Minimal Volume Research Articles

Real-time, specific, and label-free transistor-based sensing of organophosphates in liquid

Organophosphates (OP), commonly used in agriculture and as chemical warfare agents, pose significant environmental risks, necessitating real-time, low-cost OP detection methods. In particular, liquid-phase OP sensing with minimal sample volumes is crucial. While several methods allow rapid detection of low concentrations of OP vapors, they are effective only in the short term, while vapors are still being produced. Many OP compounds are semi-volatile, leading to the contamination of water, soil, and surfaces, posing a risk of secondary, long-term exposure. Detecting this contamination requires methods that can be directly applied to droplets of the affected medium. Currently, no method provides the desired combination of ultra-sensitivity, quantitative detection, rapid response, and low-cost for detecting OPs in liquid samples. This study aims to demonstrate quantitative, low-cost, real-time, specific, and label-free OP sensing in ultra-small samples using a transistor-based approach. The current work employs the 2-(4-Aminophenyl)-1,1,1,3,3,3-hexafluoro-2-propanol (aminophenyl-HFIP) functionalized meta-nano-channel field-effect chemical sensor (MNChem sensor) to monitor the organophosphate, diethyl cyanophosphonate (DCNP), in liquid samples. The silicon component of the MNChem is fabricated using a complementary metal-oxide semiconductor (CMOS) process, and the amine-based chemical functionalization of the sensing area is performed post-fabrication. The MNChem sensor provides electrostatic control over the source-drain current (IDS), allowing an optimized channel configuration that efficiently transduces localized OP recognition events into significant IDS variations. Sensing is performed using 0.5 μL buffer solution to simulate a miniature field-deployable sensor for on-site liquid analysis. We report the sensing of DCNP with a limit-of-detection of 100 fg/mL, a dynamic range of 9 orders of magnitude, and excellent linearity (≥0.97) and sensitivity. Control measurements confirm the specificity and reliability of the sensor's response, validating its applicability. This study introduces a novel method for OP detection in contaminated droplets using a low-cost disposable transistor technology.

A-354 Evaluating Emergent POC Technology for Sickle Cell Testing in Resource Limited Settings

Abstract Background Sickle cell disease (SCD) represents a collection of inherited hematological disorders characterized by abnormal sickle-shaped erythrocytes resulting in an increased risk of morbidity and mortality. SCD represents a significant global health burden, affecting more than 300,000 newborns per year. Most of these births occur in resource limited areas, including sub-Saharan Africa, where the mortality rate before the age of five is estimated to be as high as 50-80% and the existing infrastructure and resources cannot support most current and robust methods that offer hemoglobin variant detection and quantification for the diagnosis and monitoring of SCD. While newborn screening programs (NBS) to identify individuals affected with SCD have demonstrated efficacy in reducing morbidity and early mortality, NBS programs are limited outside of the US and Europe and face many practical challenges for universal implementation in a resource limited setting. The need for inexpensive and reliable hemoglobin variant detection and quantification at the Point of Care is essential to the diagnosis and management of SCD in resource limited settings with a high prevalence of SCD, and the expansion of NBS programs. This study aims to evaluate an inexpensive testing strategy using two methodologies for POC screening and confirmation of SCD that could be supported in a low resource setting. Methods The two-step testing strategy for evaluation of POC testing for hemoglobin variant detection and quantification included testing residual specimens from normal and known sickle cell patients by first screening with the HemoTypeSC, a qualitative lateral flow immunoassay (LFIA) that has improved sensitivity and specificity from other available LFIA methodologies given the use of monoclonal antibodies for the detection of hemoglobin variants. Confirmatory testing and quantification of hemoglobin variants was accomplished with the use of the Gazelle POC test a miniaturized chip-based cellulose acetate electrophoresis device capable of identification and quantification of normal and variant hemoglobin. Statistical evaluation of device performance and clinical agreement between the device and known disease status was achieved in EP evaluator. Results The two-tier testing strategy demonstrated effective and inexpensive mechanism for SCD screening and confirmation. Overall, the HemoTypeSC and Gazelle demonstrated 100% qualitative agreement between methods, with the total cost of the two-tiered testing strategy estimated at under $6 per sample. Conclusions In conclusion, the two-tiered approach using the HemoTypeSC and Gazelle yielded a practical and cost-effective strategy for screening and confirmation of hemoglobin variants for the detection and monitoring of SCD. Both the strip and chip-based methodologies provide rapid results, are accessible at the point-of-care, and require minimal sample volume, a feature ideal for use in a pediatric population in low resource settings. Overall, these methods show promise for the use and expansion of NBS programs to improve public health initiatives for the diagnosis of SCD.

