Structure Property Relationship of Micellar Waterborne Poly(Urethane-Urea): Tunable Mechanical Properties and Controlled Release Profiles with Amphiphilic Triblock Copolymers.

Waterborne polyurethane (WPU) has attracted significant interest as a promising alternative to solvent-based polyurethane (SPU) due to its positive impact on safety and sustainability. However, significant limitations of WPU, such as its weaker mechanical strength, limit its ability to replace SPU. Triblock amphiphilic diols are promising materials to enhance the performance of WPU due to their well-defined hydrophobic-hydrophilic structures. Yet, our understanding of the relationship between the hydrophobic-hydrophilic arrangements of triblock amphiphilic diols and the physical properties of WPU remains limited. In this study, we show that by controlling the micellar structure of WPU in aqueous solution via the introduction of triblock amphiphilic diols, the postcuring efficiency and the resulting mechanical strength of WPU can be significantly enhanced. Small-angle neutron scattering confirmed the microstructure and spatial distribution of hydrophilic and hydrophobic segments in the engineered WPU micelles. In addition, we show that the control of the WPU micellar structure through triblock amphiphilic diols renders WPU attractive in the applications of controlled release, such as drug delivery. Here, curcumin was used as a model hydrophobic drug, and the drug release behavior from WPU-micellar-based drug delivery systems was characterized. It was found that curcumin-loaded WPU drug delivery systems were highly biocompatible and exhibited antibacterial properties in vitro. Furthermore, the sustained release profile of the drug was found to be dependent on the structure of the triblock amphiphilic diols, suggesting the possibility of controlling the drug release profile via the selection of triblock amphiphilic diols. This work shows that by shedding light on the structure-property relationship of triblock amphiphilic diol-containing WPU micelles, we may enhance the applicability of WPU systems and move closer to realizing their promising potential in real-life applications.

A wireless, skin-interfaced biosensor for cerebral hemodynamic monitoring in pediatric care.

The standard of clinical care in many pediatric and neonatal neurocritical care units involves continuous monitoring of cerebral hemodynamics using hard-wired devices that physically adhere to the skin and connect to base stations that commonly mount on an adjacent wall or stand. Risks of iatrogenic skin injuries associated with adhesives that bond such systems to the skin and entanglements of the patients and/or the healthcare professionals with the wires can impede clinical procedures and natural movements that are critical to the care, development, and recovery of pediatric patients. This paper presents a wireless, miniaturized, and mechanically soft, flexible device that supports measurements quantitatively comparable to existing clinical standards. The system features a multiphotodiode array and pair of light-emitting diodes for simultaneous monitoring of systemic and cerebral hemodynamics, with ability to measure cerebral oxygenation, heart rate, peripheral oxygenation, and potentially cerebral pulse pressure and vascular tone, through the utilization of multiwavelength reflectance-mode photoplethysmography and functional near-infrared spectroscopy. Monte Carlo optical simulations define the tissue-probing depths for source-detector distances and operating wavelengths of these systems using magnetic resonance images of the head of a representative pediatric patient to define the relevant geometries. Clinical studies on pediatric subjects with and without congenital central hypoventilation syndrome validate the feasibility for using this system in operating hospitals and define its advantages relative to established technologies. This platform has the potential to substantially enhance the quality of pediatric care across a wide range of conditions and use scenarios, not only in advanced hospital settings but also in clinics of lower- and middle-income countries.

A Wireless Near-Infrared Spectroscopy Device for Flap Monitoring: Proof of Concept in a Porcine Musculocutaneous Flap Model.

