Moving diagnostics from the bench to the bedside

Laser-assisted protein micropatterning in a thermoplastic device for multiplexed prostate cancer biomarker detection

Immunoassays are frequently used for analysis of protein biomarkers. The specificity of antibodies enables parallel analysis of several target proteins, at the same time. However, the implementation of such multiplexed assays into cost-efficient and mass-producible thermoplastic microfluidic platforms remains difficult due to the lack of suitable immobilization strategies for different capture antibodies. Here, we introduce and characterize a method to functionalize the surfaces of microfluidic devices manufactured in the thermoplastic material cyclic olefin copolymer (COC) by a rapid prototyping process. A laser-induced immobilization process enables the surface patterning of anchor biomolecules at a spatial resolution of 5 μm. We employ the method for the analysis of prostate cancer associated biomarkers by competitive immunoassays in a microchannel with a total volume of 320 nL, and successfully detected the proteins PSA, CRP, CEA and IGF-1 at clinically relevant concentrations. Finally, we also demonstrate the simultaneous analysis of three markers spiked into undiluted human plasma. In conclusion, this method opens the way to transfer multiplexed immunoassays into mass-producible microfluidic platforms that are suitable for point of care applications.

Biosensing with Paper-Based Miniaturized Printed Electrodes-A Modern Trend

From the bench-mark work on microfluidics from the Whitesides’s group in 2007, paper technology has experienced significant growth, particularly regarding applications in biomedical research and clinical diagnostics. Besides the structural properties supporting microfluidics, other advantageous features of paper materials, including their versatility, disposability and low cost, show off the great potential for the development of advanced and eco-friendly analytical tools. Consequently, paper was quickly employed in the field of electrochemical sensors, being an ideal material for producing custom, tailored and miniaturized devices. Stencil-, inkjet-, or screen-printing are the preferential techniques for electrode manufacturing. Not surprisingly, we witnessed a rapid increase in the number of publications on paper based screen-printed sensors at the turn of the past decade. Among the sensing strategies, various biosensors, coupling electrochemical detectors with biomolecules, have been proposed. This work provides a critical review and a discussion on the future progress of paper technology in the context of miniaturized printed electrochemical biosensors.

Designed miniaturization of microfluidic biosensor platforms using the stop-flow technique

Here, we present a novel approach to increase the degree of miniaturization as well as the sensitivity of biosensor platforms by the optimization of microfluidic stop-flow techniques independent of the applied detection technique (e.g. electrochemical or optical).

Technology modules from micro- and nano-electronics for the life sciences

The capabilities of modern semiconductor manufacturing offer remarkable possibilities to be applied in life science research as well as for its commercialization. In this review, the technology modules available in micro- and nano-electronics are exemplarily presented for the case of 250 and 130 nm technology nodes. Preparation procedures and the different transistor types as available in complementary metal-oxide-silicon devices (CMOS) and BipolarCMOS (BiCMOS) technologies are introduced as key elements of comprehensive chip architectures. Techniques for circuit design and the elements of completely integrated bioelectronics systems are outlined. The possibility for life scientists to make use of these technology modules for their research and development projects via so-called multi-project wafer services is emphasized. Various examples from diverse fields such as (1) immobilization of biomolecules and cells on semiconductor surfaces, (2) biosensors operating by different principles such as affinity viscosimetry, impedance spectroscopy, and dielectrophoresis, (3) complete systems for human body implants and monitors for bioreactors, and (4) the combination of microelectronics with microfluidics either by chip-in-polymer integration as well as Si-based microfluidics are demonstrated from joint developments with partners from biotechnology and medicine. WIREs Nanomed Nanobiotechnol 2016, 8:355-377. doi: 10.1002/wnan.1367 For further resources related to this article, please visit the WIREs website.

Subtyping clinical specimens of influenza A virus by use of a simple method to amplify RNA targets

