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The need for novel, minimally invasive diagnostic, prognostic, and therapeutic biomedical devices has garnered increased interest in recent years. Microneedle (MN) technology has stood out as a promising new method for drug delivery, as well as extraction of interstitial fluid (ISF). ISF comprises a large portion of the extracellular fluid in living organisms yet remains inadequately characterized for clinical applications. Current MN research has focused on the fabrication of needles with different materials like silicone, carbon, and metals. However, little effort has been put forth into improving MN holders and patches that can be used with low cost MNs, which could effectively change how MNs are attached to the human body. Here, we describe different 3D-printed MN holders, printed using an MJP Pro 2500 3D printer, and compare the ISF extraction efficiencies in CD Hairless rats. We varied design parameters that may affect the skin-holder interface, such as throat thickness, tip curvature, and throat diameter. MN arrays, with insertion depths of 1500 μm, had extraction efficiencies of 0.44 ± 0.35, 0.85 ± 0.64, 0.32 ± 0.21, or 0.44 ± 0.46 µl/min when designed with flat, concave, convex, or bevel profile geometries, respectively. Our results suggest ISF extraction is influenced by MN holder design parameters and that a concave tip design is optimal for extracting ISF from animals. The future direction of this research aims to enable a paradigm in MN design that maximizes its efficiency and engineering performance in terms of volume, pressure, and wearability, thereby automatizing usage and reducing patient intervention to ultimately benefit remote telemedicine.

The need for hollow microneedle arrays is important for both drug delivery and wearable sensor applications; however, their fabrication poses many challenges. Hollow metal microneedle arrays residing on a flexible metal foil substrate were created by combining additive manufacturing, micromolding, and electroplating approaches in a process we refer to as electromolding. A solid microneedle with inward facing ledge was fabricated with a two photon polymerization (2PP) system utilizing laser direct write (LDW) and then molded with polydimethylsiloxane. These molds were then coated with a seed layer of Ti/Au and subsequently electroplated with pulsed deposition to create hollow microneedles. An inward facing ledge provided a physical blocking platform to restrict deposition of the metal seed layer for creation of the microneedle bore. Various ledge sizes were tested and showed that the resulting seed layer void could be controlled via the ledge length. Mechanical properties of the PDMS mold was adjusted via the precursor ratio to create a more ductile mold that eliminated tip damage to the microneedles upon removal from the molds. Master structures were capable of being molded numerous times and molds were able to be reused. SEM/EDX analysis showed that trace amounts of the PDMS mold were transferred to the metal microneedle upon removal. The microneedle substrate showed a degree of flexibility that withstood over 100 cycles of bending from side to side without damaging. Microneedles were tested for their fracture strength and were capable of puncturing porcine skin and injecting a dye.

Origami-inspired DNA aptamer arrays prevent blood clotting in hemodialysis circuits.

Coadministration of antibody-drug conjugates with the parent antibody improves delivery to solid tumor beds.

Combining ultrasound release and molecular targeting selectively delivered extremely toxic and hydrophobic drugs to tumor cells.

Three-dimensional titanium surfaces patterned with nanometer-sized features demonstrate accelerated bone growth and mineralization in mice.

Molecular design principles increase accumulation of an antibiotic in multidrug resistant Gram-negative bacteria.

A near-infrared light-responsive nanoreactor enables heat ablation of tumors while preventing the inflammatory response to this approach.

Interstitial fluid (ISF) has recently garnered interest as a biological fluid that could be used as an alternate to blood for biomedical applications, diagnosis, and therapy. ISF extraction techniques are promising because they are less invasive and less painful than venipuncture. ISF is an alternative, incompletely characterized source of physiological data. Here, we describe a novel method of ISF extraction in rats, using microneedle arrays, which provides volumes of ISF that are sufficient for downstream analysis techniques such as proteomics, genomics, and extracellular vesicle purification and analysis. This method is potentially less invasive than previously reported techniques. The limited invasiveness and larger volumes of extracted ISF afforded by this microneedle-assisted ISF extraction method provide a technique that is less stressful and more humane to laboratory animals, while also allowing for a reduction in the numbers of animals needed to acquire sufficient volumes of ISF for biomedical analysis and application.

