devices are typically being developed for use in the life sciences and diagnostics and represent a fast moving field in which efforts are being made in order to increase portability and efficiency. Microfluidic systems are characterized by small Reynolds numbers which indicates that fluid flow is in general laminar. Efficient mixing is a challenge at these scales that can, how- ever, be overcome with the use of SAW-induced streaming. SAWs are mechanical oscillations which propagate along the surface of a given crystal. In piezoelectric materials they can be generated using interdigitated transducers (IDT), which are fabricated using thin-film metal deposition. When a SAW comes into con- tact with the edge of a liquid in its path, the acoustic energy diffracts into the fluid due to the mismatch between the sound velocity in the substrate and the liquid, causing a longitudinal pressure wave front that gives rise to the acoustic streaming. This phenomenon can be exploited to efficiently mix solutions with 1times that are significantly shorter than without SAWs (§2). By using micro- and nano- fabrication techniques (§3.1) a biosensor was de- veloped where SAW-driven active mixing and SPR sensing were integrated onto a common substrate. The optical setup (§3.4) was based on wavelength modula- tion and Kretschmann geometry where a polychromatic light is totally reflected through a high refractive index prism (on which the chip is placed). A spectrom- eter was used to analyze the reflected spectra. The SPR surface was functional- ized in order to study a biotin-streptavidin system (§3.3). SPR was first character- ized in droplets and then in polydimethylsiloxan (PDMS) microchannels (§3.2). By adding an IDT onto the chip it was possible to induce acoustic streaming in the channel while the biotin functionalization or the biotin-streptavidin event occurred. SAW was characterized by using a laser doppler vibrometer and a vector network analyzer. Owing to the chip design it was possible to decouple the two effects induced by SAW in the microchannel: streaming and heating. A thermocamera was used to study the second effect. The effect of the SAWs was studied both on the functionalization process and the streptavidin-biotin binding (§4). SAW streaming resulted in better surface functionalization than in the case without SAW. The signal due to the functionalization of gold with biotin was about 4.4 times higher than the signal detected without SAW-assisted functionalization. It is possible, then, to conclude that SAW streaming increases the probability that the biotin will be in contact with the gold surface and attach to it. Preliminary data also suggest better streptavidin biosensing than control device. The biosensor made for this master thesis work was the first SAW-driven mi- crofluidic device with SPR integrated on the same substrate. It showed promis- ing results that might be exploited for improving sensitivity and limit of detec- tion of SPR biosensors

Polydimethylsiloxane (PDMS) irreversible bonding to untreated plastics and metals for microfluidics applications

In order to properly manipulate liquids into microfluidic networks, an accurate sealing of the device is of paramount importance. Polydimethylsiloxane (PDMS) is ubiquitously used for fabricating microfluidic components, owing to its low cost, easy and fast fabrication, and optical transparency. However, PDMS is characterized by low surface energy, making its bonding to many substrates not trivial. Here is presented a versatile technique for PDMS microchannel bonding on untreated plastic and metal surfaces. First, the PDMS surface is functionalized with (3-aminopropyl) triethoxysilane (APTES) for further cross-linking with epoxy groups. Then, the PDMS-APTES surface is coated with Norland Optical Adhesive 74 (NOA74). Finally, the PDMS-APTES-NOA74 is put in contact with the target material and the glue is cured under a UV light. In order to characterize the bonding strength, a complete PDMS-on-gold microfluidic device is fabricated and tested with increasing injection pressures. Different liquids and a gas (nitrogen) are applied without leakage up to 2 bars, a value comparable to the one reported for the standard glass-PDMS bonding through plasma oxygen activation. The same technique is then successfully replicated with other nonmetallic substrates of interest for microfluidics, i.e., glass, poly(methyl methacrylate), polystyrene, polyethylene terephthalate, cyclic olefin copolymer, demonstrating its great versatility and potential for, but not limited to, microfluidic applications and LOC engineering