BACKGROUND: Current near-infrared spectroscopy (NIRS)-based systems for continuous flap monitoring are highly sensitive for detecting malperfusion. However, the clinical utility and user experience are limited by the wired connection between the sensor and bedside console. This wire leads to instability of the flap-sensor interface and may cause false alarms. METHODS: We present a novel wearable wireless NIRS sensor for continuous fasciocutaneous free flap monitoring. This waterproof silicone-encapsulated Bluetooth-enabled device contains two light-emitting diodes and two photodetectors in addition to a battery sufficient for 5 days of uninterrupted function. This novel device was compared with a ViOptix T.Ox monitor in a porcine rectus abdominus myocutaneous flap model of arterial and venous occlusions. RESULTS: Devices were tested in four flaps using three animals. Both devices produced very similar tissue oxygen saturation (StO2) tracings throughout the vascular clamping events, with obvious and parallel changes occurring on arterial clamping, arterial release, venous clamping, and venous release. Small interdevice variations in absolute StO2 value readings and magnitude of change were observed. The normalized cross-correlation at zero lag describing correspondence between the novel NIRS and T.Ox devices was >0.99 in each trial. CONCLUSION: The wireless NIRS flap monitor is capable of detecting StO2 changes resultant from arterial vascular occlusive events. In this porcine flap model, the functionality of this novel sensor closely mirrored that of the T.Ox wired platform. This device is waterproof, highly adhesive, skin conforming, and has sufficient battery life to function for 5 days. Clinical testing is necessary to determine if this wireless functionality translates into fewer false-positive alarms and a better user experience.

Kangaroo father care: A pilot feasibility study of physiologic, biologic, and psychosocial measures to capture the effects of father-infant and mother-infant skin-to-skin contact in the Neonatal Intensive Care Unit.

Robust literature supports the positive effects of kangaroo mother care (KMC) on infant physiologic stability and parent-infant bonding in the Neonatal Intensive Care Unit (NICU). Comparatively little is known about kangaroo father care (KFC) in the NICU, and KFC implementation has been limited. Our pilot feasibility study objective was to examine KFC effects on premature infants and fathers as compared to KMC. Parents of preterm NICU infants independently completed a 90-min Kangaroo Care (KC) session on consecutive days. Infant heart rate variability (HRV) and apnea/periodicity measures were compared (pre-KC to KC; KFC to KMC). Additionally, we assessed the feasibility of administering three psychosocial questionnaires to fathers and mothers in the NICU and after discharge. Ten preterm infants completed 20 KC sessions (334/7 -374/7  weeks post-menstrual age). Results demonstrated similar infant physiologic responses between KMC and KFC, including significant differences in measures of HRV (p < .05) between KC and non-KC periods. Eighty-eight percentage of questionnaires administered were completed, supporting the utilization of these instruments in future research of this population. If confirmed, these preliminary results identify an opportunity to objectively assess KFC effects, supporting the development of empirically based KFC programs benefitting NICU families.

Prolonged Duration Local Anesthesia by Combined Delivery of Capsaicin- and Tetrodotoxin-Loaded Liposomes.

BACKGROUND: Capsaicin, the active component of chili peppers, can produce sensory-selective peripheral nerve blockade. Coadministration of capsaicin and tetrodotoxin, a site-1 sodium channel blocker, can achieve a synergistic effect on duration of nerve blocks. However, capsaicin can be neurotoxic, and tetrodotoxin can cause systemic toxicity. We evaluated whether codelivery of capsaicin and tetrodotoxin liposomes can achieve prolonged local anesthesia without local or systemic toxicity. METHODS: Capsaicin- and tetrodotoxin-loaded liposomes were developed. Male Sprague-Dawley rats were injected at the sciatic nerve with free capsaicin, capsaicin liposomes, free tetrodotoxin, tetrodotoxin liposomes, and blank liposomes, singly or in combination. Sensory and motor nerve blocks were assessed by a modified hotplate test and a weight-bearing test, respectively. Local toxicity was assessed by histologic scoring of tissues at the injection sites and transmission electron microscopic examination of the sciatic nerves. Systemic toxicity was assessed by rates of contralateral nerve deficits and/or mortality. RESULTS: The combination of capsaicin liposomes and tetrodotoxin liposomes achieved a mean duration of sensory block of 18.2 hours (3.8 hours) [mean (SD)], far longer than that from capsaicin liposomes [0.4 hours (0.5 hours)] (P < .001) or tetrodotoxin liposomes [0.4 hours (0.7 hours)] (P < .001) given separately with or without the second drug in free solution. This combination caused minimal myotoxicity and muscle inflammation, and there were no changes in the percentage or diameter of unmyelinated axons. There was no systemic toxicity. CONCLUSIONS: The combination of encapsulated tetrodotoxin and capsaicin achieved marked prolongation of nerve block. This combination did not cause detectable local or systemic toxicity. Capsaicin may be useful for its synergistic effects on other formulations even when used in very small, safe quantities.