Exploring ammonia adsorption and filtration efficiency of ceramic membranes derived from weathered basalt: Fabrication analysis and application in wastewater treatment

This study aims to develop an innovative ceramic membrane derived from naturally-occurring weathered basalt (NWB) for the effective adsorption and filtration of ammonium ions (NH+4) from wastewater. The NWB was subjected to calcination to produce CWB-750 and further combined with activated carbon to form CWB-AC-950. Comprehensive characterization using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FT-IR), and Brunauer-Emmett-Teller (BET) analysis revealed that CWB-AC-950 possessed a significantly high surface area of 121.7 m²/g and a minimal pore volume of 6.2 nm, indicating its enhanced adsorption capabilities. In practical filtration tests, CWB-AC-950 demonstrated a remarkable reduction in NH+4 concentration, decreasing it from an initial 30 mg/L to 15.25 mg/L. This substantial decrease underscores the membrane's efficiency in adsorbing and removing ammonium ions from contaminated water. Furthermore, the integration of activated carbon with calcined basalt not only improved the adsorption performance but also maintained the structural integrity and reusability of the membrane. These findings illustrate the potential of CWB-AC-950 as a promising and cost-effective medium for adsorption and filtration in wastewater treatment applications.The development of CWB-AC-950 contributes significantly to environmental remediation efforts by offering an efficient and low-cost alternative to conventional filtration materials. Its ability to maintain performance across multiple cycles underscores its potential for practical applications in large-scale wastewater treatment facilities, thus providing a sustainable solution to address the growing global water pollution crisis.

UPLC-MS/MS analysis of axitinib and pharmacokinetic application in beagle dogs

ObjectiveTo develop a method for determining the concentration of axitinib in beagle dog plasma and utilize this method to investigate the pharmacokinetics of orally administered axitinib in beagle dogs. MethodsPlasma samples were processed using acetonitrile precipitation and analyzed by UPLC-MS/MS with sunitinib as an internal standard (IS). Chromatographic separation was achieved on a Waters Acquisition UPLC BEH C18 column (50 mm × 2.1 mm, 1.7 μm) with a gradient elution of acetonitrile and 0.1 % formic acid. Mass spectrometry uses an electrospray ion source for positive ion detection in a multiple reaction monitoring mode. The monitored ion transitions for axitinib and sunitinib were m/z 387 → 355.96 and m/z 399.3 → 282.96, respectively. Six beagle dogs were administered 0.33 mg/kg of axitinib orally, and venous blood samples were collected at 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, and 24 h post-dose for pharmacokinetic analysis. ResultsThe assay demonstrated a linear range of 0.5–100 ng/mL (r2 = 0.9992), and the lower limit of quantification was up to 0.5 ng/mL. Precision, as assessed by relative standard deviation (RSD), was within 8.64 % for both intraday and interday variability. The relative error (RE) for precision from −2.77 %–1.20 %. The recovery rate of the analytes exceeded 85.28 % and the matrix effect was approximately 100 %. Plasma samples maintained stability under various conditions, including room temperature storage for 12 h, processed on an automatic sampler at 4 °C for 6 h, three freeze-thaw cycles, and long-term storage at −80 °C for 60 days. Pharmacokinetic parameters were determined using DAS 2.0 software, revealing a half-life (T1/2) of 6.05 h and an area under the curve (AUC (0 →∞)) of 97.13 ng h/mL for axitinib. ConclusionsThe UPLC-MS/MS method developed in this study offers high specificity, rapid analysis, high recovery, excellent linearity, and minimal plasma volume requirements, making it well-suited for pharmacokinetic and drug interaction studies in beagles dogs.