Full-SAW Microfluidics-Based Lab-on-a- Chip for Biosensing

Many approaches to diagnostic testing remain decades old. Well-established biosensing technologies (e.g., enzyme-linked immunosorbent assays and radio-immunoassays) typically cannot fulfill the requirements of portability and ease of use necessary for point-of-care purposes. Several alternatives have been proposed (e.g., quartz-crystal-microbalances, electrochemical sensors, cantilevers, and surfaceplasmon- resonance sensors) but often lack high performance or still necessitate bulk ancillary instruments to operate. Here we present a highly sensitive, versatile, and easily integrable micro uidic lab-on-a-chip (LoC) for biosensing, fully based on surface acoustic waves (SAWs). By using ultra-high-frequency resonatorbiosensors, we showthat it is possible to perform highly sensitive assays in complex media. This all-electrical readout platform is benchmarked with the biotin-streptavidin binding in presence of non-specific binding proteins (serum albumin) at physiological concentration. The benchmark experiments were performed with the idea of mimicking a biological fluid, in which other molecular species at high concentration are present together with the analytes. We demonstrate that this LoC can detect sub-nanomolar concentrations of analytes in complex media. As a comparison with similar acoustic-wave-based systems, this full-SAW platform outperforms the standard commercial gravimetric sensors (i.e., quartz-crystal-microbalances) and the more common Love-SAW biosensors. This full-SAW LoC could be further developed for the detection of biomarkers in biological fluids

Eureka Township Envisioning Task Force Report: Exploring the Possibilities.

Supported by the Minnesota Office of Environmental Assistance; Concern, Inc.; Laura Jane Musser Fund; Carolyn Foundation; Center for Urban and Regional Affairs, University of Minnesota; and Members of 1000 Friends of Minnesota

Human, donkey and cow milk differently affects energy efficiency and inflammatory state by modulating mitochondrial function and gut microbiota

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Increase of Parkin and ATG5 plasmatic levels following perinatal hypoxic‐ischemic encephalopathy

Brain injury at birth is an important cause of neurological and behavioral disorders. Hypoxic‐ischemic encephalopathy (HIE) is a critical cerebral event occurring acutely or chronically at birth with high mortality and morbidity in newborns. Therapeutic strategies for the prevention of brain damage are still unknown, and the only medical intervention for newborns with moderate‐to‐severe HIE is therapeutic hypothermia (TH). Although the neurological outcome depends on the severity of the initial insult, emerging evidence suggests that infants with mild HIE who are not treated with TH have an increased risk for neurodevelopmental impairment; in the current clinical setting, there are no specific or validated biomarkers that can be used to both correlate the severity of the hypoxic insult at birth and monitor the trend in the insult over time. The aim of this work was to examine the presence of autophagic and mitophagic proteins in bodily fluids, to increase knowledge of what, early at birth, can inform therapeutic strategies in the first hours of life. This is a prospective multicentric study carried out from April 2019 to April 2020 in eight third‐level neonatal intensive care units. All participants have been subjected to the plasma levels quantification of both Parkin (a protein involved in mitophagy) and ATG5 (involved in autophagy). These findings show that Parkin and ATG5 levels are related to hypoxic‐ischemic insult and are reliable also at birth. These observations suggest a great potential diagnostic value for Parkin evaluation in the first 6 h of life

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Surface acoustic wave (SAW) technology for microfluidic lab-on-chips (LoCs) and biosensors

