A Pumpless Microfluidic Neonatal Lung Assist Device for Support of Preterm Neonates in Respiratory Distress

Premature neonates suffer from respiratory morbidity as their lungs are immature, and current supportive treatment such as mechanical ventilation or extracorporeal membrane oxygenation causes iatrogenic injuries. A non-invasive and biomimetic concept known as the "artificial placenta" (AP) would be beneficial to overcome complications associated with the current respiratory support of preterm infants. Here, a pumpless oxygenator connected to the systemic circulation supports the lung function to relieve respiratory distress. In this paper, the first successful operation of a microfluidic, artificial placenta type neonatal lung assist device (LAD) on a newborn piglet model, which is the closest representation of preterm human infants, is demonstrated. This LAD has high oxygenation capability in both pure oxygen and room air as the sweep gas. The respiratory distress that the newborn piglet is put under during experimentation, repeatedly and over a significant duration of time, is able to be relieved. These findings indicate that this LAD has a potential application as a biomimetic artificial placenta to support the respiratory needs of preterm neonates.

π-SACS: pH Induced Self-Assembled Cell Sheets Without the Need for Modified Surfaces

The ability to form tissue-like constructs that have high cell density with proper cell-cell and cell-ECM interactions is critical for many applications including tissue models for drug discovery and tissue regeneration. Newly emerging bioprinting methods sometimes lack the high cellular density needed to provide biophysical cues to orchestrate cellular behavior to recreate tissue architecture and function. Alternate methods using self-assembly can be used to create tissue-like constructs with high cellular density and well-defined microstructure in the form of spheroids, organoids, or cell sheets. Cell sheets have a particularly interesting architecture in the context of tissue regeneration and repair as they can be applied as patches to integrate with surrounding tissues. Until now, the preparation of these sheets has involved culturing on specialized substrates that can be triggered by temperature or phase change (hydrophobic to hydrophilic) to release cells growing on them and form sheets. Here a new technique is proposed that allows delamination of cells and secreted ECM and rapid self-assembly into a cell sheet using a simple pH trigger and without the need to use responsive surfaces or applying external stimuli such as electrical and magnetic fields, only with routine tissue culture plates. This technique can be used with cells that are capable of syncytialization and fusion such as skeletal muscle cells and placenta cells. Using C2C12 myoblast cells we show that the pH trigger induces a rapid delamination of the cells as a continuous layer that self-assembles into a thick dense sheet. The delamination process has little effect on cell viability and maturation and preserves the ECM components that allow sheets to adhere to each other within a short incubation time enabling formation of thicker constructs when multiple sheets are stacked (double- and quadruple-layer constructs are formed here). These thick grafts can be used for regeneration purposes or as in vitro models.

Tissue-in-a-Tube: three-dimensional in vitro tissue constructs with integrated multimodal environmental stimulation

Three-dimensional (3D) in vitro tissue models are superior to two-dimensional (2D) cell cultures in replicating natural physiological/pathological conditions by recreating the cellular and cell-matrix interactions more faithfully. Nevertheless, current 3D models lack either the rich multicellular environment or fail to provide appropriate biophysical stimuli both of which are required to properly recapitulate the dynamic in vivo microenvironment of tissues and organs. Here, we describe the rapid construction of multicellular, tubular tissue constructs termed Tissue-in-a-Tube using self-assembly process in tubular molds with the ability to incorporate a variety of biophysical stimuli such as electrical field, mechanical deformation, and shear force of the fluid flow. Unlike other approaches, this method is simple, requires only oxygen permeable silicone tubing that molds the tissue construct and thin stainless-steel pins inserted in it to anchor the construct and could be used to provide electrical and mechanical stimuli, simultaneously. The annular region between the tissue construct and the tubing is used for perfusion. Highly stable, macroscale, and robust constructs anchored to the pins form as a result of self-assembly of the extracellular matrix (ECM) and cells in the bioink that is filled into the tubing. We demonstrate patterning of grafts containing cell types in the constructs in axial and radial modes with clear interface and continuity between the layers. Different environmental factors affecting cell behavior such as compactness of the structure and size of the constructs can be controlled through parameters such as initial cell density, ECM content, tubing size, as well as the distance between anchor pins. Using connectors, network of tubing can be assembled to create complex macrostructured tissues (centimeters length) such as fibers that are bifurcated or columns with different axial thicknesses which can then be used as building blocks for biomimetic constructs or tissue regeneration. The method is versatile and compatible with various cell types including endothelial, epithelial, skeletal muscle cells, osteoblast cells, and neuronal cells. As an example, long mature skeletal muscle and neuronal fibers as well as bone constructs were fabricated with cellular alignment dictated by the applied electrical field. The versatility, speed, and low cost of this method is suited for widespread application in tissue engineering and regenerative medicine.