Synthesis, Characterization and Electrochemical Performance of Bi2S3/Rice Husk-Based Activated Carbon Composites As Lithium Ion Battery Anodes

This study investigates the impact of hydrothermal duration on bismuth sulfide/activated carbon composites (Bi2S3/AC) by varying the duration to 8, 24, and 48 hours. The primary aim is to delineate the composite characteristics and electrochemical performance of Bi2S3/AC composites, aiming to produce anodes for lithium-ion batteries with high capacity, excellent cyclic stability, and minimal volume expansion. Activated carbon derived from rice husks was synthesized via a carbonization process and chemical activation using H3PO4 as an activator. Subsequently, the synthesis of Bi2S3/AC composites used bismuth nitrate pentahydrate and thiourea precursors through the hydrothermal method that involved three variations of hydrothermal duration: 8, 24, and 48 hours, denoted as BC8, BC24, and BC48, respectively. The FTIR test indicates the presence of Bi-S, C=C, and C-O groups in the three composite products, signifying the existence of bismuth sulfide and activated carbon. The XRD result reveals orthorhombic crystal forms in the composites, while the SEM-EDX mapping illustrates particle morphologies resembling flower-like shapes. These compositions comprise Bi 74.16%, S 11.37%, and C 10.43%. The GSA test suggests a mesoporous pore size in these composites. In final result, BC24 exhibits the highest electrical and ionic conductivity, measuring 2.12 × 10−3 S.cm−1 and 2.057 × 10−4 S.cm−1, respectively. The CV data of the BC24 composite indicates two reduction and oxidation peaks in the first cycle. Charge-discharge test on the BC24 composite exhibits a specific charge capacity of 445.51 mAh/g and a discharge capacity of 364.24 mAh/g.

Subtranscriptome analysis of phospholipases D in Loxosceles venom glands: Confirmation of predominance, intra-species diversity, and description of novel isoforms

Spiders of Loxosceles genus, or Brown spiders produce a potent venom with minimal volume and protein content. Among its toxins, phospholipases D (PLDs) are notable for causing primary local and systemic manifestations observed following envenomation. They degrade cellular phospholipids, mainly sphingomyelin and lysophosphatidylcholine. We present a robust and detailed analysis of PLD transcripts from venom glands of three major clinically relevant South American species—L. intermedia, L. laeta, and L. gaucho—using next-generation sequencing. Results confirmed that PLDs are the most highly expressed toxins, accounting for 65.4 % of expression in L. intermedia, 71.8 % in L. gaucho, and 50.4 % in L. laeta. These findings further support the idea that these enzymes form a protein family both within and across species. Eighteen contigs for PLDs were found for L. gaucho, 24 for L. intermedia, and 21 for L. laeta. A detailed analysis revealed that, although all contigs display conserved amino acid residues directly involved in catalysis, magnesium coordination, and substrate affinity, they also possess distinct primary sequences with important substitutions. Such data reinforces the hypothesis that these toxins may act synergistically. Furthermore, new PLD sequences were identified within the contigs. For L. intermedia, 14 potential new isoforms were identified; 16 for L gaucho; and 16 novel sequences for L. laeta. This indicates that there is still a wealth of undisclosed information about these toxins. These data will help identify structural and functional differences among these proteins, support future functional studies, and to the comprehensive understanding of the mechanism of action of PLDs.

Development and validation of a bioanalytical method using LC-MS/MS to quantify Zanamivir in human plasma.