In the middle of the fourth industry revolution the necessity of intelligent manufacturing and sensors plays an important role and pulls the research activity of these days. In particular, smart objects able to sense, act, and behave within smart environments are suitable tools to make this revolution evolve even further. More efficient devices (in terms of costs, time and results) and data generated at all levels, from industry production processes to people health monitoring, are desirable to improve life quality. This goal would not be achieved without smart lab-on-chips (LoCs) and sensors. Over the last decades surface acoustic wave (SAW) technology has been studied and exploited to realize such smart devices. Main advantages over standard microfluidic fluids manipulators and sensors are the high portability of these devices, their all-electrical readout systems, their fabrication scalability and their application versatility. In this context I developed my Ph.D. research activity, by designing, fabricating, characterizing and testing new SAW-based devices for LoC and sensing applications. I exploited both Rayleigh and Love SAWs for this purpose, exploring different designs and working frequencies and obtaining several encouraging results. With these SAW devices I demonstrated for the first time that it is possible to enhance cells proliferation or gold functionalization kinetics and efficiency. One of the main advantages of these devices is that they are totally integrable with other ones and compatible with standard laboratories protocols. Moving for the first time to ultra-high frequency (UHF), I realized SAW biosensors with lower limit of detection than standard commercial acoustic sensors and higher sensitivity and dynamic range than low-frequency SAW sensors. The devices were tested with benchmark analytes and cells after being characterized in details with microscopes, a laser Doppler vibrometer, a vector network analyzer, an infrared camera and by means of micro-particle image velocimetry. Given these results, the devices here presented are promising in the light of the development of versatile, portable, and sensitive SAW-based devices for more efficient production of functionalized materials and cells, smart diagnostics and monitoring of diseases, food and air quality. They have the potential to contribute to the improvement of daily life in the vision of the internet of things devices, for a smarter and more efficient \u201cfuture\u201d world

Five Ps (Policies, Practices, Power structures, Places; and People): A Framework to Analyze Systemic Inequalities

This chart is part of a framework to establish institutional equity and is part of the following National Science Foundation grant project: The Spaces of Empowerment for Equity and Diversity: Advancement Through Access (SEE-DATA) project at Portland State University (PSU) aims to identify, understand, and improve the workplace experiences and retention of faculty in STEM fields who have been traditionally minoritized and marginalized based on gender, race/ethnicity, and other intersectional identities (e.g., sexual orientation, disability, socioeconomic status, national origin, immigrant status). The project will collect, analyze, and map data about faculty’s experiences at PSU to inform programs and policies that seek to foster the retention and flourishing of a faculty that more closely resembles the diverse student body at PSU. It is anticipated that the SEE-DATA project will significantly contribute to improving institutional equity.SEE-DATA will take an intersectional approach to data collection, management, analysis, visualization, and dissemination by combining qualitative, quantitative, and socio-spatial data, techniques, and mapping tools with the goal of conveying more nuanced understandings of the equity landscape and “ecosystem” for diverse faculty members than has been established to date elsewhere. The scope of the methodology that the project will develop will be applicable to STEM departments across the university and to other institutions. The project’s strengths-based self-assessment methodologies will contribute to a toolkit for capturing and visualizing the dynamic interplay between the multiple lived identities of STEM faculty as they are manifested in the institutional landscape, thus supporting ADVANCE goals for expanding intersectional equity strategies and interventions. This project addresses limits in extant sources of data (e.g., numerical counts, climate surveys) on the intersectional factors affecting academic STEM recruitment, workplace experiences, retention, and promotion. Outcomes will be expected to advance a clearer and deeper understanding of individual empowerment pathways and institutional systemic change levers in advancing faculty equity in STEM. Knowledge generated will be disseminated via avenues such as a project webpage, public seminars, and conferences geared to professional and general audiences, as well as through networks within PSU, at other colleges/universities, with professional organizations nationally, and via the ADVANCE Resource Coordination Network (ARC) and StratEGIC website. The NSF ADVANCE program is designed to foster gender equity through a focus on the identification and elimination of organizational barriers that impede the full participation and advancement of diverse faculty in academic institutions. Organizational barriers that inhibit equity may exist in policies, processes, practices, and the organizational culture and climate. ADVANCE Catalyst awards provide support for institutional equity assessments and the development of five-year faculty equity strategic plans at an academic, non-profit institution of higher education.This award reflects NSF\u27s statutory mission and has been deemed worthy of support through evaluation using the Foundation\u27s intellectual merit and broader impacts review criteria

Eureka Township Envisioning Task Force Report: Summary Report

Supported by the Minnesota Office of Environmental Assistance; Concern, Inc.; Laura Jane Musser Fund; Carolyn Foundation; Center for Urban and Regional Affairs, University of Minnesota; and Members of 1000 Friends of Minnesota