Electrokinetic transport and distribution of antibacterial nanoparticles for endodontic disinfection

AIM

To assess a novel, noninvasive intervention capable of mobilizing charged antibacterial nanoparticles to the apical portions of the root canal system, utilizing the principles of electrokinetics.

METHODS

Experiments were conducted in three stages. Stage-1: A computer model was generated to predict and visualize the electric field and current density distribution generated by the proposed intervention. Stage-2: Transport of chitosan nanoparticles (CSnp) was evaluated qualitatively using a transparent microfluidic model with fluorescent-labelled CSnp. Stage-3: An ex vivo model was utilized to study the antimicrobial efficacy of the proposed treatment against 3-week-old monospecies E. faecalis biofilms. Scanning electron microscopy (SEM) was also utilized in this stage to confirm the deposition of CSnp.

RESULTS

The results of the computer simulations predicted an electric field and current density that reach their maxima at the apical constriction of the root canal. Correspondingly, the microfluidic experiments demonstrated rapid, controlled CSnp transport throughout the simulated root canal anatomy with subsequent distribution and deposition in the apical constriction as well as periapical regions. Infected root canals when subjected to the novel treatment method resulted in a mean bacterial reduction of 2.1 log CFU. SEM analysis revealed electrophoretic deposition of chitosan nanoparticles onto the root canal dentine walls in the apical region.

CONCLUSION

The findings from this study demonstrate that the combination of cationic antibacterial nanoparticles with a low-intensity electric field results in particle transportation (electrophoresis) and deposition within the root canal. This results in a synergistic antibiofilm efficacy and has the potential to enhance root canal disinfection.

Influence of wastewater microbial community on the performance of miniaturized microbial fuel cell biosensor

Microbial fuel cells (MFCs) based sensors had been studied in measuring biochemical oxygen demand (BOD) or the equivalent chemical oxygen demand (COD) recently. Limited attention has been paid to the effect of the microbial communities in wastewater on the responses of these sensors. This study systematically evaluated, for the first time, the effect of wastewater samples from a variety of sources on the electrical response of a micro-fabricated double-chamber MFC device. It was found that the response of the MFC is positively correlated with the bacterial composition, in particular electroactive bacteria. The presence of aerobic bacteria in the sample reduces the current generation. These findings indicated that the bacterial content of the water sample could be a significant interference source and must be considered in the use of µMFC-based sensors. Filtering samples may be effective in improving the reliability of these microsensors.

Microfluidic Device for Microinjection of Caenorhabditis elegans

Microinjection is an established and reliable method to deliver transgenic constructs and other reagents to specific locations in C. elegans worms. Specifically, microinjection of a desired DNA construct into the distal gonad is the most widely used method to generate germ-line transformation of C. elegans. Although, current C. elegans microinjection method is effective to produce transgenic worms, it requires expensive multi degree of freedom (DOF) micromanipulator, careful injection alignment procedure and skilled operator, all of which make it slow and not suitable for scaling to high throughput. A few microfabricated microinjectors have been developed recently to address these issues. However, none of them are capable of immobilizing a freely mobile animal such as C. elegans worm using a passive immobilization mechanism. Here, a microfluidic microinjector was developed to passively immobilize a freely mobile animal such as C. elegans and simultaneously perform microinjection by using a simple and fast mechanism for needle actuation. The entire process of the microinjection takes ~30 s which includes 10 s for worm loading and aligning, 5 s needle penetration, 5 s reagent injection and 5 s worm unloading. The device is suitable for high-throughput and can be potentially used for creating transgenic C. elegans.