This study presents the development and validation of a highly sensitive and accurate LC-MS/MS method for the quantification of Zanamivir in human plasma. Utilizing a mobile phase of MeOH and Ammonium Formate (30:70 v/v) and a protein precipitation extraction technique, the method achieves excellent specificity and reproducibility. The calibration curve demonstrated linearity from 4-80 ng/ml with a correlation coefficient (r²) ≥ 0.9994. The method adheres to FDA guidelines, exhibiting high precision and accuracy with intra-day and inter-day variations of 0.81-1.98%. The developed method, requiring a minimal sample volume and a short run time, ensures robustness and stability across various analytical conditions, making it an ideal tool for Zanamivir plasma concentration studies.

Single-pixel deep phase-shifting incoherent digital holography

Incoherent digital holography technology reduces the requirement for coherence of light sources, greatly expanding the application range of digital holography. In this paper, we designed a Multi-head attention single-pixel (MHASP) phase-shifting network for incoherent digital holography. The trained network has the capability to effortlessly predict three interferograms, encompassing phase shifts of 0, 2/3 π, and 4/3 π, solely from one-dimensional input data. Utilizing the conventional three-step phase-shifting method, we are able to effectively eliminate the DC and twin terms from the holographic reconstruction process, subsequently achieving a high-fidelity reconstruction facilitated by the employment of the back propagation algorithm. The comprehensive experimental findings clearly indicate that, beyond facilitating high-precision reconstruction, the introduced MHASP phase-shifting approach efficiently preserves 3D information through calibrating the back propagation distance, even when confronted with a reduced volume of holographic data. Furthermore, the introduced approach uses a network to replace the actual phase shift operation, which can better improve the utilization of object light energy. This approach not only circumvented the constraints posed by area array sensors but also facilitated high-fidelity imaging with minimal data volume, thereby expanding the horizons of incoherent digital holography applications in the realm of 3D imaging.

Regeneration of conventional and emerging PFAS-selective anion exchange resins used to treat PFAS-contaminated waters

Anion exchange resins (AERs) have emerged as a promising separation technology to remediate PFAS-contaminated waters due to their improved selectivities and capacities in comparison to legacy activated carbon adsorbents. Presently, site managers choose between AER systems employing resins defined as being ‘regenerable’ with relatively low PFAS selectivity, and PFAS-selective resins that are marketed as ‘single-use’ media intended for disposal upon PFAS breakthrough. However, the potential for these highly-selective adsorbents to be regenerated and/or reused remains poorly characterized. This study presents a comprehensive evaluation of the efficacy of various regenerant solution constituents, mixtures, and operational considerations on the regenerability of both ‘regenerable’ and ‘PFAS-selective’ AERs that were loaded during a pilot treatment study of PFAS-contaminated groundwater. Batch screening of regenerant solution constituents found that both classes of resins may be effectively regenerated using combinations of salt brine and organic cosolvent, with high cosolvent fractions being necessary for PFAS-selective AERs. While neither brine-only nor solvent-only regenerant solutions led to effective PFAS desorption, the efficacy of regeneration with brine/cosolvent mixtures varied with salt type and cosolvent composition. Chloride salts outperformed sulfate and bicarbonate salts, cosolvent efficacy depended on the volume fraction and type used, and highly non-polar solutions led to optimal PFAS desorption. Continuous-flow regeneration experiments showed near-complete PFAS desorption from regenerable AERs using 10 bed volumes (BVs) of 70 % methanolic brine solutions, whereas PFAS-selective resins required more bed volumes (30) of brines with higher methanol content (90 %) or a more hydrophobic cosolvent (n-propanol); increasing regenerant empty-bed contact time had minimal effect on PFAS desorption. > 90 % methanol recovery from the resulting waste regenerant mixtures was accomplished with negligible PFAS contamination using distillation, leaving a minimal volume of a PFAS-concentrated still bottoms waste that may be further treated for PFAS destruction. Life cycle analyses revealed that groundwater treatment using PFAS-selective AERs operated in a regenerable mode have lower environmental impacts and costs than systems using conventional regenerable AERs, and lower treatment costs than systems operated using PFAS-selective resins in a single-use mode. Although counterintuitive, these findings stem from the fact that higher cosolvent requirements for regeneration of PFAS-selective resins lead to greater internal recycling of regenerant solutions and much lower volumes of residual waste still bottoms that require off-site incineration or disposal.

