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We developed a compact perfusion cell culture with integrated wireless detection device for real-time optical monitoring. The platform enables long-term cell growth and cytotoxicity assay where cell viability is quantified using AI software.

During the past decades, microdevices have been evaluated as a means to overcome challenges within oral drug delivery, thus improving bioavailability. Fabrication of microdevices is often limited to planar or simple 3D designs. Therefore, this work explores how microscale stereolithography 3D printing can be used to fabricate radiopaque microcontainers with enhanced mucoadhesive geometries, which can enhance bioavailability by increasing gastrointestinal retention. Ex vivo force measurements suggest increased mucoadhesion of microcontainers with adhering features, such as pillars and arrows, compared to a neutral design. In vivo studies, utilizing planar X-ray imaging, show the time-dependent gastrointestinal location of microcontainers, whereas computed tomography scanning and cryogenic scanning electron microscopy reveal information about their spatial dynamics and mucosal interactions, respectively. For the first time, the effect of 3D microdevice modifications on gastrointestinal retention is traced in vivo, and the applied methods provide a much-needed approach for investigating the impact of device design on gastrointestinal retention.

An astigmatic optical profilometer provides numerous advantages such as compact size, low cost, and high resolution. In 2018, a z -axis modulation mode of the astigmatic optical profilometer was developed to realize quantitative height measurement for a surface comprising complex materials. However, the current imaging rate of the z -axis modulation mode is time-consuming. In this article, a resonant scanner was proposed to execute a high-speed z -axis scanning motion. By inducing the resonant mode, the resonant scanner enabled both a large travel range of over 87 μ m and high oscillation frequency of 1.576 kHz. Additionally, a data analysis process was proposed to calibrate the nonlinear movement of the resonant scanner. Experimental results demonstrated that the developed optical profilometer successfully captured the quantitative height and reflectivity of the complex material comprising chrome patterns on a glass substrate. Furthermore, an imaging rate of 256 s/frame was achieved, which was approximately 50 times faster than that of a previous system employing a commercial flexure-guided scanner.

Two simple, mechanical modifications are introduced to a consumer-grade inkjet printer to greatly increase its applicability. First, roller isolation bars are added to unlock multiple prints on the same substrate without smearing. This enables printing on a diverse set of substrates (rigid, elastic, liquid, granular, and sticky). Second, spring loadings are added to increase the print precision up to 50-fold, which facilitates alignment to a pre-patterned substrate or between successive prints. Utilizing the expanded substrate compatibility and the increased print precision, we explore tunable loading of drug combinations into microdevices. This loading method has promising applications within point-of-care personalized medication. Furthermore, we show how inkjet printers with array-type printheads (in our case, 6 x 90 nozzles) allow for quasi-simultaneous loading of reactants into microfluidic systems. The ability to do a quasi-simultaneous introduction of chemicals may be particularly useful for studies of rapidly reacting systems of three or more reactants, where premature introduction can shift the initial conditions from the intended. We believe that our modifications to an affordable system will inspire researchers to explore the possibilities of inkjet printing even further.

In vitro release and dissolution models are widely used in the development phases of oral drug delivery systems to measure how an active pharmaceutical ingredient (API) is released from a dosage form. However, additional requirements for these models arise when evaluating probiotic dosage forms since they are often sensitive to temperature and oxygen levels. As a solution to this, we propose a custom-designed anaerobic in vitro release setup, made mainly by 3D printing and laser cutting, to function together with state-of-the-art pharmaceutical dissolution equipment – in this case, a microDISS Profiler™. The in vitro release model makes it possible to study the release rate of oxygen-sensitive probiotics in simulated intestinal conditions, while ensuring their survival due to the anaerobic conditions. This has not been possible so far since the available in vitro dissolution models have not been compatible with anaerobic conditions. With two different case studies, the developed model combined with a microDISS Profiler™ has proven capable of measuring the release of a probiotic and a small-molecule API from microdevices for oral drug delivery. Further, the model facilitated the survival of anaerobic bacteria present in the release medium.