Electroplating of Multiple Materials in Parallel Using Patterned Gels with Applications in Electrochemical Sensing

Electrodeposition is a versatile technique for the fabrication of electrodes in micro-electroanalytical devices. Conductive but low-cost materials, such as copper, can be coated with functional yet higher-cost materials such as gold or silver using electrodeposition to lower the overall cost while maintaining functionality. When the electrodeposition of multiple materials is required, current methods use a multistep process that deposits one material at a time, which requires a significant amount of time and a significant number of steps. Additionally, they use a large volume of electrolytes suitable for coating large objects, which is wasteful and unnecessary for the prototyping or coating of microelectrodes with a small area. In this paper, a new method of electroplating is introduced in which we used gels to immobilize and pattern electroplating electrolytes on a substrate surface. Agarose, as an immobilizing medium, enables the immersion of the substrate in a common working electrolyte without cross-mixing different electrolytes. We demonstrate the printing of jelly electrolytes by using spot-dispensing or microfluidic flow. Xurographically patterned films laminated on the substrate function as a mask and confine the printed gels to desired locations. After printing, the substrate is placed in a common working electrolyte container, and multimaterial patterns are produced through the application of an electrical current in a single step.

Chloroform and desflurane immobilization with recovery of viable Drosophila larvae for confocal imaging

Imaging of living, intact Drosophila larvae is challenged if normal bodily function must be observed or when healthy larvae must be recovered for subsequent studies. Here, we describe a simple and short protocol that employs transient airborne chloroform or desflurane (1,2,2,2-tetrafluoroethyl difluoromethyl ether) to efficiently immobilize larvae without the use of manipulation devices, vaporizers or imaging chambers. This non-lethal method allows the use of anesthetics while allowing tracking of individual Drosophila into adulthood for follow-up experiments. At dosages sufficient to immobilize larvae, Desflurane, but not chloroform reduced the central nervous system response to auditory stimulus. Desflurane doses were sufficient to arrest the heart, however significant rapid recovery was observed. With our method, chloroform provided more rapid anesthesia but slower recovery than Desflurane. Without specialized hardware, this technique allows for repeated imaging of living Drosophila larvae.

A rapid biofabrication technique for self-assembled collagen-based multicellular and heterogeneous 3D tissue constructs

Although monolayer cell culture models are considered as gold standard for in vitro modeling of pathophysiological events, they cannot reconstruct in vivo like gradient of gases and nutrients and lack proper cell-cell and cell-matrix interactions. Spherical cellular aggregates, otherwise known as multicellular spheroids, are widely used as three-dimensional in vitro models to mimic natural in vivo cellular microenvironment for applications such as drug screening. Although very useful, the previously established techniques are limited to low cell numbers, their processes are usually slow, and sometimes show limitations in terms of the cell type that can be used. Here, a versatile technique based on rapid self-assembly of cells and extracellular matrix material in different shapes using microfabricated molds is introduced to form multicellular tissue constructs. The self-assembly process takes less than 6 h and produces a mechanically robust tissue construct that could be handled easily. We demonstrate that a variety of shapes including spherical, cuboidal, dumbbell- and cross-like shapes could be fabricated using this approach. Interestingly, the structures formed with non-spherical shapes were able to retain that shape even after removal from the molds and during long term cell culture. This versatile approach is applicable to a variety of cell types (breast cancer cell lines MCF-7, MDA-MB-321, Hs-578T; osteosarcoma cell line SaOS-2; endothelial cell line HUVEC) as well as a range of cell numbers (10⁴-10⁶). Furthermore, we also show that the constructs could be spatially patterned to position various cell types in a precisely controlled way. Such heterogeneous constructs that are formed provide physiologically relevant cell densities, 3D structure as well as close positioning of multiple types of cells that are not possible using other fabrication approaches. This fabrication approach will find significant applications in developing 3D cell culture models for drug discovery as well as tissue grafts for implantation. STATEMENT OF SIGNIFICANCE: In this manuscript we describe a method for rapid formation of tissue constructs (6 h as opposed to several days for current state of art methods). We also identify the essential factors needed for such a rapid consolidation into a construct. We demonstrate the ability to form non-spherical constructs of various shapes that retain their shape over long term as opposed to those formed with current state of art that lose their shape during long time cell culture. We also show the ability to form precise heterogeneous constructs consisting of multiple cell types and with well-defined interfaces that are not possible with current state of art methods. This method could be used with a wide variety of cell types and are mechanically robust within 6 h to be handled with tweezers. We believe that such multicellular, heterogeneous constructs would be of significant use to biologists and drug discovery researchers investigating mechanisms involved in diseases processes or the effect of drug on them.