Facile fabrication of the immuno-MALDI-MS chip for the enrichment of abused drug in human urine integrated with MALDI-MS analysis

BackgroundDrug abuse can result in both physical and mental health issues for individuals, and can also contribute to broader societal problems. The number of drug abuse cases rose to 296 million in 2021. The sample pretreatment methods commonly employed typically require longer processing times and occasionally necessitate derivatization. Furthermore, with the increase in sample sizes, traditional chromatography-mass spectrometry methods for analyzing abused drugs were no longer sufficient to handle such numerous samples. In this study, immuno-MALDI-MS chip were fabricated for specific enrichment of illicit drugs, integrating with the rapid and accurate capabilities of MALDI-MS for high-throughput analysis of drug abuse. ResultsThe immuno-MALDI-MS chip was successfully prepared by coating an aluminum chip with antibody-conjugated boronic acid-modified gold nanoparticles. Ketamine, a frequently abused illicit drug, served as the proof of concept for this study. The immuno-MALDI-MS chip was employed to selectively enrich ketamine in human urine samples, facilitating direct MALDI-MS analysis with the addition of α-CHCA matrix solution. The challenge of detecting abused drugs, exacerbated by interfering peaks in the low m/z region from salts and small molecules in human urine samples, was successfully overcome. The developed method exhibited a wide linear range of 10–5000 ng/mL with a limit of detection of 3.3 ng/mL for ketamine. Notably, the proposed method enabled high-throughput screening and accurate confirmation of ketamine concentrations in suspects' urine samples within few minutes, requiring a minimal sample volume of 1 μL. The obtained data were in complete agreement with the previous GC/MS analysis. SignificanceA straightforward, cost-effective and sensitive method for the selective enrichment and absolute quantification of abused drugs was developed using a homemade immuno-MALDI-MS chip integrated with MALDI-MS analysis. This method combines the advantages of immunoassay and mass spectrometry, offering both speed and accuracy. The reported method for the quantification of ketamine in human urine offers a practical approach and has the potential to analyze emerging new psychoactive substances in the future.

NanoRidge filters: Fabrication strategies and performance optimization for nano-scale microfluidic particle filtration.

Filters with high throughput, minimal dead volume, and greater sensitivity to particle size are needed, which traditional benchtop filtration cannot provide. Leveraging microfabrication techniques developed by the electronics and optics industries, the filters presented here feature a unique serpentine "NanoRidge" structure, offering a continuous filtration gap spanning over three meters on a compact 4 × 14.5 mm2 footprint. This design provides more precise size filtration cut-offs and consistent flow paths compared to traditional membrane filtration systems. Despite challenges associated with glass substrate deformation impacting uniform filter gap sizes, the study provides valuable insights into the development of NanoRidge filters (NRFs) for enhancing filtration efficiency in preparatory techniques and sample analysis. This study describes the fabrication and testing of these new filter types and directly compares the performance to traditional membrane filters using the metrics of particle size cut-off (the smallest difference in particle size which can be filtered vs passed) and particle loss. The NanoRidge filters were characterized using imaging (during fabrication, post-fabrication and use, fluorescent particles captured and small molecule dye), pressure and flow measurements, and a series of particle sizes "filter or pass" studies. Particle capacity (100-250 nm) ranged from 5 × 108 to 7 × 109 in 1 ml samples at a flow rate of 100 μl/min with backpressure in the range of 1-3 Bar. The optimized fabrication procedure for the 150 nm NRF yielded a small particle recovery of 95% while also achieving a large particle filtration of 73%. High filtration efficiency was also proven in the final 60 and 80 nm NRF fabrication procedures at 96% and 91%, respectively.

Traumatic brain injury: Advances in coagulopathy (Review).