This work presents the clinical application of a robust and unique approach for RNA amplification, called a simple method for amplifying RNA targets (SMART), for the detection and identification of subtypes of H1N1 pandemic, H1N1 seasonal, and H3N2 seasonal influenza virus. While all the existing amplification techniques rely on the diffusion of two molecules to complex RNA structures, the SMART achieves fast and efficient amplification via single-molecule diffusion. The SMART utilizes amplifiable single-stranded DNA (ssDNA) probes, which serve as reporter molecules for capturing specific viral RNA (vRNA) sequences and are subsequently separated on a microfluidic chip under zero-flow conditions. The probe amplification and detection are performed using an isothermal (41°C) amplification scheme via a modified version of nucleic acid sequence-based amplification (NASBA). In our study, 116 consecutive, deidentified, clinical nasopharyngeal swab samples were analyzed independently in a blinded fashion using the SMART, reverse transcription-PCR (RT-PCR), antigen (Ag) testing, and viral culture. The SMART was shown to have a limit of detection (LOD) of approximately 10(5) vRNA copies/ml, corresponding with a time-to-positivity (TTP) value of 70 min for real-time detection. The SMART correctly detected influenza virus in 98.3% of the samples with a subtyping accuracy of 95.7%. This work demonstrates that the SMART represents a highly accurate diagnostic platform for the detection and subtyping of influenza virus in clinical specimens and offers significant advantages over the current commercially available diagnostic tools.

CMOS cell sensors for point-of-care diagnostics

The burden of health-care related services in a global era with continuously increasing population and inefficient dissipation of the resources requires effective solutions. From this perspective, point-of-care diagnostics is a demanded field in clinics. It is also necessary both for prompt diagnosis and for providing health services evenly throughout the population, including the rural districts. The requirements can only be fulfilled by technologies whose productivity has already been proven, such as complementary metal-oxide-semiconductors (CMOS). CMOS-based products can enable clinical tests in a fast, simple, safe, and reliable manner, with improved sensitivities. Portability due to diminished sensor dimensions and compactness of the test set-ups, along with low sample and power consumption, is another vital feature. CMOS-based sensors for cell studies have the potential to become essential counterparts of point-of-care diagnostics technologies. Hence, this review attempts to inform on the sensors fabricated with CMOS technology for point-of-care diagnostic studies, with a focus on CMOS image sensors and capacitance sensors for cell studies.

Optical imaging techniques for the study of malaria

Malarial infection needs to be imaged to reveal the mechanisms behind malaria pathophysiology and to provide insights to aid in the diagnosis of the disease. Recent advances in optical imaging methods are now being transferred from physics laboratories to the biological field, revolutionizing how we study malaria. To provide insight into how these imaging techniques can improve the study and treatment of malaria, we summarize recent progress on optical imaging techniques, ranging from in vitro visualization of the disease progression of malaria infected red blood cells (iRBCs) to in vivo imaging of malaria parasites in the liver.

Genetic analysis of H1N1 influenza virus from throat swab samples in a microfluidic system for point-of-care diagnostics

The ability to obtain sequence-specific genetic information about rare target organisms directly from complex biological samples at the point-of-care would transform many areas of biotechnology. Microfluidics technology offers compelling tools for integrating multiple biochemical processes in a single device, but despite significant progress, only limited examples have shown specific, genetic analysis of clinical samples within the context of a fully integrated, portable platform. Herein we present the Magnetic Integrated Microfluidic Electrochemical Detector (MIMED) that integrates sample preparation and electrochemical sensors in a monolithic disposable device to detect RNA-based virus directly from throat swab samples. By combining immunomagnetic target capture, concentration, and purification, reverse-transcriptase polymerase chain reaction (RT-PCR) and single-stranded DNA (ssDNA) generation in the sample preparation chamber, as well as sequence-specific electrochemical DNA detection in the electrochemical cell, we demonstrate the detection of influenza H1N1 in throat swab samples at loads as low as 10 TCID(50), 4 orders of magnitude below the clinical titer for this virus. Given the availability of affinity reagents for a broad range of pathogens, our system offers a general approach for multitarget diagnostics at the point-of-care.

nanoLAB: an ultraportable, handheld diagnostic laboratory for global health

Driven by scientific progress and economic stimulus, medical diagnostics will move to a stage in which straightforward medical diagnoses are independent of physician visits and large centralized laboratories. The future of basic diagnostic medicine will lie in the hands of private individuals. We have taken significant strides towards achieving this goal by developing an autoassembly assay for disease biomarker detection which obviates the need for washing steps and is run on a handheld sensing platform. By coupling magnetic nanotechnology with an array of magnetically responsive nanosensors, we demonstrate a rapid, multiplex immunoassay that eliminates the need for trained technicians to run molecular diagnostic tests. Furthermore, the platform is battery-powered and ultraportable, allowing the assay to be run anywhere in the world by any individual.