An ultra-thin, all PDMS-based microfluidic lung assist device with high oxygenation capacity

Preterm neonates with immature lungs require a lung assist device (LAD) to maintain oxygen saturation at normal levels. Over the last decade, microfluidic blood oxygenators have attracted considerable interest due to their ability to incorporate unique biomimetic design and to oxygenate in a physiologically relevant manner. Polydimethylsiloxane (PDMS) has become the main material choice for these kinds of devices due to its high gas permeability. However, fabrication of large area ultrathin microfluidic devices that can oxygenate sufficient blood volumes at clinically relevant flow rates, entirely made of PDMS, have been difficult to achieve primarily due to failure associated with stiction of thin PDMS membranes to each other at undesired locations during assembly. Here, we demonstrate the use of a modified fabrication process to produce large area ultrathin oxygenators entirely made of PDMS and robust enough to withstand the hydraulic conditions that are encountered physiologically. We also demonstrate that a LAD assembled from these ultrathin double-sided microfluidic blood oxygenators can increase the oxygen saturation level by 30% at a flow rate of 30 ml/min and a pressure drop of 21 mm Hg in room air which is adequate for 1 kg preterm neonates. In addition, we demonstrated that our LAD could withstand high blood flow rate of 150 ml/min and increase oxygen saturation by 26.7% in enriched oxygen environment which is the highest gas exchange reported so far by any microfluidic-based blood oxygenators. Such performance makes this LAD suitable to provide support to 1 kg neonate suffering from respiratory distress syndrome.

3D bioprinting of heterogeneous bi- and tri-layered hollow channels within gel scaffolds using scalable multi-axial microfluidic extrusion nozzle

One of the primary focuses in recent years in tissue engineering has been the fabrication and integration of vascular structures into artificial tissue constructs. However, most available methodologies lack the ability to create multi-layered concentric conduits inside natural extracellular matrices (ECMs) and gels that replicate more accurately the hierarchical architecture of biological blood vessels. In this work, we present a new microfluidic nozzle design capable of multi-axial extrusion in order to 3D print and pattern bi- and tri-layered hollow channel structures. This nozzle allows, for the first time, for these structures to be embedded within layers of gels and ECMs in a fast, simple and low-cost manner. By varying flow rates (1-6 ml min^-1), printspeeds (1-16 m min^-1), and material concentration (25-175 mM and 1.5%-2.5% for calcium chloride and alginate, respectively) we are able to accurately determine the operational printing range as well as achieve a wide range of conduit dimensions (0.69-2.31 mm) that can be printed within a few seconds. Our scalable design allows for multi-axial extrusion and versatility in material incorporation in order to create heterogeneous structures. We demonstrate the ability to print distinct concentric layers of different cell types, namely endothelial cells and fibroblasts. By incorporating various layers of different cell-friendly materials (such as collagen and fibrin) alongside materials with high mechanical strength (i.e. alginate), we were able to increase long-term cell viability and growth without compromising the structural integrity. In this way, we can improve cellular adhesion in our biocompatible constructs as well as allow them to remain structurally sound. We are able to realize complex heterogeneous, hierarchical architectures that have strong potential for use not only in vascular tissue applications, but also in other artificially fabricated tubular or fiber-like structures such as skeletal muscle or nerve conduits.

An ultra-thin highly flexible microfluidic device for blood oxygenation

Many neonates who are born premature suffer from respiratory distress syndrome (RDS) for which mechanical ventilation and an extracorporeal membrane oxygenation (ECMO) device are used in treatment. However, the use of these invasive techniques results in higher risk of complications like bronchopulmonary dysplasia or requires surgery to gain vascular access. An alternative biomimetic approach is to use the umbilical cord as a vascular access and to connect a passive device to the baby that functions like a placenta. This concept, known as the artificial placenta, provides enough oxygenation and causes minimal distress or complications. Herein, we have developed a new artificial placenta-type microfluidic blood oxygenator (APMBO) with high gas exchange, low priming volume and low hydraulic resistance such that it can be operated only by pressure differential provided by the baby's heart. Mimicking the placenta, we have made our new device ultra-thin and flexible so that it can be folded into a desired shape without losing its capability for gas exchange and achieve a compact form factor. The ability to fold allowed optimization of connectors and reduced the overall priming volume to the sub-milliliter range while achieving a high oxygen uptake which would be sufficient for preterm neonates with a birth-weight of around 0.5 kg.