Trauma is a prevalent cause of coagulopathy, with traumatic brain injury (TBI) accompanied by coagulation disorders particularly linked to adverse outcomes. TBI is distinguished by minimal bleeding volume and unique injury sites, which precipitate complex coagulation disturbances. Historically, research into trauma-induced coagulopathy has primarily concentrated on the molecular biology and pathophysiology of endogenous anticoagulation and inflammation. Nonetheless, recognizing that cells are the fundamental units of structure and function in all living organisms, the present review aimed to distill our understanding of coagulopathy post-TBI by elucidating the intricate cellular mechanisms involving endothelial cells, neutrophils and platelets. Additionally, this study evaluates the strengths and weaknesses of various diagnostic tools and discusses the characteristics of pharmacological treatments and potential therapies for patients with TBI and coagulation disorders. The aim of this review is to amalgamate recent updates in mechanistic research and innovative diagnostic and therapeutic methodologies, thereby fostering the progression of precision medicine within this specialized domain.

Maternal Breast Growth and Body Mass Index Are Associated with Low Milk Production in Women.

Maternal breast volume is determined by the quantity of glandular and adipose tissue, and it undergoes significant changes during pregnancy. These changes are intricately linked to the development of glandular tissue, which most likely reflects lactation capacity. Evidence indicates that women with overweight or obesity exhibit larger breast volume compared to those with a normal body mass index (BMI), emphasizing the close relationship between breast volume and maternal adiposity. Hence, we aim to investigate breast volume growth and maternal BMI as potential risk factors for low milk production. Lactating women (n = 609) from the Perth metropolitan area in Western Australia between 2011 and 2023 were included in the analysis. Twenty-four-hour milk production measurements were conducted using the test weighing method, and milk removal frequencies were recorded. Mothers completed questionnaires regarding demographic, obstetric and infant details. Linear and logistic regression models were used to determine maternal and infant factors associated with milk production. Here we show that increasing maternal age and BMI are associated with low milk production. Moreover, larger pre-pregnancy breast volume and breast growth are associated with both higher BMI and milk production. Women who are older, have an obese BMI and who have minimal pre-pregnancy breast volume and breast growth should be provided with antenatal screening and breastfeeding support as they are more likely to experience low milk production.

Fast, One‐Step In Situ Synthesis of a Hierarchical Sn4+‐Doped TiNb2O7 Nanosphere as a High‐Performance Anode Material

AbstractTitanium niobium oxide (TNO) exhibits great potential as a lithium‐ion battery anode due to its high capacity, minimal volume change during cycling, and safe good operation characteristic enabled from its voltage profile. However, its intrinsically low electronic and ionic conductivity hinders its potential for practical applications. This work proposes a facile coprecipitation method to address these limitations by incorporating a nano‐macro structure and in situ Sn ion doping into bulk TNO. This approach ensures homogeneous integration of TNO precursors and the Sn dopant at a molecular level within the co‐precipitation nanoparticles. Additionally, the use of low toxicity solvents facilitate scalability of the synthesis process. Excellent rate capability, high reversible capacities, and good capacity retention are achieved simultaneously due to synergistic effects of the bulk doping, which expands the crystal volume and enhances Li+ diffusion, combined with abundant surface area of the nano‐macro structures. The specific capacity of Sn‐doped TNO nanospheres remains at 180 mAh/g at a high current density of 40 C (1 C=400 mA g−1), which is nearly four times higher than that of undoped samples. Furthermore, the cyclic voltammetry analysis at various scanning rates reveals an increased Li+ diffusion rate in Sn doped titanium niobium dioxide.

Quantification of amino acids in small volumes of palm sweat samples

This study investigates the significance of quantifying amino acids in minute sweat volumes using high-performance liquid chromatography with fluorescence detection. Sweat, a valuable biofluid for non-invasive health monitoring, provides real-time insights into physiological changes. Amino acids, which are critical for various physiological processes, are key to protein synthesis and cellular regulation. Therefore, analyzing sweat's amino acid profiles can offer insights into metabolic states, exercise-induced stress, and potential biomarkers for health conditions. For sensitive analysis, amino acids were derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F), followed by liquid chromatographic separation on an octadecylsilyl column and fluorescence detection. The developed method was validated and applied to human sweat samples, enabling the quantification of 14 amino acids. The most abundant amino acids in the samples were serine, glycine, and alanine, which aligns with prior studies. This method offers a non-invasive and efficient way to screen for diseases by detecting amino acids in sweat, even with minimal sweat volumes. The approach could also be used to analyze other biomolecules in sweat, expanding its potential applications.