Encapsulation of bacteria into a polymer matrix can potentially enhance the delivery of probiotics. In this study, we present a multilayer electrospun construct to facilitate enhanced delivery of probiotics, where the internal layer is loaded with bacterial cells and the external layers sandwich the internal layer for increased protection and potential mucoadhesion properties. In this proof of concept study, Lactobacillus rhamnosus GG (LGG), which is a robust and well-studied probiotic strain, was encapsulated into pullulan nanofibers, with two electrospun PLGA (Poly-lactic-co-glycolic acid) layers covering it. According to our in vitro study, there was a large decrease in the viability of LGG released from the monolayer sample (LGG:pullulan). However, the multilayer construct maintained excellent viability and an acceptable storage potential. Our in vivo competition study showed that LGG, delivered by multilayer construct, were able to survive intestinal transit and were recovered from all segments of the intestine. Not only did the multilayer construct perform as well as non-encapsulated spray-dried cells in terms of viability and establishment of LGG, but it also showed some cases of increased LGG colonization from fibers in jejunum and cecum compared to spray-dried LGG three days after dosage. We believe, the multilayer construct has the potential to enhance the delivery of the strains that require additional protection, and can benefit from mucus embedment with the help of the covering layers. Particularly, the use of electrospun fibers for the protection of next-generation probiotics sensitive to oxygen and/or gastric conditions could have major commercial interest.

8th World Conference on Photovoltaic Energy Conversion; 44-54, This work investigates the production and performance of p-type Inversion Layer (IL) Si solar cells, manufactured with an ion-injection technique that produces a highly charged dielectric nanolayer. Ions are applied to the front dielectric layer and then driven towards the c-Si/SiO2 interface by an electric field before stabilisation with an anneal. As this process can be performed in minutes at temperatures below 500 °C, it potentially provides a fast, yet controllable way for IL cell manufacturing. We demonstrate by simulations using Sentaurus TCAD that for the 1 ·cm p-type Si/thermal oxide model defined in this work, the sheet resistance of the field-induced electron layer can reach 1.1 k/sq in the dark by reducing band-tail interface state density to below 1014 eV-1cm-2 and increasing the dielectric charge density to above 2 × 1013 cm-2. Additionally, we present a proof-of-concept p-type IL cell on a non-gettered, non-hydrogenated substrate with an efficiency of 10.8%, and an open-circuit voltage (VOC) equivalent to that in a cell with a diffused phosphorous emitter. Lastly, we perform Sentaurus TCAD simulations to assess the efficiency potential of such IL cells. By incorporating optimal passivation, gettering, hydrogenation and metallisation, IL cells are predicted to reach an efficiency of 24.5% on 5 ·cm, and beyond 24.8% on 10 ·cm p-type substrates, provided the dielectric charge density reaches 2 × 1013 cm-2, which has been experimentally demonstrated to be possible. IL cells are therefore, in principle, a potential competitive candidate in the photovoltaic industry.

High-speed atomic force microscopes (HS-AFMs) with high temporal resolution enable dynamic phenomena to be visualized at nanoscale resolution. However, HS-AFMs are more complex and costlier than conventional AFMs, and particulars of an open-source HS-AFM controller have not been published before. These high entry barriers hinder the popularization of HS-AFMs in both academic and industrial applications. In addition, HS-AFMs generally have a small imaging area that limits the fields of implementation. This study presents an open-source controller that enables a low-cost simplified AFM to achieve a maximum tip-sample velocity of 5,093 µm/s (9.3 s/frame, 512 × 512 pixels), which is nearly 100 times higher than that of the original controller. Moreover, the proposed controller doubles the imaging area to 46.3 × 46.3 µm2 compared to that of the original system. The low-cost HS-AFM can successfully assess the severity of atopic dermatitis (AD) by measuring the nanotexture of human skin corneocytes in constant height DC mode. The open-source controller-based HS-AFM system costs less than $4,000, which provides resource-limited research institutes with affordable access to high-throughput nanoscale imaging to further expand the HS-AFM research community.