C. elegans MANF Homolog Is Necessary for the Protection of Dopaminergic Neurons and ER Unfolded Protein Response

Neurotrophic factors (NTFs) are important for the development, function, and survival of neurons in the mammalian system. Mesencephalic astrocyte-derived neurotrophic factor (MANF) and cerebral dopamine neurotrophic factor (CDNF) are two recently identified members of a novel family of NTFs in vertebrates that function to protect dopaminergic neurons. Although these genes are conserved across eukaryotes, their mechanism of neuroprotection is not fully understood. Sequence searches for MANF/CDNF homologs in invertebrates have identified a single ortholog that is most related to MANF. Here we report the in vivo characterization of the MANF gene, manf-1, in the nematode Caenorhabditis elegans. We found that manf-1 mutants have an accelerated, age-dependent decline in the survival of dopaminergic neurons. The animals also show increased endoplasmic reticulum (ER) stress, as revealed by reporter gene expression analysis of hsp-4, an ER chaperone BiP/GRP78 homolog, suggesting that a failure to regulate the ER unfolded protein response (ER-UPR) may be a contributing factor to dopaminergic neurodegeneration. Expression studies of manf-1 revealed that the gene is broadly expressed in a pattern that matches closely with hsp-4. Consistent with the requirements of manf-1 in the ER-UPR, we found that aggregates of α-Synuclein, a major constituent of Lewy bodies, were significantly increased in body wall muscles of manf-1 mutant animals. Overall, our work demonstrates the important role of manf-1 in dopaminergic neuronal survival and the maintenance of ER homeostasis in C. elegans.

An artificial placenta type microfluidic blood oxygenator with double-sided gas transfer microchannels and its integration as a neonatal lung assist device

Preterm neonates suffering from respiratory distress syndrome require assistive support in the form of mechanical ventilation or extracorporeal membrane oxygenation, which may lead to long-term complications or even death. Here, we describe a high performance artificial placenta type microfluidic oxygenator, termed as a double-sided single oxygenator unit (dsSOU), which combines microwire stainless-steel mesh reinforced gas permeable membranes on both sides of a microchannel network, thereby significantly reducing the diffusional resistance to oxygen uptake as compared to the previous single-sided oxygenator designs. The new oxygenator is designed to be operated in a pumpless manner, perfused solely due to the arterio-venous pressure difference in a neonate and oxygenate blood through exposure directly to ambient atmosphere without any air or oxygen pumping. The best performing dsSOUs showed up to ∼343% improvement in oxygen transfer compared to a single-sided SOU (ssSOU) with the same height. Later, the dsSOUs were optimized and integrated to build a lung assist device (LAD) that could support the oxygenation needs for a 1-2 kg neonate under clinically relevant conditions for the artificial placenta, namely, flow rates ranging from 10 to 60 ml/min and a pressure drop of 10-60 mmHg. The LAD provided an oxygen uptake of 0.78-2.86 ml/min, which corresponded to the increase in oxygen saturation from 57 ± 1% to 93%-100%, under pure oxygen environment. This microfluidic lung assist device combines elegant design with new microfabrication methods to develop a pumpless, microfluidic blood oxygenator that is capable of supporting 30% of the oxygen needs of a pre-term neonate.

Extracellular matrix surface regulates self-assembly of three-dimensional placental trophoblast spheroids

The incorporation of the extracellular matrix (ECM) is essential for generating in vitro models that truly represent the microarchitecture found in human tissues. However, the cell-cell and cell-ECM interactions in vitro remains poorly understood in placental trophoblast biology. We investigated the effects of varying the surface properties (surface thickness and stiffness) of two ECMs, collagen I and Matrigel, on placental trophoblast cell morphology, viability, proliferation, and expression of markers involved in differentiation/syncytial fusion. Most notably, thicker Matrigel surfaces were found to induce the self-assembly of trophoblast cells into 3D spheroids that exhibited thickness-dependent changes in viability, proliferation, syncytial fusion, and gene expression profiles compared to two-dimensional cultures. Changes in F-actin organization, cell spread morphologies, and integrin and matrix metalloproteinase gene expression profiles, further reveal that the response to surface thickness may be mediated in part through cellular stiffness-sensing mechanisms. Our derivation of self-assembling trophoblast spheroid cultures through regulation of ECM surface alone contributes to a deeper understanding of cell-ECM interactions, and may be important for the advancement of in vitro platforms for research or diagnostics.