Log canonical pairs with conjecturally minimal volume

Log canonical pairs with conjecturally minimal volume

Modular Chip-Based nanoSFC-MS for Ultrafast Separations.

This study presents the development of a miniaturized device for supercritical fluid chromatography coupled with mass spectrometry. The chip-based, modular nanoSFC approach utilizes a particle-packed nanobore column embedded between two monolithically structured glass chips. A microtee in the pre-column section ensures picoliter sample loads onto the column, while a microcross chip structure fluidically controls the column backpressure. The restrictive emitter and the minimal post-column volume of 16 nL prevent mobile phase decompression and analyte dilution, maintaining chromatographic integrity during transfer to the atmospheric pressure MS interface. This facilitates high-speed chiral separations in less than 80 s with high reproducibility.

Portable Microfluidic Viscometer for Formulation Development and in Situ Quality Control of Protein and Antibody Solutions.

Viscosity of protein solutions is a critical product quality attribute for protein therapeutics such as monoclonal antibodies. Here we introduce a portable single-use analytical chip-based viscometer for determining the viscosity of protein solutions using low sample volumes of 10 μL. Through the combined use of a microfluidic viscometer, a smartphone camera for image capture, and an automated data processing algorithm for the calculation of the viscosity of fluids, we enable measurement of viscosity of multiple samples in parallel. We first validate the viscometer using glycerol-water mixtures and subsequently demonstrate the ability to perform rapid characterization of viscosity in four different monoclonal antibody formulations in a broad concentration (1 to 320 mg/mL) and viscosity (1 to 600 cP) range, showing excellent agreement with values obtained by a conventional cone-plate rheometer. Not only does the platform offer benefits of viscosity measurements using minimal sample volumes, but enables higher throughput compared to gold-standard methodologies owing to multiplexing of the measurement and single-use characteristics of the viscometer, thus showing great promise in developability studies. Additionally, as our platform has the capability of performing viscosity measurements at the point of sample collection, it offers the opportunity to employ viscosity measurement as an in situ quality control of therapeutic proteins and antibodies.

Acoustofluidic-based therapeutic apheresis system

Therapeutic apheresis aims to selectively remove pathogenic substances, such as antibodies that trigger various symptoms and diseases. Unfortunately, current apheresis devices cannot handle small blood volumes in infants or small animals, hindering the testing of animal model advancements. This limitation restricts our ability to provide treatment options for particularly susceptible infants and children with limited therapeutic alternatives. Here, we report our solution to these challenges through an acoustofluidic-based therapeutic apheresis system designed for processing small blood volumes. Our design integrates an acoustofluidic device with a fluidic stabilizer array on a chip, separating blood components from minimal extracorporeal volumes. We carried out plasma apheresis in mouse models, each with a blood volume of just 280 μL. Additionally, we achieved successful plasmapheresis in a sensitized mouse, significantly lowering preformed donor-specific antibodies and enabling desensitization in a transplantation model. Our system offers a new solution for small-sized subjects, filling a critical gap in existing technologies and providing potential benefits for a wide range of patients.