We review some emerging trends in transduction, connectivity and data analytics for Point-of-Care Testing (POCT) of infectious and non-communicable diseases. The patient need for POCT is described along with developments in portable diagnostics, specifically in respect of Lab-on-chip and microfluidic systems. We describe some novel electrochemical and photonic systems and the use of mobile phones in terms of hardware components and device connectivity for POCT. Developments in data analytics that are applicable for POCT are described with an overview of data structures and recent AI/Machine learning trends. The most important methodologies of machine learning, including deep learning methods, are summarised. The potential value of trends within POCT systems for clinical diagnostics within Lower Middle Income Countries (LMICs) and the Least Developed Countries (LDCs) are highlighted.

IMPACT: We present a minimally-invasive approach to monitoring heavy metal exposures in geographically disperse populations; this framework may encourage and facilitate greater participation in a broad range of related clinical studies that require biosampling. OBJECTIVES/GOALS: We hypothesize that microneedle array (MA) extraction of interstitial fluid (ISF) will enable minimally-invasive quantitation of heavy metal (HM) exposure. We establish analytical parameters for ICP-MS analysis of HMs in ISF, quantify baseline HM content in ISF vs other fluids, and characterize a mixed HM exposure model. METHODS/STUDY POPULATION: Recent advances in ISF extraction and analysis suggest a minimally-invasive to monitor HM exposure longitudinally in both urban and dispersed communities. ISF can be collected with MAs and is a rich source of disease and exposure biomarkers. To refine analytical methods, Human subjects with no underlying skin disease were recruited into the IRB-approved study. Each subject had blood and urine collected. ISF was also collected using 3D-printed MA-holders. The fluids were analyzed, using ICP-MS, to quantify the levels of uranium (U), cadmium (Cd), vanadium (V), and arsenic (As). Additionally, we analyzed 2,770 subjects from the public NHANES dataset from 2018-2019. Python and Scikit-learn were used to analyze the demographics, survey responses, and metal concentrations for these individuals. RESULTS/ANTICIPATED RESULTS: While several studies have described the surface water and sediment content of toxic metals, determining biological loads remains challenging due to the need to collect blood or urine from a dispersed rural population over time. Our preliminary results suggest similar HM concentrations in ISF, compared with blood in a small unexposed population. Analysis of subjects from the NHANES public datasets suggest similar baseline blood HM concentrations in diverse subject populations with some differences in Cd depending on smoking and e-cigarette usage. Correlation maps also suggest possible synergy between different metals with cobalt and chromium showing the highest correlation. The initial results from this study have been applied to develop a mixed HM exposure model in rats for further translational testing. DISCUSSION/SIGNIFICANCE OF FINDINGS: We present a minimally-invasive HM monitoring approach. Exposure to multiple HMs is suspected to have additive or synergistic harmful health effects. We ultimately envision a wearable microneedle patch that could be mailed to individuals or distributed through community centers, worn for a few hours, and returned to a central laboratory.

Dermal interstitial fluid (ISF) is an underutilized information-rich biofluid potentially useful in health status monitoring applications whose contents remain challenging to characterize. Here, we present a facile microneedle approach for dermal ISF extraction with minimal pain and no blistering for human subjects and rats. Extracted ISF volumes were sufficient for determining transcriptome, and proteome signatures. We noted similar profiles in ISF, serum, and plasma samples, suggesting that ISF can be a proxy for direct blood sampling. Dynamic changes in RNA-seq were recorded in ISF from induced hypoxia conditions. Finally, we report the first isolation and characterization, to our knowledge, of exosomes from dermal ISF. The ISF exosome concentration is 12–13 times more enriched when compared to plasma and serum and represents a previously unexplored biofluid for exosome isolation. This minimally invasive extraction approach can enable mechanistic studies of ISF and demonstrates the potential of ISF for real-time health monitoring applications., Philip Miller et al. present an approach for extracting dermal interstitial fluid (ISF) using an array of hollow microneedles in a cylindrical substrate that minimizes skin compression and tissue damage. They extract larger volumes of ISF suitable for downstream analyses, compared to previous reports.