Prolonged Duration Local Anesthesia Using Liposomal Bupivacaine Combined With Liposomal Dexamethasone and Dexmedetomidine.

BACKGROUND: The relatively short duration of effect of local anesthetics has been addressed by encapsulation in drug delivery systems. Codelivery with a single compound that produces an adjuvant effect on nerve block but without intrinsic local anesthetic properties can further prolong the nerve block effect. Here, we investigated whether codelivery of more than 1 encapsulated adjuvant compound can further enhance nerve blockade. METHODS: Liposomes loaded with bupivacaine (Bup), dexamethasone phosphate (DexP), or dexmedetomidine (DMED) were synthesized and its in vitro drug release profiles were determined. Animals (Sprague-Dawley rats) were injected with liposomal Bup (Lipo-Bup) and adjuvants at the sciatic nerve and underwent a modified hot plate test to assess the degree of nerve block. The duration of block was monitored and the tissue reaction was assessed. RESULTS: Coinjection of Lipo-Bup with liposomal DexP (Lipo-DexP) and liposomal DMED (Lipo-DMED) prolonged the duration of sciatic nerve block 2.9-fold compared to Lipo-Bup alone (95% confidence interval, 1.9- to 3.9-fold). The duration of the block using this combination was significantly increased to 16.2 ± 3.5 hours compared to Lipo-Bup with a single liposomal adjuvant (8.7 ± 2.4 hours with Lipo-DMED, P = .006 and 9.9 ± 5.9 hours with Lipo-DexP, P = .008). The coinjection of Lipo-Bup with liposomal adjuvants decreased tissue inflammation (P = .014) but did not have a significant effect on myotoxicity when compared to Lipo-Bup alone. Coinjection of Lipo-Bup with unencapsulated adjuvants prolonged the duration of nerve block as well (25.0 ± 6.3 hours; P < .001) however was accompanied by systemic side effects. CONCLUSIONS: Codelivery of Lipo-DexP and Lipo-DMED enhanced the efficacy of Lipo-Bup. This benefit was also seen with codelivery of both adjuvant molecules in the unencapsulated state, but with marked systemic toxicity.

Repeatable and adjustable on-demand sciatic nerve block with phototriggerable liposomes.

Pain management would be greatly enhanced by a formulation that would provide local anesthesia at the time desired by patients and with the desired intensity and duration. To this end, we have developed near-infrared (NIR) light-triggered liposomes to provide on-demand adjustable local anesthesia. The liposomes contained tetrodotoxin (TTX), which has ultrapotent local anesthetic properties. They were made photo-labile by encapsulation of a NIR-triggerable photosensitizer; irradiation at 730 nm led to peroxidation of liposomal lipids, allowing drug release. In vitro, 5.6% of TTX was released upon NIR irradiation, which could be repeated a second time. The formulations were not cytotoxic in cell culture. In vivo, injection of liposomes containing TTX and the photosensitizer caused an initial nerve block lasting 13.5 ± 3.1 h. Additional periods of nerve block could be induced by irradiation at 730 nm. The timing, intensity, and duration of nerve blockade could be controlled by adjusting the timing, irradiance, and duration of irradiation. Tissue reaction to this formulation and the associated irradiation was benign.

Enhanced Triggering of Local Anesthetic Particles by Photosensitization and Photothermal Effect Using a Common Wavelength.

On-demand pain relief systems would be very helpful additions to the armamentarium of pain management. Near-infrared triggered drug delivery systems have demonstrated the potential to provide such care. However, challenges remain in making such systems as stimulus-sensitive as possible, to enhance depth of tissue penetration, repeatability of triggering, and safety. Here we developed liposomes containing the local anesthetic tetrodotoxin and also containing a photosensitizer and gold nanorods that were excitable at the same near-infrared wavelength. The combination of triggering mechanisms enhanced the photosensitivity and repeatability of the system in vitro when compared with liposomes with a single photoresponsive component. In vivo, on-demand local anesthesia could be induced with a low irradiance and short irradiation duration, and liposomes containing both photosensitizer and gold nanorods were more effective than those containing just one photoresponsive component. Tissue reaction was benign.

Ultrasensitive Phototriggered Local Anesthesia.

