Emerging technologies for point-of-care genetic testing

DNA Genotyping Based on Isothermal Amplification and Colorimetric Detection by Consumer Electronics Devices

The point-of-care testing of DNA biomarkers requires compact biosensing systems and consumer electronic technologies provide fascinating opportunities. Their portability, mass-produced components, and high-performance readout capabilities are the main advantages for the development of novel bioanalytical methods.This chapter describes the detection of single nucleotide polymorphisms (SNP) through methods based on user-friendly optical devices (e.g., USB digital microscope, flatbed scanner, smartphone, and DVD drive). Loop mediated isothermal amplification (LAMP) enables the required discrimination of each specific variant prior to the optical reading. In the first method, products are directly hybridized to the allele-specific probes attached to plastic chips in an array format. The second method, allele-specific primers are used, enabling the direct end-point detection based a colorimetric dyer and a microfluidic chamber chip. In both approaches, devices are employed for chip scanning.A representative application to the genotyping of a clinically relevant SNP from human samples is provided, showing the excellent features achieved. Consumer electronic devices are able to register sensitive precise measurements in terms of signal-to-noise ratios, image resolution, and scan-to-scan reproducibility. The integrated DNA-based method lead a low detection limit (100 genomic DNA copies), reproducible (variation <15%), high specificity (genotypes validated by reference method), and cheap assays (<10 €/test). The underlying challenge is the reliable implementation into minimal-specialized clinical laboratories, incorporating additional advantages, such as user-friendly interface, low cost, and connectivity for telemedicine needs.

Computational methods to identify bimodal gene expression and facilitate personalized treatment in cancer patients

Standard methods for detecting cancer-associated genes rely on comparison of sample means between cancer patients and healthy controls. While such methods have successfully identified several oncogenes and tumor suppressor genes, they neglect to account for heterogeneity within the cancer population. Genetic mutations, translocations, and amplifications are often inconsistent across tumors, and instead they often affect smaller subsets of patients. This concept gives rise to the idea of bimodally expressed genes, or genes that display two modes of expression within one population. Analysis of bimodal gene expression has been explored via a variety of techniques including test statistics and clustering. In this review, we summarize the methodologies used to quantify bimodal gene expression and address the utility of these genes in patient stratification and specialized therapeutics in breast and lung cancer. Finally we discuss the limitations and future directions for bimodal genes in the era of high-throughput sequencing and personalized medicine.

Implementing Clinical Pharmacogenomics in the Classroom: Student Pharmacist Impressions of an Educational Intervention Including Personal Genotyping

Pharmacogenomics provides a personalized approach to pharmacotherapy by using genetic information to guide drug dosing and selection. However, partly due to lack of education, pharmacogenomic testing has not been fully implemented in clinical practice. With pharmacotherapy training and patient accessibility, pharmacists are ideally suited to apply pharmacogenomics to patient care. Student pharmacists (n = 222) participated in an educational intervention that included voluntary personal genotyping using 23andMe. Of these, 31% of students completed both pre- and post-educational interventions to evaluate their attitudes and confidence towards the use of pharmacogenomics data in clinical decision making, and 55% of this paired subset obtained personal genotyping. McNemar’s test and the Wilcoxon signed-rank test were used to analyze responses. Following the educational intervention, students regardless of genotyping were more likely to recommend personal genotyping (36% post-educational intervention versus 19% pre-educational intervention, p = 0.0032), more confident in using pharmacogenomics in the management of drug therapy (51% post-educational intervention versus 29% pre-educational intervention, p = 0.0045), and more likely to believe that personalized genomics would have an important role in their future pharmacy career (90% post-educational intervention versus 51% pre-educational intervention, p = 0.0072) compared to before receiving the educational intervention. This educational intervention positively influenced students’ attitudes and confidence regarding pharmacogenomics in the clinical setting. Future studies will examine the use of next-generation sequencing assays that selectively examine pharmacogenes in the education of student pharmacists.