Trillions of USD have been dedicated to the development of consumer electronic technologies, to produce drones, wireless chargers, spy cameras, and DVD/Blu-ray optical data storage systems. Consequently, these have been perfected into compact, reliable, high-performance, and low-cost devices. This work reviews the complete repurposing (hacking) of consumer electronics for biomedical imaging and sensing applications.

In the pharmaceutical field, oral drug delivery devices continue to shrink down to the micrometer scale, driving a trending demand to investigate ex vivo mucoadhesive force down to the micro-Newton scale. However, owing to the limitation of measuring sensitivity, conventional methods (e.g., a texture analyzer) lack reliability while measuring forces in this range. Herein, we report on an open-source force analyzer that utilizes an optical-pickup-unit (from a DVD player) to detect cantilever-based force transducers and thereby, achieves a wide force-sensing range from 1.1 N to 0.99 nN. The cantilever force transducers can easily be adjusted to fit different force ranges by adjusting the steel shim, magnets, and 3D printed components. To validate the analyzer, we conducted a preliminary study to investigate the effect of time and humidity of mucoadhesion of porcine intestinal tissues. Besides, we measured the mucoadhesive force of a single oral drug delivery microdevice with an average force of 93.7 µN on the top sides of the device. This analyzer offers the possibility of measuring e.g. mucoadhesion of individual microdevices in the micro-Newton range. Hence, the analyzer can assist in the development of miniaturized oral drug delivery devices but has a much wider field of potential force sensing applications.

Interfacing electrochemical sensors in a lab-on-a-disc (LoD) system with a potentiostat is often tedious and challenging. We here present the first multichannel, modular, lightweight, and wirelessly powered, custom-built potentiostat-on-a-disc (PoD) for centrifugal microfluidic applications. The developed potentiostat is in the form factor of a typical digital video disc (DVD) and weighs only 127 g. The design of the potentiostat facilitates easy and robust interfacing with the electrodes in the LoD system, while enabling real-time electrochemical detection during rotation. The device can perform different electroanalytical techniques such as cyclic voltammetry, square wave voltammetry, and amperometry while being controlled by custom-made software. Measurements were conducted with and without rotation using both in-house fabricated and commercial electrodes. The performance of the PoD was in good agreement with the results obtained using a commercial potentiostat with a measured current resolution of 200 pA. As a proof of concept, we performed a real-time release study of an electrochemically active compound from microdevices used for drug delivery.

The production and performance of p-type inversion layer (IL) Si solar cells, manufactured with an ion-injection technique that produces a highly charged dielectric nanolayer, are investigated. It is demonstrated that the field-induced electron layer underneath the dielectric can reach a dark sheet resistance of 0.95 kΩ sq−1 on a 1 Ω cm n-type substrate, lower than any previously reported. In addition, it is shown that the implied open-circuit voltage of a p-type IL cell precursor with a highly charged dielectric is equivalent to that of a cell with a phosphorous emitter. In the cell precursor, light-beam-induced current measurements are performed, and the uniformity and performance of the IL is demonstrated. Finally, simulations are used to explain the physical characteristics of the interface leading to extremely low sheet resistances, and to assess the efficiency potential of IL cells. IL cells are predicted to reach an efficiency of 24.5%, and 24.8% on 5/10 Ω cm substrates, by replacing the phosphorous emitter with a simpler manufacturing process. This requires a charge density of beyond 2 × 1013 cm−2, as is demonstrated here. Moreover, IL cells perform even better at higher charge densities and when negative charge is optimized at the rear dielectric.

