Samuel K. Sia

Background: HIV pre-exposure prophylaxis (PrEP) is underused by cis- and transgender women despite a significant HIV burden. Smartphone technologies are promising tools to support HIV prevention but have yet to be assessed in women. Objective: We conducted a 12-month feasibility study to assess the use and acceptability of a mobile phone app, SmartPrEP, designed to support PrEP adherence and HIV self- and partner-testing among women living in an area of elevated HIV burden in New York City. Methods: Nonpregnant adult cisgender and transgender women who met US PrEP eligibility criteria and were PrEP naïve, reported PrEP use for 4 HIV risk behaviors in the past 6 months, with 58% (23/40) reporting anal or vaginal sex with more than 1 partner. Over the course of the study, although 8 participants withdrew early, and 14 were lost to follow-up, there were 2 pregnancies and 1 HIV seroconversion. PrEP adherence was low, with 80% (32/40) recording 3 doses per week compared to 20% (8/40). In total, 4 participants conducted HIV self- or partner-testing using SmartPrEP during study follow-up. App acceptability assessed at month 12 was moderate to high (median score 3.71 of max 5, IQR 3.47‐4.16). Conclusions: Despite consistently rating the app as acceptable and receiving quarterly HIV testing and counseling, most participants did not achieve optimal PrEP adherence, demonstrating the limitations of this mobile health app among women at elevated risk of HIV. Active navigation and strategies to address gaps in risk perception among women will remain critical, as new, long-acting formulations of PrEP become available.

PlasmaLIFT enables automated plasma separation from milliliters of whole blood by integrating immunomagnetic red blood cell depletion with dual-membrane filtration.

New approaches are needed to screen anti-cancer drugs that can target specific subpopulations of tumor cells.

Decentralized molecular detection of pathogens remains an important goal for public health. Although polymerase chain reaction (PCR) remains the gold‐standard molecular detection method, thermocycling using Peltier heaters presents challenges in decentralized settings. Recent work has demonstrated plasmonic PCR, where nanomaterials on a surface or nanoparticles in solution heat upon stimulation by light, as a promising method for rapid thermocycling. Heating of a solution via nanoparticles suspended in solution has been demonstrated in PCR tubes, but not on microfluidic chips. We developed a volumetric, microfluidic plasmonic reverse transcription (RT)‐PCR method. A microfluidic chip is fabricated with an integrated thermocouple to measure internal temperature, feeding into a proportional‐integral‐derivative (PID) algorithm that modulates an infrared LED for closed‐loop control. Gold nanorods are dispersed in solution with RT‐PCR reagents. We created an instrument for plasmonic RT‐PCR using an infrared LED for heating, fan for cooling, and fluorometer for end‐point fluorescence detection. Rapid thermocycling and amplification of SARS‐CoV‐2 within 16 min (5 min for RT, 45 cycles in 11 min) is achieved. This paper demonstrates volumetric, plasmonic PCR in a microfluidic chip, using an integrated thermocouple for closed‐loop control. This work points to the promise of using microfluidics and nanomaterials to achieve rapid, compact detection of pathogens in decentralized settings.

Cuffless noninvasive blood pressure (BP) measurement could enable early unobtrusive detection of abnormal BP patterns, but when the sensor is placed on a location away from heart level (such as the arm), its accuracy is compromised by variations in the position of the sensor relative to heart level; such positional variations produce hydrostatic pressure changes that can cause swings in tens of mmHg in the measured BP if uncorrected. A standard method to correct for changes in hydrostatic pressure makes use of a bulky fluid-filled tube connecting heart level to the sensor. Here, we present an alternative method to correct for variations in hydrostatic pressure using unobtrusive wearable inertial sensors. This method, called IMU-Track, analyzes motion information with a deep learning model; for sensors placed on the arm, IMU-Track calculates parameterized arm-pose coordinates, which are then used to correct the measured BP. We demonstrated IMU-Track for BP measurements derived from pulse transit time, acquired using electrocardiography and finger photoplethysmography, with validation data collected across 20 participants. Across these participants, for the hand heights of 25 cm below or above the heart, mean absolute errors were reduced for systolic BP from 13.5 ± 1.1 and 9.6 ± 1.1 to 5.9 ± 0.7 and 5.9 ± 0.5 mmHg, respectively, and were reduced for diastolic BP from 15.0 ± 1.0 and 11.5 ± 1.5 to 6.8 ± 0.5 and 7.8 ± 0.8, respectively. On a commercial smartphone, the arm-tracking inference time was ~134 ms, sufficiently fast for real-time hydrostatic pressure correction. This method for correcting hydrostatic pressure may enable accurate passive cuffless BP monitors placed at positions away from heart level that accommodate everyday movements.