An injectable local anesthetic producing repeatable on-demand nerve block would be desirable for pain management. Here we present a phototriggerable device to achieve repeatable and adjustable on-demand local anesthesia in superficial or deep tissues, consisting of gold nanorods attached to low temperature sensitive liposomes (LTSL). The particles were loaded with tetrodotoxin and dexmedetomidine. Near-infrared light (NIR, 808 nm, continuous wave) could heat gold nanorods at low fluence (short duration and low irradiance), leading to rapid release of payload. In vivo, 1-2 min of irradiation at ≤272 mW/cm2 produced repeatable and adjustable on-demand infiltration anesthesia or sciatic nerve blockade with minimal toxicity. The nerve block intensity and duration correlated with the irradiance and duration of the applied light.

Synthetic ligand-coated magnetic nanoparticles for microfluidic bacterial separation from blood.

Bacterial sepsis is a serious clinical condition that can lead to multiple organ dysfunction and death despite timely treatment with antibiotics and fluid resuscitation. We have developed an approach to clearing bacteria and endotoxin from the bloodstream, using magnetic nanoparticles (MNPs) modified with bis-Zn-DPA, a synthetic ligand that binds to both Gram-positive and Gram-negative bacteria. Magnetic microfluidic devices were used to remove MNPs bound to Escherichia coli , a Gram-negative bacterium commonly implicated in bacterial sepsis, from bovine whole blood at flows as high as 60 mL/h, resulting in almost 100% clearance. Such devices could be adapted to clear bacteria from septicemic patients.

Miniaturized therapeutic systems for ultrasound-modulated drug delivery to the central and peripheral nervous system.

Ultrasound is a promising technology to address challenges in drug delivery, including limited drug penetration across physiological barriers and ineffective targeting. Here we provide an overview of the significant advances made in recent years in overcoming technical and pharmacological barriers using ultrasound-assisted drug delivery to the central and peripheral nervous system. We commence by exploring the fundamental principles of ultrasound physics and its interaction with tissue. The mechanisms of ultrasonic-enhanced drug delivery are examined, as well as the relevant tissue barriers. We highlight drug transport through such tissue barriers utilizing insonation alone, in combination with ultrasound contrast agents (e.g., microbubbles), and through innovative particulate drug delivery systems. Furthermore, we review advances in systems and devices for providing therapeutic ultrasound, as their practicality and accessibility are crucial for clinical application.

An optical aptasensor for real-time quantification of endotoxin: From ensemble to single-molecule resolution.

Endotoxin is a deadly pyrogen, rendering it crucial to monitor with high accuracy and efficiency. However, current endotoxin detection relies on multistep processes that are labor-intensive, time-consuming, and unsustainable. Here, we report an aptamer-based biosensor for the real-time optical detection of endotoxin. The endotoxin sensor exploits the distance-dependent scattering of gold nanoparticles (AuNPs) coupled to a gold nanofilm. This is enabled by the conformational changes of an endotoxin-specific aptamer upon target binding. The sensor can be used in an ensemble mode and single-particle mode under dark-field illumination. In the ensemble mode, the sensor is coupled with a microspectrometer and exhibits high specificity, reliability (i.e., linear concentration to signal profile in logarithmic scale), and reusability for repeated endotoxin measurements. Individual endotoxins can be detected by monitoring the color of single AuNPs via a color camera, achieving single-molecule resolution. This platform can potentially advance endotoxin detection to safeguard medical, food, and pharmaceutical products.

A transient, closed-loop network of wireless, body-integrated devices for autonomous electrotherapy.

Temporary postoperative cardiac pacing requires devices with percutaneous leads and external wired power and control systems. This hardware introduces risks for infection, limitations on patient mobility, and requirements for surgical extraction procedures. Bioresorbable pacemakers mitigate some of these disadvantages, but they demand pairing with external, wired systems and secondary mechanisms for control. We present a transient closed-loop system that combines a time-synchronized, wireless network of skin-integrated devices with an advanced bioresorbable pacemaker to control cardiac rhythms, track cardiopulmonary status, provide multihaptic feedback, and enable transient operation with minimal patient burden. The result provides a range of autonomous, rate-adaptive cardiac pacing capabilities, as demonstrated in rat, canine, and human heart studies. This work establishes an engineering framework for closed-loop temporary electrotherapy using wirelessly linked, body-integrated bioelectronic devices.