Therapeutic nanomedicine surmounts the limitations of pharmacotherapy

Science always strives to find an improved way of doing things and nanoscience is one such approach. Nanomaterials are suitable for pharmaceutical applications mostly because of their size which facilitates absorption, distribution, metabolism and excretion of the nanoparticles. Whether labile or insoluble nanoparticles, their cytotoxic effect on malignant cells has moved the use of nanomedicine into focus. Since nanomedicine can be described as the science and technology of diagnosing, treating and preventing diseases towards ultimately improving human health, a lot of nanotechnology options have received approval by various regulatory agencies. Nanodrugs also have been discovered to be more precise in targeting the desired site, hence maximizing the therapeutic effects, while minimizing side-effects on the rest of the body. This unique property and more has made nanomedicine popular in therapeutic medicine employing nanotechnology in genetic therapy, drug encapsulation, enzyme manipulation and control, tissue engineering, target drug delivery, pharmacogenomics, stem cell and cloning, and even virus-based hybrids. This review highlights nanoproducts that are in development and have gained approval through one clinical trial stage or the other.

Whole Blood Gene Expression Differentiates between Atrial Fibrillation and Sinus Rhythm after Cardioversion

Background

Treatment to restore sinus rhythm among patients with atrial fibrillation (AF) has limited long-term success rates. Gene expression profiling may provide new insights into AF pathophysiology.

Objective

To identify biomarkers and improve our understanding of AF pathophysiology by comparing whole blood gene expression before and after electrical cardioversion (ECV).

Methods

In 46 patients with persistent AF that underwent ECV, whole blood samples were collected 1–2 hours before and 4 to 6 weeks after successful cardioversion. The paired samples were sent for microarray and plasma biomarker comparison.

Results

Of 13,942 genes tested, expression of SLC25A20 and PDK4 had the strongest associations with AF. Post-cardioversion, SLC25A20 and PDK4 expression decreased by 0.8 (CI 0.7–0.8, p = 2.0x10^-6) and 0.7 (CI 0.6–0.8, p = 3.0x10^-5) fold respectively. Median N-terminal pro B-type natriuretic peptide (NT-proBNP) concentrations decreased from 127.7 pg/mL to 44.9 pg/mL (p = 2.3x10^-13) after cardioversion. AF discrimination models combining NT-proBNP and gene expression (NT-proBNP + SLC25A20 area under the curve = 0.88, NT-proBNP + PDK4 AUC = 0.86) had greater discriminative capacity as compared with NT-proBNP alone (AUC = 0.82). Moreover, a model including NT-proBNP, SLC25A20 and PDK4 significantly improved AF discrimination as compared with other models (AUC = 0.87, Net Reclassification Index >0.56, p<5.8x10^-3). We validated the association between SLC25A20 and PDK4 with AF in an independent sample of 17 patients.

Conclusion

This study demonstrates that SLC25A20, PDK4, and NT-proBNP have incremental utility as biomarkers discriminating AF from sinus rhythm. Elevated SLC25A20 and PDK4 expression during AF indicates an important role for energy metabolism in AF.

Peripheral Blood MCEMP1 Gene Expression as a Biomarker for Stroke Prognosis

BACKGROUND AND PURPOSE

A limitation when making early decisions on stroke management is the lack of rapid diagnostic and prognostic testing. Our study sought to identify peripheral blood RNA biomarkers associated with stroke. The secondary aims were to assess the discriminative capacity of RNA biomarkers for primary stroke type and stroke prognosis at 1-month.

METHODS

Whole-blood gene expression profiling was conducted on the discovery cohort: 129 first-time stroke cases that had blood sampling within 5 days of symptom onset and 170 control participants with no history of stroke.