Electroplated iron was investigated as a novel material for microneedle fabrication due to its recent success as a biocompatible metal in other medical device applications. Hollow polymer microneedles were made using a laser direct write process that involved two-photon polymerization of a commercially available Class 2a biocompatible polymer and subsequent electroplating of this structure with iron. Electroplating bath and deposition conditions were shown to affect the mechanical properties of both iron plated microneedles and iron plated on planar polymer substrates. Conditions for depositing the iron coatings were investigated in terms of grain size, residual strain, and elemental composition for planar iron samples. Fracture strength and puncture mechanics into ex vivo porcine skin for iron coated hollow microneedles were examined. Biocompatibility testing was performed using the MTT assay against human epidermal keratinocytes with several concentrations of iron extract to investigate iron as a material used for transdermal applications. Iron coatings proved to significantly improve the strength of the hollow polymer microneedles and sustained structural integrity up to 7 insertions into porcine skin without bending. A commercially available device (Medtronic MiniMed Quick-Serter®) was used for controlled application of microneedles into porcine skin and estimations of insertion forces for the device were made. Plating conditions were optimized such that an adherent, uniform, and high purity iron coating was deposited onto polymer substrates and polymer microneedles without delamination or fracturing of the microneedles upon ex vivo insertion into porcine skin.

Surface acoustic wave (SAW) sensors can rapidly detect Ebola antigens at the point-of-care without the need for added reagents, sample processing, or specialized personnel. This preliminary study demonstrates SAW biosensor detection of the Ebola virus in a concentration-dependent manner. The detection limit with this methodology is below the average level of viremia detected on the first day of symptoms by PCR. We observe a log-linear sensor response for highly fragmented Ebola viral particles, with a detection limit corresponding to 1.9 × 104 PFU/mL prior to virus inactivation. We predict greatly improved sensitivity for intact, infectious Ebola virus. This point-of-care methodology has the potential to detect Ebola viremia prior to symptom onset, greatly enabling infection control and rapid treatment. This biosensor platform is powered by disposable AA batteries and can be rapidly adapted to detect other emerging diseases in austere conditions.

Few residency curricular interventions have focused on improving well-being and promoting humanism. We describe the implementation of a novel curriculum based on small-group reflection rounds—the Emergency Medicine Reflection Rounds (EMRR)—at a 4-year US emergency medicine (EM) residency. During the inaugural year (2010–2011), nine residents volunteered to take part in 1-hour monthly sessions with faculty facilitators. Residents were provided with a confidential environment to discuss difficult ethical and interpersonal encounters from their clinical experiences. Ongoing feedback from participants was solicited, culminating with a four-question survey in which all respondents remarked that the EMRR contributed to improving their own well-being and agreed that it provided an important forum for residents to discuss difficult issues in a safe environment. In this article, we describe our innovation as an example of a wellness initiative that has promoted reflective practice and fostered cooperative learning around the communication, professional, and ethical challenges inherent in EM practice. Our EMRR model may be useful to other EM residences looking to supplement their wellness curriculum.