Single molecule detection of nitric oxide enabled by d(AT)15 DNA adsorbed to near infrared fluorescent single-walled carbon nanotubes.

We report the selective detection of single nitric oxide (NO) molecules using a specific DNA sequence of d(AT)(15) oligonucleotides, adsorbed to an array of near-infrared fluorescent semiconducting single-walled carbon nanotubes (AT(15)-SWNT). While SWNT suspended with eight other variant DNA sequences show fluorescence quenching or enhancement from analytes such as dopamine, NADH, L-ascorbic acid, and riboflavin, d(AT)(15) imparts SWNT with a distinct selectivity toward NO. In contrast, the electrostatically neutral polyvinyl alcohol enables no response to nitric oxide, but exhibits fluorescent enhancement to other molecules in the tested library. For AT(15)-SWNT, a stepwise fluorescence decrease is observed when the nanotubes are exposed to NO, reporting the dynamics of single-molecule NO adsorption via SWNT exciton quenching. We describe these quenching traces using a birth-and-death Markov model, and the maximum likelihood estimator of adsorption and desorption rates of NO is derived. Applying the method to simulated traces indicates that the resulting error in the estimated rate constants is less than 5% under our experimental conditions, allowing for calibration using a series of NO concentrations. As expected, the adsorption rate is found to be linearly proportional to NO concentration, and the intrinsic single-site NO adsorption rate constant is 0.001 s(-1) µM NO(-1). The ability to detect nitric oxide quantitatively at the single-molecule level may find applications in new cellular assays for the study of nitric oxide carcinogenesis and chemical signaling, as well as medical diagnostics for inflammation.

Wireless skin sensors for physiological monitoring of infants in low-income and middle-income countries.

Globally, neonatal mortality remains unacceptability high. Physiological monitoring is foundational to the care of these vulnerable patients to assess neonatal cardiopulmonary status, guide medical intervention, and determine readiness for safe discharge. However, most existing physiological monitoring systems require multiple electrodes and sensors, which are linked to wires tethered to wall-mounted display units, to adhere to the skin. For neonates, these systems can cause skin injury, prevent kangaroo mother care, and complicate basic clinical care. Novel, wireless, and biointegrated sensors provide opportunities to enhance monitoring capabilities, reduce iatrogenic injuries, and promote family-centric care. Early validation data have shown performance equivalent to (and sometimes exceeding) standard-of-care monitoring systems in premature neonates cared for in high-income countries. The reusable nature of these sensors and compatibility with low-cost mobile phones have the future potential to enable substantially lower monitoring costs compared with existing systems. Deployment at scale, in low-income countries, holds the promise of substantial improvements in neonatal outcomes.

Delivery of local anaesthetics by a self-assembled supramolecular system mimicking their interactions with a sodium channel.

Site-1 sodium channel blockers (S1SCBs) act as potent local anaesthetics, but they can cause severe systemic toxicity. Delivery systems can be used to reduce the toxicity, but the hydrophilicity of S1SCBs makes their encapsulation challenging. Here, we report a self-assembling delivery system for S1SCBs whose design is inspired by the specific interactions of S1SCBs with two peptide sequences on the sodium channel. Specifically, the peptides were modified with hydrophobic domains so that they could assemble into nanofibres that facilitated specific binding with the S1SCBs tetrodotoxin, saxitoxin and dicarbamoyl saxitoxin. Injection of S1SCB-carrying nanofibres at the sciatic nerves of rats led to prolonged nerve blockade and to reduced systemic toxicity, with benign local-tissue reaction. The strategy of mimicking a molecular binding site via supramolecular interactions may be applicable more broadly to the design of drug delivery systems for receptor-mediated drugs.

Super Tough and Spontaneous Water-Assisted Autonomous Self-Healing Elastomer for Underwater Wearable Electronics.