Steel reinforced composite silicone membranes and its integration to microfluidic oxygenators for high performance gas exchange

Respiratory distress syndrome (RDS) is one of the main causes of fatality in newborn infants, particularly in neonates with low birth-weight. Commercial extracorporeal oxygenators have been used for low-birth-weight neonates in neonatal intensive care units. However, these oxygenators require high blood volumes to prime. In the last decade, microfluidics oxygenators using enriched oxygen have been developed for this purpose. Some of these oxygenators use thin polydimethylsiloxane (PDMS) membranes to facilitate gas exchange between the blood flowing in the microchannels and the ambient air outside. However, PDMS is elastic and the thin membranes exhibit significant deformation and delamination under pressure which alters the architecture of the devices causing poor oxygenation or device failure. Therefore, an alternate membrane with high stability, low deformation under pressure, and high gas exchange was desired. In this paper, we present a novel composite membrane consisting of an ultra-thin stainless-steel mesh embedded in PDMS, designed specifically for a microfluidic single oxygenator unit (SOU). In comparison to homogeneous PDMS membranes, this composite membrane demonstrated high stability, low deformation under pressure, and high gas exchange. In addition, a new design for oxygenator with sloping profile and tapered inlet configuration has been introduced to achieve the same gas exchange at lower pressure drops. SOUs were tested by bovine blood to evaluate gas exchange properties. Among all tested SOUs, the flat design SOU with composite membrane has the highest oxygen exchange of 40.32 ml/min m². The superior performance of the new device with composite membrane was demonstrated by constructing a lung assist device (LAD) with a low priming volume of 10 ml. The LAD was achieved by the oxygen uptake of 0.48-0.90 ml/min and the CO₂ release of 1.05-2.27 ml/min at blood flow rates ranging between 8 and 48 ml/min. This LAD was shown to increase the oxygen saturation level by 25% at the low pressure drop of 29 mm Hg. Finally, a piglet was used to test the gas exchange capacity of the LAD in vivo. The animal experiment results were in accordance with in-vitro results, which shows that the LAD is capable of providing sufficient gas exchange at a blood flow rate of ∼24 ml/min.

Reagent-Free Quantification of Aqueous Free Chlorine via Electrical Readout of Colorimetrically Functionalized Pencil Lines

Colorimetric methods are commonly used to quantify free chlorine in drinking water. However, these methods are not suitable for reagent-free, continuous, and autonomous applications. Here, we demonstrate how functionalization of a pencil-drawn film with phenyl-capped aniline tetramer (PCAT) can be used for quantitative electric readout of free chlorine concentrations. The functionalized film can be implemented in a simple fluidic device for continuous sensing of aqueous free chlorine concentrations. The sensor is selective to free chlorine and can undergo a reagent-free reset for further measurements. Our sensor is superior to electrochemical methods in that it does not require a reference electrode. It is capable of quantification of free chlorine in the range of 0.1-12 ppm with higher precision than colorimetric (absorptivity) methods. The interactions of PCAT with the pencil-drawn film upon exposure to hypochlorite were characterized spectroscopically. A previously reported detection mechanism relied on the measurement of a baseline shift to quantify free chlorine concentrations. The new method demonstrated here measures initial spike size upon exposure to free chlorine. It relies on a fast charge built up on the sensor film due to intermittent PCAT salt formation. It has the advantage of being significantly faster than the measurement of baseline shift, but it cannot be used to detect gradual changes in free chlorine concentration without the use of frequent reset pulses. The stability of PCAT was examined in the presence of free chlorine as a function of pH. While most ions commonly present in drinking water do not interfere with the free chlorine detection, other oxidants may contribute to the signal. Our sensor is easy to fabricate and robust, operates reagent-free, and has very low power requirements and is thus suitable for remote deployment.

A microfluidic device for rapid quantification of cell-free DNA in patients with severe sepsis

A rapid and accurate method to identify severe sepsis patients at high risk of death is critically needed for clinical practice. In a recent study, the concentration of cell-free DNA (cfDNA) in blood was found to be a prognostic indicator for ICU mortality in patients with severe sepsis. However, current DNA quantification techniques are time-consuming and involve extensive sample preparation. In this paper, we demonstrate a low-cost microfluidic device capable of rapid quantification of cfDNA in a small droplet (<10 μl) of blood plasma and whole blood in 5 min using only electrical power. The cfDNA in samples is selectively labeled by PicoGreen and is extracted and concentrated by electrophoresis into a gel by application of a DC potential of 9 V. This device has potential as a prognostic tool for early and rapid assessment of septic patients.