Conventional microscale 3D printing techniques mostly rely on the raster scanning method, which needs constant changing of printer head/light beam/substrate directions to print a solid structure. Therefore, throughput is a longstanding bottleneck and it is more challenging to print microfeatures in large areas. This study demonstrates the possibility of 3D printing microfeatures on a fast-spinning disc. A Blu-ray drives based high-throughput 3D printer (BRIGHT3D) is developed to demonstrate the spin printing on disc concept and evaluate the highest linear printing speed. The BRIGHT3D integrates two Blu-ray drives that are synchronized by a customized controller. The printing substrate is a standard Blu-ray RW disc spun by a spindle motor. Both drives utilize the same optical pick-up unit (OPU), which equips a voice coil motor (VCM) for the disc wobbling compensation. The bottom OPU detects the disc wobbling and feeds the VCM control signal back to top OPU for maintaining laser (405 nm, 658 microwatts) focused on the spinning substrate disc. The BRIGHT3D can directly spin-coat (up to 6,440 rpm) commercial photopolymers with a controllable thickness on top of the substrate disc. The top OPU laser was switched with a frequency of 1~500 kHz (duty cycle: 80 %) for the preliminary spinning 3D printing evaluation. Microfeatures can be cured by the BRIGHT3D while the disc is spinning at a speed of 265 rpm, which has a linear speed from inner diameter, 20 mm, to the outer diameter, 58.5 mm, of 0.55~1.63 meters per second. After removing the photopolymer residues by 75% ethanol, various microscale features on the disc can be seen and measured by scanning electron microscopy. Microscale lines (height/width: 1.43/8.25 microns) and dots (length: 5.97 microns) were successfully printed on the disc. The BRIGHT3D is aiming for multiple layer printing on the disc to realize sophisticated features of high-throughput 3D printing in the near future.

Conventional photopolymerization-based 3D printing still requires developing a concise and cost-effective method to improve the printing resolution at the nanoscale. Here, we propose the use of a gaming console optical drive pickup unit for 3D photopolymerization. This mass-produced optical pickup unit features a finely adjustable diode laser, allowing us to adjust the printing resolution from tens of micrometres down to hundreds of nanometres without requiring oxygen radical scavenging or costly femtosecond lasers. We evaluate the 3D printing performance using a commercial photopolymer under different laser exposure parameters. The proposed printing system achieves a resolution of 385 nm along the lateral direction and XYZ nano-resolution linear stages enable a printing volume of up to 50 × 50 × 25 mm3. Finally, we demonstrate the fabrication of 3D stereoscopic microstructures. The substantially simplified optics proposed here paves the way for affordable high-resolution micro/nanoscale 3D fabrication. While 3D printing applications range from aerospace manufacturing to the design of drug delivery systems, current technologies reaching the micro and nanoscale resolution are limited by the complexity and cost of their components. Here, the authors show that nanoscale cost-effective 3D printing can be achieved by using a gaming console optical drive pickup for 3D photopolymerization.

Quantifying molecular surface diffusivity is of broad interest in many different fields of science and technology. In this study, the method of surface grating decay is utilized to investigate the surface diffusion of practical relevant amorphous solid dispersions of indomethacin and the polymeric excipient Soluplus (a polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer) at various polymer concentrations (1-20% w/w). The study confirms that measuring surface diffusivity below the system's glass transition temperature is possible with a simplified atomic force microscopy setup. Results highlight a striking polymer influence on the surface diffusivity of drug molecules at low polymer concentrations and a turnover point to a polymer dominated diffusion at around three percent (w/w) polymer concentration. The surface diffusion measurements further correlate well with the observed increase in physical stability of the system as measured by X-ray powder diffraction. These findings are of vital interest in both the applied use and fundamental understanding of amorphous solid dispersions.

The wide and ever-increasing applications of thermoplasmonics demand the need for sensitive and reliable tools to probe optical absorptions of individual nanoparticles. However, most of the currently available techniques focus only on measuring the surface temperature of nanostructures in a particular medium and are either invasive or suffer from low sensitivity, lengthy calibration, or the inability to probe single structures with nanogaps. Here, we present for the first time the use of micromechanical SiN string resonators for quantifying optical absorption cross sections of individual plasmonic nanostructures. Monomers and dimers of nanospheres, nanostars, shell-isolated nanoparticles, and nanocubes are probed. A reliable data treatment method is developed to obtain the absorption cross sections as a function of responsivity across a string. The presented method exhibits an excellent sensitivity of ∼89 Hz/K. This allows quantification of optical absorption cross sections of individual plasmonic structures even when their plasmon resonance wavelengths are far from the laser excitation wavelength. The experimentally obtained optical absorption cross sections agree well with the simulations. Influencing factors including polarization, surface morphology, and nanogap size are discussed. The developed method and the obtained optical absorption profiles facilitate future development and optimization of thermoplasmonic applications.