Self-healing soft electronic material composition is crucial to sustain the device long-term durability. The fabrication of self-healing soft electronics exposed to high moisture environment is a significant challenge that has yet to be fully achieved. This paper presents the novel concept of a water-assisted room-temperature autonomous self-healing mechanism based on synergistically dynamic covalent Schiff-based imine bonds with hydrogen bonds. The supramolecular water-assisted self-healing polymer (WASHP) films possess rapid self-healing kinetic behavior and high stretchability due to a reversible dissociation-association process. In comparison with the pristine room-temperature self-healing polymer, the WASHP demonstrates favorable mechanical performance at room temperature and a short self-healing time of 1 h; furthermore, it achieves a tensile strain of 9050%, self-healing efficiency of 95%, and toughness of 144.2 MJ m-3 . As a proof of concept, a versatile WASHP-based light-emitting touch-responsive device (WASHP-LETD) and perovskite quantum dot (PeQD)-based white LED backlight are designed. The WASHP-LETD has favorable mechanical deformation performance under pressure, bending, and strain, whereas the WASHP-PeQDs exhibit outstanding long-term stability even over a period exceeding one year in a boiling water environment. This paper provides a mechanically robust approach for producing eco-friendly, economical, and waterproof e-skin device components.

Wireless, implantable catheter-type oximeter designed for cardiac oxygen saturation.

Accurate, real-time monitoring of intravascular oxygen levels is important in tracking the cardiopulmonary health of patients after cardiothoracic surgery. Existing technologies use intravascular placement of glass fiber-optic catheters that pose risks of blood vessel damage, thrombosis, and infection. In addition, physical tethers to power supply systems and data acquisition hardware limit freedom of movement and add clutter to the intensive care unit. This report introduces a wireless, miniaturized, implantable optoelectronic catheter system incorporating optical components on the probe, encapsulated by soft biocompatible materials, as alternative technology that avoids these disadvantages. The absence of physical tethers and the flexible, biocompatible construction of the probe represent key defining features, resulting in a high-performance, patient-friendly implantable oximeter that can monitor localized tissue oxygenation, heart rate, and respiratory activity with wireless, real-time, continuous operation. In vitro and in vivo testing shows that this platform offers measurement accuracy and precision equivalent to those of existing clinical standards.

Bioresorbable Multilayer Photonic Cavities as Temporary Implants for Tether-Free Measurements of Regional Tissue Temperatures.

Objective and Impact Statement. Real-time monitoring of the temperatures of regional tissue microenvironments can serve as the diagnostic basis for treating various health conditions and diseases. Introduction. Traditional thermal sensors allow measurements at surfaces or at near-surface regions of the skin or of certain body cavities. Evaluations at depth require implanted devices connected to external readout electronics via physical interfaces that lead to risks for infection and movement constraints for the patient. Also, surgical extraction procedures after a period of need can introduce additional risks and costs. Methods. Here, we report a wireless, bioresorbable class of temperature sensor that exploits multilayer photonic cavities, for continuous optical measurements of regional, deep-tissue microenvironments over a timeframe of interest followed by complete clearance via natural body processes. Results. The designs decouple the influence of detection angle from temperature on the reflection spectra, to enable high accuracy in sensing, as supported by in vitro experiments and optical simulations. Studies with devices implanted into subcutaneous tissues of both awake, freely moving and asleep animal models illustrate the applicability of this technology for in vivo measurements. Conclusion. The results demonstrate the use of bioresorbable materials in advanced photonic structures with unique capabilities in tracking of thermal signatures of tissue microenvironments, with potential relevance to human healthcare.

Skin-interfaced biosensors for advanced wireless physiological monitoring in neonatal and pediatric intensive-care units.

Standard clinical care in neonatal and pediatric intensive-care units (NICUs and PICUs, respectively) involves continuous monitoring of vital signs with hard-wired devices that adhere to the skin and, in certain instances, can involve catheter-based pressure sensors inserted into the arteries. These systems entail risks of causing iatrogenic skin injuries, complicating clinical care and impeding skin-to-skin contact between parent and child. Here we present a wireless, non-invasive technology that not only offers measurement equivalency to existing clinical standards for heart rate, respiration rate, temperature and blood oxygenation, but also provides a range of important additional features, as supported by data from pilot clinical studies in both the NICU and PICU. These new modalities include tracking movements and body orientation, quantifying the physiological benefits of skin-to-skin care, capturing acoustic signatures of cardiac activity, recording vocal biomarkers associated with tonality and temporal characteristics of crying and monitoring a reliable surrogate for systolic blood pressure. These platforms have the potential to substantially enhance the quality of neonatal and pediatric critical care.