Microstructuring of polymer films for sensitive genotyping by real-time PCR on a centrifugal microfluidic platform

We present a novel process flow enabling prototyping of microfluidic cartridges made out of polymer films. Its high performance is proven by implementation of a microfluidic genotyping assay testing 22 DNA samples including clinical isolates from patients infected by methicilin-resistant Staphylococcus aureus (MRSA). The microfluidic cartridges (disks) are fabricated by a novel process called microthermoforming by soft lithography (microTSL). Positive moulds are applied allowing for higher moulding precision and very easy demoulding when compared to conventional microthermoforming. High replication accuracies with geometric disk-to-disk variations of less than 1% are typical. We describe and characterise fabrication and application of microfluidic cartridges with wall thicknesses <188 microm thus enabling efficient thermocycling during real-time polymerase chain reaction (PCR). The microfluidic cartridges are designed for operation in a slightly modified commercial thermocycling instrument. This approach demonstrates new opportunities for both microfluidic developments and well-established laboratory instruments. The microfluidic protocol is controlled by centrifugal forces and divides the liquid sample parallely into independent aliquots of 9.8 microl (CV 3.4%, N = 32 wells). The genotyping assays are performed with pre-stored primers and probes for real-time PCR showing a limit of detection well below 10 copies of DNA per reaction well (N = 24 wells in 3 independent disks). The system was evaluated by 44 genotyping assays comprising 22 DNA samples plus duplicates in a total of 11 disks. The samples contained clinical samples of seven different genotypes of MRSA as well as positive and negative controls. The results are in excellent agreement with the reference in microtubes.

HIV diagnostics: challenges and opportunities

Accurate HIV diagnostic testing continues to pose challenges, but there are also opportunities for assay performance improvements in key areas for specific intended-use settings. The genetic diversity of HIV can result in false and discordant results in assays that fail to detect new variant strains. The use of antiretroviral therapies has resulted in drug-resistant variants that require monitoring by sequencing and genotyping methods. Nucleic acid testing is the most sensitive and reliable platform for detection, but it is costly and limited to centralized testing facilities, making implementation difficult in resource-limited settings where HIV has hit the hardest. Rapid antibody tests suitable for point-of-care use are becoming more accessible in resource-limited settings, but these tests may not detect HIV during the acute infection stage. Emerging antigen/antibody combination assays are viable alternatives to nucleic acid testing for diagnosis of recent infections. Although patient monitoring (e.g., via CD4+ T-cell count and viral load determination) and infant diagnoses still rely on clinical laboratory-based testing, point-of-care options are being developed. There are other technical challenges to HIV diagnostic testing and emerging biodetection technologies that may be able to address them, but they are not yet proven.

Lab-on-a-Foil: microfluidics on thin and flexible films

This critical review is motivated by an increasing interest of the microfluidics community in developing complete Lab-on-a-Chip solutions based on thin and flexible films (Lab-on-a-Foil). Those implementations benefit from a broad range of fabrication methods that are partly adopted from well-established macroscale processes or are completely new and promising. In addition, thin and flexible foils enable various features like low thermal resistance for efficient thermocycling or integration of easily deformable chambers paving the way for new means of on-chip reagent storage or fluid transport. From an economical perspective, Lab-on-a-Foil systems are characterised by low material consumption and often low-cost materials which are attractive for cost-effective high-volume fabrication of self-contained disposable chips. The first part of this review focuses on available materials, fabrication processes and approaches for integration of microfluidic functions including liquid control and transport as well as storage and release of reagents. In the second part, an analysis of the state of Lab-on-a-Foil applications is provided with a special focus on nucleic acid analysis, immunoassays, cell-based assays and home care testing. We conclude that the Lab-on-a-Foil approach is very versatile and significantly expands the toolbox for the development of Lab-on-a-Chip solutions.

A CMOS Time-Resolved Fluorescence Lifetime Analysis Micro-System

We describe a CMOS-based micro-system for time-resolved fluorescence lifetime analysis. It comprises a 16 × 4 array of single-photon avalanche diodes (SPADs) fabricated in 0.35 μm high-voltage CMOS technology with in-pixel time-gated photon counting circuitry and a second device incorporating an 8 × 8 AlInGaN blue micro-pixellated light-emitting diode (micro-LED) array bump-bonded to an equivalent array of LED drivers realized in a standard low-voltage 0.35 μm CMOS technology, capable of producing excitation pulses with a width of 777 ps (FWHM). This system replaces instrumentation based on lasers, photomultiplier tubes, bulk optics and discrete electronics with a PC-based micro-system. Demonstrator lifetime measurements of colloidal quantum dot and Rhodamine samples are presented.