One approach to the noninvasive monitoring of blood glucose concentration is to monitor glucose concentrations in tear fluid. While several methods for sensing glucose in tear fluid have been proposed, controversy remains as to the precise concentrations of tear glucose in normal and diabetic subjects and as to whether tear fluid glucose concentrations correlate with blood glucose concentrations. This review covers the present understanding of the physiology of glucose transport in tears, the regulation of the aqueous tear fraction, and studies of tear glucose concentration over the last 80 years. The various tear collection methods employed greatly influence the measured tear glucose concentrations. Studies that involve mechanical irritation of the conjunctiva during sampling measure the highest tear glucose concentrations, while studies that avoid tear stimulation measure the lowest concentrations. Attempts to monitor tear glucose concentration in situ by using contact lens-based sensing devices are discussed, and new observations are presented of tear glucose concentration obtained by a method designed to avoid tear stimulation. These studies indicate the importance of the sampling method in determining tear glucose concentrations. On the basis of these results, we discuss the future of in vivo tear glucose sensing and outline the studies needed to resolve the remaining questions about the relationship between tear and blood glucose concentrations.

We have developed a mass spectrometry-based method that allows one to accurately determine the glucose concentration of tear fluid. We used a 1 microL micro-capillary to collect tear fluid from the tear meniscus with minimal irritation of the eye. We analyzed the 1 muL volume of collected tear fluid with liquid-chromatography electrospray ionization mass spectrometry with the use of D-glucose-6,6-d2 as an internal standard. Repeated measurements and a recovery experiment on pooled, onion-induced tears showed that the analysis of the glucose in tears was precise (4% relative standard deviation) and provided 100% recovery. We found the tear glucose concentration of one fasting nondiabetic subject to be 13 to 51 microM while the onion-induced tear glucose concentration of a different nondiabetic subject to be 211 to 256 microM.

Background: There is considerable disagreement regarding the concentration of glucose in tears and its relationship to the concentration in blood. Improved sampling and analysis methods may resolve these discrepancies and possibly provide a basis for in situ tear glucose sensors. Methods: We used liquid chromatography (LC) with electrospray ionization mass spectrometry (ESI-MS) to determine glucose in 1-μL tear fluid samples obtained from 25 fasting study participants. Tear fluid was collected with microcapillaries and a slitlamp microscope. Results: The median (range) of fasting tear glucose concentrations was 28 (7–161) μmol/L or 0.50 (0.13–2.90) mg/dL. The SD of tear glucose measurements for individuals varied linearly with the mean tear glucose concentration and was approximately half of the mean. We found no significant difference in tear glucose concentrations between contact lens users and nonusers (P = 0.715). We observed significant correlations between fasting blood and tear glucose concentrations (R = 0.50, P = 0.01). Conclusions: Our tear fluid collection and analysis method enables reliable measurement of equilibrium, fasting tear glucose concentrations. These concentrations are lower than those previously reported for nondiabetic persons. Larger population studies are required to determine correlations between blood and tear glucose concentrations and to determine the utility of contact lens–based sensors for the monitoring of diabetes. Our methods are applicable for study of other tear fluid analytes and may prove useful for monitoring other disease states.