The initial formation process of nanobubbles at solid–water interfaces remains unclear because of the limitations of current imaging techniques. To directly observe the formation process, an astigmatic high-speed atomic force microscope (AFM) was modified to enable imaging in the liquid environment. By using a customized cantilever holder, the resonance of small cantilevers was effectively enhanced in water. The proposed high-speed imaging technique yielded highly dynamic quasi-two-dimensional (2D) gas structures (thickness: 20–30 nm) initially at the graphite–water interface. The 2D structures were laterally mobile mainly within certain areas, but occasionally a gas structure might extensively migrate and settle in a new area. The 2D structures were often confined by substrate step edges in one lateral dimension. Eventually, all quasi-2D gas structures were transformed into cap-shaped nanobubbles of higher heights and reduced lateral dimensions. These nanobubbles were immobile and remained stable under continuous AFM imaging. This study demonstrated that nanobubbles could be stably imaged at a scan rate of 100 lines per second (640 μm/s).

Degradable biopolymers are used as carrier materials in drug delivery devices. A complete understanding of their degradation behaviour is thus crucial in the design of new delivery systems. Here we combine a reliable method, based on spray coated micromechanical resonators and a disposable microfluidic chip, to characterize biopolymer degradation under the action of enzymes in controlled flow condition. The sensing platform is based on the mechanics and optics from a Blu-Ray player, which automatically localize individual sensors within the array, and sequentially measure and record the resonance frequency of up to twelve resonators within 4 min. Such fast and automated measuring technology, combined with the use of thin polymers layers in the degradation experiments, allows to reduce the experimental time needed for degradation studies from 6 weeks to 8 h. We first present a full characterization of sensor properties and then perform degradation studies of poly(lactic-co-glycolic acid) (PLGA) in steady flow for three different enzyme concentrations. The degradation has been performed in liquid environment. Before each resonator measurement, the measuring chamber has been automatically dried, since the resonator characteristics are much approved when measuring in air compared to liquid. The obtained degradation profiles are comparable to profiles obtained by conventional approaches, which have shown to require up to 6 weeks of experimental time frame.

Air pollutants have become the major problem of many cities, causing millions of human deaths worldwide every year. Among all the noxious pollutants in air, particles with a diameter of 2.5 micrometers or less (PM2.5) are the most hazardous because they are small enough to penetrate to the lungs and invade the smallest airways. Since the presence of dangerous levels of PM2.5, commonly reported in newspapers and on TV, is intertwined with the global pattern of production and consumption, there is a need for citizen science projects that engage the young generations in efforts toward reducing air pollution as they will become the future leaders of society. With this goal, and to enable the geo-temporal characterization of PM2.5, we present a crowdsourcing-based air pollution measurement system that uses affordable DIY atomic force microscopes to measure and characterize PM2.5, exploiting the power of human computation through an online crowdsourcing platform to study how PM2.5 varies over time and across geographical locations. Our system is intended as both a scientific platform and a teaching tool for children to engage in environmental policy.