Developing a microfluidic-based system to quantify cell capture efficiency

Micro-fabrication technology has substantial potential for identifying molecular markers expressed on the surfaces of tissue cells and viruses. It has been found in several conceptual prototypes that cells with such markers are able to be captured by their antibodies immobilized on microchannel substrates and unbound cells are flushed out by a driven flow. The feasibility and reliability of such a microfluidic-based assay, however, remains to be further tested. In the current work, we developed a microfluidic-based system consisting of a microfluidic chip, an image grabbing unit, data acquisition and analysis software, as well as a supporting base. Specific binding of CD59-expressed or BSA-coupled human red blood cells (RBCs) to anti-CD59 or anti-BSA antibody-immobilized chip surfaces was quantified by capture efficiency and by the fraction of bound cells. Impacts of respective flow rate, cell concentration, antibody concentration and site density were tested systematically. The measured data indicated that the assay was robust. The robustness was further confirmed by capture efficiencies measured from an independent ELISA-based cell binding assay. These results demonstrated that the system developed provided a new platform to effectively quantify cellular surface markers effectively, which promoted the potential applications in both biological studies and clinical diagnoses.

Electrical protein detection in cell lysates using high-density peptide-aptamer microarrays

BACKGROUND

The dissection of biological pathways and of the molecular basis of disease requires devices to analyze simultaneously a staggering number of protein isoforms in a given cell under given conditions. Such devices face significant challenges, including the identification of probe molecules specific for each protein isoform, protein immobilization techniques with micrometer or submicrometer resolution, and the development of a sensing mechanism capable of very high-density, highly multiplexed detection.

RESULTS

We present a novel strategy that offers practical solutions to these challenges, featuring peptide aptamers as artificial protein detectors arrayed on gold electrodes with feature sizes one order of magnitude smaller than existing formats. We describe a method to immobilize specific peptide aptamers on individual electrodes at the micrometer scale, together with a robust and label-free electronic sensing system. As a proving proof of principle experiment, we demonstrate the specific recognition of cyclin-dependent protein kinases in whole-cell lysates using arrays of ten electrodes functionalized with individual peptide aptamers, with no measurable cross-talk between electrodes. The sensitivity is within the clinically relevant range and can detect proteins against the high, whole-cell lysate background.

CONCLUSION

The use of peptide aptamers selected in vivo to recognize specific protein isoforms, the ability to functionalize each microelectrode individually, the electronic nature and scalability of the label-free detection and the scalability of the array fabrication combine to yield the potential for highly multiplexed devices with increasingly small detection areas and higher sensitivities that may ultimately allow the simultaneous monitoring of tens or hundreds of thousands of protein isoforms.

Aurora kinases and their inhibitors: more than one target and one drug

Dependent on the degree of inhibition of different Aurora kinase family members, various events in mitosis are affected, resulting in differential cellular responses. These different cellular responses have to be considered in the clinical development of the small molecule inhibitors with respect to the chosen indications, schedules and appropriate endpoints. Here the properties of the most advanced small molecule Aurora kinase inhibitors are compared and a case report on the development of PHA-739358 - a spectrum selective kinases inhibitor with a dominant phenotype of Aurora kinases inhibition, which is currently being tested in clinical trials - is discussed. One of the selection criteria for this compound was its property of inhibiting more than one cancer relevant target, such as Abl wild-type and the multidrug resistant Abl T315I mutant. This opens another path for clinical development in CML, and clinical trials are underway to evaluate the activity in patients suffering from chronic myelogenous leukemia, who developed resistance to currently approved treatments.

Nanotechnology in the diagnosis and management of heart, lung and blood diseases

Heart, lung and blood diseases exert an enormous toll, accounting for almost half of the deaths in the USA each year. In addition to the morbidity and mortality resulting from these diseases, there is also a high economic burden, estimated at 560 billion US dollars for 2006. Nanotechnology offers a broad range of opportunities to improve diagnosis and therapy for cardiovascular, pulmonary and hematopoietic diseases, thereby decreasing these burdens. This review will focus on four areas of particular promise for the application of nanotechnology: imaging, diagnostics and biosensors, drug delivery and therapy, and tissue engineering and repair. The goal is to summarize the current state of science and technology in these areas and to look at future directions that the field is likely to move in to enhance the diagnosis and treatment of heart, lung and blood diseases.

A handheld device for potential point-of-care screening of cancer

A simple handheld device based on the fluorescence analysis of 3,6-bis(1-methyl-4-vinylpyridinium)carbazole diiodide (BMVC) stained cells was established for routine screening and potentially for early detection of cancer cells at extremely low cost. Flow cytometry assay further supported the utility of this simple device, where a preliminary study of tissue biopsy showed highly encouraging results.