Diabetic foot infections have a 15-25% lifetime incidence in diabetics, and account for more than half of all non-traumatic lower extremity amputations. Currently, the most accurate means of non-invasively diagnosing osteomyelitis in patients with foot infections is with gadolinium-enhanced MRI. However, gadolinium has limited specificity, as it not only enhances infection but also neuropathic changes and other forms of sterile inflammation. Also, safety concerns about gadolinium have recently been raised given the recent discovery that gadolinium (a molecule that some animal studies suggest is a neurotoxin) deposits in the brains in some patients with normal renal function. Making the correct diagnosis of osteomyelitis is paramount, as an MRI that is falsely positive for osteomyelitis may lead to unnecessary bone biopsies, prolonged antibiotic courses, or even amputation. Ferumoxytol is a superparamagnetic iron oxide nanoparticle (SPION) that is FDA approved for iron replacement in patients with chronic kidney disease. Ferumoxytol is also widely studied as a contrast agent for MRI imaging. Ferumoxytol is taken up by macrophages, and thus provides contrast in areas of active infection, manifested as negative enhancement (eg hypo-enhancement) on T2/T2* sequences. In this prospective feasibility study, ferumoxytol was used as an MRI contrast agent in patients with osteomyelitis. We included non-septic patients with suspected osteomyelitis who had a baseline MRI using standard sequences. Patients without a contra-indication to gadolinium also were imaged with standard T1 sequences after gadolinium administration. Ferumoxytol was then administered, and ferumoxytol contrasted images were then obtained 12-24 hours after ferumoxytol infusion. When available, resected tissue was analyzed for iron content and macrophages by immunohistochemistry. To date we have enrolled 8 patients with possible osteomyelitis. Because this was a feasibility study, statistical analysis is not meaningful in this small cohort of patients. Two patients had strong contrast-enhanced evidence of osteomyelitis on both gadolinium and ferumoxytol imaging. Osteomyelitis was confirmed by histology of the amputated digits for both patients. Representative images from a patient with biopsy confirmed osteomyelitis is shown in Figure 1. Another patient had images that did not demonstrate hypo-enhancement on ferumoxytol imaging, but did have evidence of osteomyelitis on gadolinium-enhanced imaging. This patient underwent an amputation after antibiotics failed to heal this patient's wound, and the pathology came back negative for osteomyelitis. Five other patients did not have tissue available as a reference standard with which to analyze the accuracy of the ferumoxytol enhanced images. In conclusion, macrophage imaging using ferumoxytol-contrasted MRI merits further study for use in the diagnosis of osteomyelitis. Figure 1. Patient with 1st distal phalanx osteomyelitis. STIR T2 weighted image precontrast (A), STIR T2 weighted image approximately 16 hours post-ferumoxytol (B), and Heme weighted T2* image (C.) about 16 hours post ferumoxytol showing hypo-enhancement in areas of macrophage iron uptake in distal 1st phalanx in the post-ferumoxytol scans. Figure 1. Patient with 1st distal phalanx osteomyelitis. STIR T2 weighted image precontrast (A), STIR T2 weighted image approximately 16 hours post-ferumoxytol (B), and Heme weighted T2* image (C.) about 16 hours post ferumoxytol showing hypo-enhancement in areas of macrophage iron uptake in distal 1st phalanx in the post-ferumoxytol scans. Disclosures Off Label Use: ferraheme is for iron replacement, and we are using it as a contrast agent..

Coronary Heart Disease is the leading cause of death in the United States and was responsible for approximately one of every five deaths in 2003 [1]. Unnecessary admissions to US Hospitals of patients with suspected Acute Coronary Syndrome (ACS) is estimated to cost about 12 billion dollars a year [2]. The earliest biochemical markers currently assayed do not appear in the blood for hours after the onset of chest pain; a rapid test for myocardial ischemia would help to expedite treatment and avoid unnecessary hospital admissions [3].Copyright © 2007 by ASME

The difficulty of rapid, definitive diagnosis of myocardial ischemia leads to unnecessary hospital admissions and treatment delays. Previously, decreased metal binding affinity in human serum was investigated as a marker for myocardial ischemia. Polymerized Crystalline Colloidal Array (PCCA) sensors for Ni2+ may be useful in developing a point-of-care test to determine metal binding affinity in plasma and to help rule out myocardial ischemia. PCCA sensors for Ni2+, with 5-amino-8-hydroxyquinoline as a chelating agent, were tested in aqueous solutions and diluted human plasma. The peak wavelength diffracted by the sensors was monitored by reflectance spectrometry and correlated with Ni2+ concentration. The PCCA sensors show a linear response to aqueous Ni2+ concentrations between 0.2 and 1.0 mmol L(-1), and can detect changes in free Ni2+ concentration of60 micromol L(-1). The sensors respond at physiologic pH and can be reversibly dehydrated. The PCCA sensors developed here can report on free Ni2+ concentration in the presence of human plasma. These sensors can be used to detect a decrease in the Ni2+ affinity of plasma proteins, which may indicate recent myocardial ischemia. PCCA sensors offer a practical approach to rapid, point-of-care detection of a proposed biochemical signature of myocardial ischemia.