This paper describes an aptamer-based optomagnetic biosensor for detection of a small molecule based on target binding-induced inhibition of magnetic nanoparticle (MNP) clustering. For the detection of a target small molecule, two mutually exclusive binding reactions (aptamer-target binding and aptamer-DNA linker hybridization) are designed. An aptamer specific to the target and a DNA linker complementary to a part of the aptamer sequence are immobilized onto separate MNPs. Hybridization of the DNA linker and the aptamer induces formation of MNP clusters. The target-to-aptamer binding on MNPs prior to the addition of linker-functionalized MNPs significantly hinders the hybridization reaction, thus reducing the degree of MNP clustering. The clustering state, which is thus related to the target concentration, is then quantitatively determined by an optomagnetic readout technique that provides the hydrodynamic size distribution of MNPs and their clusters. A commercial Blu-ray optical pickup unit is used for optical signal acquisition, which enables the establishment of a low-cost and miniaturized biosensing platform. Experimental results show that the degree of MNP clustering correlates well with the concentration of a target small molecule, adenosine triphosphate (ATP) in this work, in the range between 10µM and 10mM. This successful proof-of-concept indicates that our optomagnetic aptasensor can be further developed as a low-cost biosensing platform for detection of small molecule biomarkers in an out-of-lab setting.

Thermal analysis plays an important role in both industrial and fundamental research and is widely used to study thermal characteristics of a variety of materials. However, despite considerable effort using different techniques, research struggles to resolve the physico-chemical nature of many thermal transitions such as amorphous relaxations or structural changes in proteins. To overcome the limitations in sensitivity of conventional techniques and to gain new insight into the thermal and mechanical properties of small and large molecule samples, we have developed an instrumental analysis technique using resonating low stress silicon nitride microstrings. With a simple sample deposition method and post process data analysis, we are able to perform rapid thermal analysis of direct instrumental triplicate samples with only pico- to nanograms of material. Utilizing this method, we present the first measurement of amorphous alpha and beta relaxation, as well as liquid crystalline transitions and decomposition of small molecule samples deposited onto a micro string resonator. Furthermore, sensitive measurements of the glass transition of polymers and yet unresolved thermal responses of proteins below their apparent denaturation temperature, which seem to include the true solid state glass transition of pure protein, are reported. Where applicable, thermal events detected with the setup were in good agreement with conventional techniques such as differential scanning calorimetry and dynamic mechanical analysis. The sensitive detection of even subtle thermal transitions highlights further possibilities and applications of resonating microstrings in instrumental physico-chemical analysis.

The optical pickup unit (OPU) within a CD/DVD/Blu-ray drive integrates 780, 650, and 405 nm wavelength lasers, diffraction-limited optics, a high-bandwidth optoelectronic transducer up to 400 MHz, and a nanoresolution x-, z-axis, and tilt actuator in a compact size. In addition, the OPU is a remarkable piece of engineering and could enable different scientific applications such as sub-angstrom displacement sensing, micro- and nanoimaging, and nanolithography. Although off-the-shelf OPUs can be easily obtained, manufacturers protect their datasheets under nondisclosure agreements to impede their availability to the public. Thus, OPUs are black boxes that few people can use for research, and only experienced researchers can access all their functions. This review details the OPU mechanism and components. In addition, we explain how to utilize three commercially available triple-wavelength OPUs from scratch and optimize sensing quality. Then, we discuss scientific research using OPUs, from standard optical drive-based turnkey-biomarker array reading and OPU direct bioapplications (cytometry, optical tweezing, bioimaging) to modified OPU-based biosensing (DNA chip fluorescence scanning, biomolecular diagnostics). We conclude by presenting future trends on optical storage devices and potential applications. Hacking low-cost and high-performance OPUs may spread micro- and nanoscale biosensing research from research laboratories to citizen scientists around the globe.

Astigmatic detection systems have been used in hybrid systems to produce both contact and noncontact profilometers, which provide advantageous features such as low cost, small laser spot, high bandwidth, and compact size. However, current astigmatic optical profilometers cannot provide quantitative height measurement on a surface consisting of complex materials. In this paper, a novel method called z-axis modulation is proposed to overcome this limitation. A homemade astigmatic optical profilometer was developed, and an analytical process for height calculation was also developed. As demonstrated by the experimental results, z-axis modulation can provide accurate height measurement. Furthermore, optical properties such as reflectivity can also be measured.