Low-temperature solution processing of palladium/palladium oxide films and their pH sensing performance

Highly sensitive, easy-to-fabricate, and low-cost pH sensors with small dimensions are required to monitor human bodily fluids, drinking water quality and chemical/biological processes. In this study, a low-temperature, solution-based process is developed to prepare palladium/palladium oxide (Pd/PdO) thin films for pH sensing. A precursor solution for Pd is spin coated onto pre-cleaned glass substrates and annealed at low temperature to generate Pd and PdO. The percentages of PdO at the surface and in the bulk of the electrodes are correlated to their sensing performance, which was studied by using the X-ray photoelectron spectroscope. Large amounts of PdO introduced by prolonged annealing improve the electrode's sensitivity and long-term stability. Atomic force microscopy study showed that the low-temperature annealing results in a smooth electrode surface, which contributes to a fast response. Nano-voids at the electrode surfaces were observed by scanning electron microscope, indicating a reason for the long-term degradation of the pH sensitivity. Using the optimized annealing parameters of 200°C for 48 h, a linear pH response with sensitivity of 64.71±0.56 mV/pH is obtained for pH between 2 and 12. These electrodes show a response time shorter than 18 s, hysteresis less than 8 mV and stability over 60 days. High reproducibility in the sensing performance is achieved. This low-temperature solution-processed sensing electrode shows the potential for the development of pH sensing systems on flexible substrates over a large area at low cost without using vacuum equipment.

Hoare T, Jain SB, Hossain F, Mishra RK. A Novel Intranasal Spray Device for the Administration of Nanoparticles to Rodents

Experimental intranasal (IN) delivery of nanoparticle (NP) drug carriers is typically performed using a pipette with or without anesthesia, a technique that may be a poor simulation of practical IN administration of drug-loaded NPs in humans. Existing IN spray devices suffer from drawbacks in terms of variability in dose-control and spray duration as well as the application of nonuniform pressure fields when a NP-formulated drug is aerosolized. Furthermore, existing spray devices require large volumes that may not be available or may be prohibitively expensive to prepare. In response, we have developed a novel pneumatically driven IN spray device for the administration of NPs, which is capable of administering extremely small quantities (50–100 μl) of NP suspension in a fine spray that disperses the NPs uniformly onto the tissue. This device was validated using haloperidol-loaded Solanum tuberosum lectin (STL)-functionalized, poly(ethylene glycol)–block-poly(d,l-lactic-co-glycolic acid) (PEG–PLGA) NPs targeted for delivery to the brain for schizophrenia treatment. A pneumatic pressure of 100 kPa was found to be optimal to produce a spray that effectively aerosolizes NP suspensions and delivers them evenly to the olfactory epithelium. IN administration of STL-functionalized NPs using the IN spray device increased brain tissue haloperidol concentrations by a factor of 1.2–1.5× compared to STL-functionalized NPs administered IN with a pipette. Such improved delivery enables the use of lower drug doses and thus offers both fewer local side-effects and lower costs without compromising therapeutic efficacy.

Surface modification of poly(dimethylsiloxane) with a covalent antithrombin-heparin complex for the prevention of thrombosis: use of polydopamine as bonding agent

A modified poly(dimethyl siloxane) (PDMS) material is under development for use in an extracorporeal microfluidic blood oxygenator designed as an artificial placenta to treat newborn infants suffering from severe respiratory insufficiency. To prevent thrombosis triggered by blood-material contact, an antithrombin-heparin (ATH) covalent complex was coated on PDMS surface using polydopamine (PDA) as a "bioglue". Experiments using radiolabelled ATH showed that the ATH coating on PDA-modified PDMS remained substantially intact after incubation in plasma, 2% SDS solution, or whole blood over a three day period. The anticoagulant activity of the ATH-modified surfaces was also demonstrated: in contact with plasma the ATH-coated PDMS was shown to bind antithrombin (AT) selectively from plasma and to inhibit clotting factor Xa. It is concluded that modification of PDMS with polydopamine and ATH shows promise as a means of improving the blood compatibility of PDMS and hence of the oxygenator device.