Electrochemical Detection of NT-Probnp Using High Performance Fully Inkjet-Printed Organic Electrochemical Transistors

Cardiovascular diseases are the number one cause of death worldwide, with Heart Failure (HF) accounting for a third of these fatalities. Therefore, there is a growing need for a point-of-care (POC) device capable of providing timely and accurate information on HF to minimize its impact on patients. N-terminal pro-B-type natriuretic peptide (NT-proBNP), released by myocardial cells in the blood in response to stress or strain, is regarded as the gold standard biomarker for HF management given its superior clinical relevance in diagnosis, prognosis, and therapy. Electrochemical potentiometric biosensors are promising alternatives to traditional analytical methods for biomarker detection. In particular, organic electrochemical transistors (OECTs) have garnered increased attention due to their ability to interface bodily fluids by simply operating inside an ionic environment. Additionally, they possess inherent transistor-specific amplification capabilities represented by the transconductance (gm), shown to scale with the thickness of the semiconducting channel, yielding values that are orders of magnitudes higher than those of field effect transistors (FETs). This feature enables OECTs to detect and amplify the presence of the target molecule without relying on complementary methodologies.HF patients lack self-operated and reliable POC devices that can provide immediate information about their health ensuring clinical accuracy for diagnosis and intervention. While several methods have been proposed, they fail to combine self-operation, speed, low-cost, and clinical accuracy. In this work, we aim to develop a POC HF sensor that can detect and quantify NT-proBNP levels in a finger prick blood volume, all while being cheap to fabricate, easy to operate, and rapid in providing results.OECTs were fabricated using inkjet-printing. First, the source, drain, and gate (2.5x2.5 mm) were patterned using a conductive gold nanoparticle ink. Subsequently the leads were insulated with polyimide, after which PEDOT:PSS was deposited to form the semi-conducting channel (15x400µm). Antibody immobilization for NT-proBNP detection was achieved by chemical functionalization of either the channel or the gate. To functionalize the channel, the PEDOT:PSS surface was treated with oxygen plasma to introduce hydroxyl groups. The following steps included silanization, then streptavidin grafting by immersion, and finally, antibody immobilization using biotinylated anti-NT-proBNP antibodies. To functionalize the gate, a quick three step protocol was adapted by employing thiolated-biotinylated-Polyethylene Glycol followed by streptavidin and then biotinylated antibodies. Surface functionalization, in both cases, was verified using electrochemical impedance spectroscopy (EIS). To detect the presence and quantify the levels of NT-proBNP using the realized OECT, several concentrations of NT-proBNP were prepared in PBS and tris-base buffer (pH=8.5) and introduced into the device sensing area. The different concentrations were distinguished through scanning of the transfer characteristic at drain-source voltages (VDS)=-0.05V or -0.5V and gate-source voltages (VGS)=0 to 0.8V.The developed biosensor has a miniaturized active recording area, enabling the use of minimal volumes to operate and detect NT-proBNP. The functionalization of either the in-plane gold gate or the PEDOT:PSS channel was validated by an increase in the electric impedance of the system at every step. Repetitive transfer characteristics scans revealed better stability at -0.05 VDS compared to -0.5 VDS, which is attributed to decreased channel current, and subsequently, preserved channel integrity in solution at the lower bias. The latter increases channel stability, but decreases gm, yet remains sufficiently high to successfully detect NT-proBNP at clinically relevant concentrations (0 to 1000 pg/ml). Functionalizing the gate led to a linearity of 95%, and a decrease in variability across trials compared to functionalizing the channel which can be attributed to the smaller detection area and better reactivity. The sensor also demonstrated selectivity by exhibiting a stronger response to NT-proBNP compared to BSA (a non-specific protein) proving the effectiveness of the chemical functionalization, which is particularly important when using the sensor with a complex solution like blood.In this work, we have developed an electrochemical potentiometric solution towards HF POC applications, capable of quantifying NT-proBNP in microvolumes at clinically relevant concentrations with high sensitivity, specificity, and repeatability. The adapted microfabrication methodology provides a cheap and quick approach for producing high performing sensors, rendered sensitive to HF biomarkers by chemical modification. The functionalization was found to be efficient and faster when applied at the gate instead of the channel given the versatile nature of the in-plane gate and the size-dependent performance limitations of the channel. The successful bedside integration of such technology holds promise in reducing HF mortality by enabling early diagnosis and immediate intervention, improving disease progression and management, and facilitating personalized strategies for prognosis, therapy, and prevention.