The mechanism of action (MOA) of the first line type-2 diabetes drug metformin remains unclear despite its widespread usage. However, recent evidence suggests that the mitochondrial copper (Cu)-binding action of metformin may contribute toward the drug’s MOA. Here, we present a novel biosensing platform for investigating the MOA of metformin using a magnetic microbead-based agglutination assay which has allowed us to demonstrate for the first time the interaction between Cu and metformin at clinically relevant low micromolar concentrations of the drug, thus suggesting a potential pathway of metformin’s blood-glucose lowering action. In this assay, cysteine-functionalized magnetic beadswere agglutinated in the presence of Cu due to cysteine’s Cu-chelation property. Addition of clinically relevant doses of metformin resulted in disaggregation of Cu-bridged bead-clusters, whereas the effect of adding a closely related but blood-glucose neutral drug propanediimidamide (PDI) showed completely different responses to the clusters. The entire assay was integrated in an automated microfluidics platform with an advanced optical imaging unit by which we investigated these aggregation–disaggregation phenomena in a reliable, automated, and user-friendly fashion with total assay time of 17 min requiring a sample (metformin/PDI) volume of 30 μL. The marked difference of Cu-binding action between the blood-glucose lowering drug metformin and its inactive analogue PDI thus suggests that metformin’s distinctive Cu-binding properties may be required for its effect on glucose homeostasis. The novel automated platform demonstrating this novel investigation thus holds the potential to be utilized for investigating significant and sensitive molecular interactions via magnetic bead-based agglutination assay.

We have developed a high-sensitivity atomic force microscopy (AFM) mode operated in aqueous environment based on the torsional resonance of the cantilever. It is found that the torsional mode can achieve a good spatial resolution even with a relatively large tip. We have used this mode to image different soft materials in water, including DNA molecules and purple membrane. High-resolution images of purple membrane can be obtained at a relatively low ion concentration under a long-range electrostatic force. Thus the torsional mode allows investigators to probe surface structures and their properties under a wide range of solution conditions.

Toxocarosis is a zoonosis caused by the transmission of the Toxocara canis (T. canis) larvae to humans. Its infectious third-stage larvae can invade the brains of paratenic hosts. The resultant brain damage can result in cerebral toxocarosis (CT). Astrocytes have important neurotrophic and neuroprotective functions in the brain. Substantial studies have shown that astrocyte apoptosis may contribute to the pathogenesis of many acute and chronic neurodegenerative disorders. We propose an alternation detection method, a combination of the astigmatic detection microscopy (ADM) and atomic force microscopy (AFM) techniques, to investigate the apoptosis of astrocytes triggered with T. canis larval excretory/secretory (Tc E/S) antigen. The variation in the pathology of a cell's morphological changes was investigated with ADM and AFM analyses and then confirmed by western blotting. The results showed that the round cells increased as the concentration of Tc E/S antigen and incubated time increased. In addition, the mean height of apoptotic cells was approximately twice that of untreated normal cells, which meant there was correlation between the Tc E/S antigen treatment and cell height. For each cleaved caspase-3 in the cells cocultured with Tc E/S antigen and incubated for 9 h, the corresponding intensities increased about 34-fold (34.4 ± 1.8) compared with those of the control cells. This method can provide researchers with a perspective for understanding the limited information on the mechanism of astroglial injury and death during a T. canis larval invasion in a brain infection.

A plug-and-play CD-like platform is used to perform a statistical detection of platelet derived growth factor (PDGF) proteins through aptamer-based surface functionalization of multiple microcantilever arrays. When PDGF proteins bind to aptamer coatings, the cantilevers deflect. The deflection response is monitored by optical read-out units from a commercial DVD-ROM device. We report on the use of an improved sensing platform which facilitates measurements under continuous liquid flow and with temperature control. Also, the mechanical wobbling of the DVD-ROM platform has been minimized and the scanning system has been optimized in order to detect cantilever deflections in liquid with nanometer scale resolution. The capability of the sensing platform is demonstrated by detection of clinically relevant concentrations of PDGF proteins. We present statistical measurements on 100 microcantilevers at different concentrations of PDGF, ranging from 10 nM to 400 nM. Hereby it is possible to reliably characterize the averaged mechanical response of cantilevers as a function of protein concentration.