This study presents an in vivo optical hydrogel microneedle platform that measures levels of analytes in interstitial fluid. The platform builds on a previously published technique for molding hydrogel microneedles by developing a composite hydrogel (i.e., PEGDA and polyacrylamide) that is sufficiently stiff to penetrate skin in the hydrated state and whose fluorescence changes dynamically–via a conjugated aptamer–depending on level of analyte. In a demonstration relevant to hypercalcemia, the hydrogel microneedle distinguished varying concentrations of calcium (within a range of 0 to 2 mM, which spans physiologically meaningful variations for hypoparathyroidism) within 10 minutes. In rats, a compact CMOS sensor measuring fluorescence from microneedles distinguished low hypercalcemic (1.7 mM) from high hypercalcemic (2.3 mM) ionized calcium levels as determined from reference blood measurements. Overall, this work demonstrates in vivo feasibility of a concept–which we call mPatch–for an optical hydrogel microneedle to measure small changes in levels of analytes in interstitial fluid, which does not rely on extraction of interstitial fluid out of the dermis.

This study presents an in vivo optical hydrogel microneedle platform that measures levels of analytes in interstitial fluid. The platform builds on a previously published technique for molding hydrogel microneedles by developing a composite hydrogel (i.e., PEGDA and polyacrylamide) that is sufficiently stiff to penetrate skin in the hydrated state and whose fluorescence changes dynamically–via a conjugated aptamer–depending on level of analyte. In a demonstration relevant to hypercalcemia, the hydrogel microneedle distinguished varying concentrations of calcium (within a range of 0 to 2 mM, which spans physiologically meaningful variations for hypoparathyroidism) within 10 minutes. In rats, a compact CMOS sensor measuring fluorescence from microneedles distinguished low hypercalcemic (1.7 mM) from high hypercalcemic (2.3 mM) ionized calcium levels as determined from reference blood measurements. Overall, this work demonstrates in vivo feasibility of a concept–which we call mPatch–for an optical hydrogel microneedle to measure small changes in levels of analytes in interstitial fluid, which does not rely on extraction of interstitial fluid out of the dermis.

Sample preparation presents a major challenge in point-of-care (POC) diagnostic assays, including ones requiring whole blood as the starting specimen. This study presents an integrated sample preparation device – which we call PRECISE – that performs both plasma separation and nucleic acid extraction, enabling streamlined sample preparation from whole blood requiring only a commercially available blood collection tool and a syringe, and no other external equipment or electricity. Plasma separation is performed using a dual-membrane filter (which filters out blood components while limiting membrane clogging) integrated into the cartridge, and nucleic acid extraction is performed by users moving magnets (to mix the samples, and along a guided track). The plasma filtration demonstrated recovery on par with lab-based centrifugation, and the extraction module showed performance similar to benchtop-based magnetic bead extraction. A sample-to-result demonstration on 50 μL of whole blood spiked with virions of hepatitis C virus (HCV), operating the PRECISE cartridge in 16 minutes followed by benchtop PCR, showed a limit of detection (∼6770 IU mL⁻¹) on the order of the minimal requirements of target product profile for POC HCV detection. Future work on the PRECISE cartridge, building on POC accessibility and fast sample preparation demonstrated in this work, may enable detection of bloodborne pathogens from whole-blood specimens collected at the POC.

Chronic wounds affect ~2% of the U.S. population and increase risks of amputation and mortality. Unfortunately, treatments for such wounds are often expensive, complex, and only moderately effective. Electrotherapy represents a cost-effective treatment; however, its reliance on bulky equipment limits its clinical use. Here, we introduce water-powered, electronics-free dressings (WPEDs) that offer a unique solution to this issue. The WPED performs even under harsh conditions—situations wherein many present treatments fail. It uses a flexible, biocompatible magnesium-silver/silver chloride battery and a pair of stimulation electrodes; upon the addition of water, the battery creates a radial electric field. Experiments in diabetic mice confirm the WPED’s ability to accelerate wound closure and promote healing by increasing epidermal thickness, modulating inflammation, and promoting angiogenesis. Across preclinical wound models, the WPED-treated group heals faster than the control with wound closure rates comparable to treatments requiring expensive biologics and/or complex electronics. The results demonstrate the WPED’s potential as an effective and more practical wound treatment dressing.