RESULTS

Through multiple regression analysis, we determined that expression of the gene MCEMP1 had the strongest association with stroke of 11 181 genes tested. MCEMP1 increased by 2.4-fold in stroke when compared with controls (95% confidence interval, 2.0-2.8; P=8.2×10(-22)). In addition, expression was elevated in intracerebral hemorrhage when compared with ischemic stroke cases (P=3.9×10(-4)). MCEMP1 was also highest soon after symptom onset and had no association with stroke risk factors. Furthermore, MCEMP1 expression independently improved discrimination of 1-month outcome. Indeed, discrimination models for disability and mortality that included MCEMP1 expression, baseline modified Rankin Scale score, and primary stroke type improved discrimination when compared with a model without MCEMP1 (disability Net Reclassification Index, 0.76; P=3.0×10(-6) and mortality Net Reclassification Index, 1.3; P=1.1×10(-9)). Significant associations with MCEMP1 were confirmed in an independent validation cohort of 28 stroke cases and 34 controls.

CONCLUSIONS

This study demonstrates that peripheral blood expression of MCEMP1 may have utility for stroke diagnosis and as a prognostic biomarker of stroke outcome at 1-month.

Implementation and utilization of genetic testing in personalized medicine

Clinical genetic testing began over 30 years ago with the availability of mutation detection for sickle cell disease diagnosis. Since then, the field has dramatically transformed to include gene sequencing, high-throughput targeted genotyping, prenatal mutation detection, preimplantation genetic diagnosis, population-based carrier screening, and now genome-wide analyses using microarrays and next-generation sequencing. Despite these significant advances in molecular technologies and testing capabilities, clinical genetics laboratories historically have been centered on mutation detection for Mendelian disorders. However, the ongoing identification of deoxyribonucleic acid (DNA) sequence variants associated with common diseases prompted the availability of testing for personal disease risk estimation, and created commercial opportunities for direct-to-consumer genetic testing companies that assay these variants. This germline genetic risk, in conjunction with other clinical, family, and demographic variables, are the key components of the personalized medicine paradigm, which aims to apply personal genomic and other relevant data into a patient’s clinical assessment to more precisely guide medical management. However, genetic testing for disease risk estimation is an ongoing topic of debate, largely due to inconsistencies in the results, concerns over clinical validity and utility, and the variable mode of delivery when returning genetic results to patients in the absence of traditional counseling. A related class of genetic testing with analogous issues of clinical utility and acceptance is pharmacogenetic testing, which interrogates sequence variants implicated in interindividual drug response variability. Although clinical pharmacogenetic testing has not previously been widely adopted, advances in rapid turnaround time genetic testing technology and the recent implementation of preemptive genotyping programs at selected medical centers suggest that personalized medicine through pharmacogenetics is now a reality. This review aims to summarize the current state of implementing genetic testing for personalized medicine, with an emphasis on clinical pharmacogenetic testing.

Genotype-guided use of oral antithrombotic therapy: a pharmacoeconomic perspective

Pharmacogenomics focuses on tailoring therapy to the individual as opposed to the historical model of fitting the individual to the therapy, and it offers the potential to maximize medication efficacy while reducing adverse events. By its very nature, personalized medicine is conducive to a patient-centered care model. Oral antithrombotics as a class could benefit immensely from this type of approach because an imbalance of safety and efficacy in either direction can yield deadly consequences. Since the current healthcare climate in the USA requires thoughtful allocation of resources, pharmacoeconomic analysis has become critical for all stakeholders, and the adoption of new technologies hinges upon economic impact. This article summarizes the current state of genetics in oral antithrombotic therapy, including clinical relevance as well as cost-effectiveness from a US healthcare system perspective, and provides insight into the future of pharmacogenomics in treating and preventing thromboembolic disorders.

The big picture on nanomedicine: the state of investigational and approved nanomedicine products

Developments in nanomedicine are expected to provide solutions to many of modern medicine's unsolved problems, so it is no surprise that the literature contains many articles discussing the subject. However, existing reviews tend to focus on specific sectors of nanomedicine or to take a very forward-looking stance and fail to provide a complete perspective on the current landscape. This article provides a more comprehensive and contemporary inventory of nanomedicine products. A keyword search of literature, clinical trial registries, and the Web yielded 247 nanomedicine products that are approved or in various stages of clinical study. Specific information on each was gathered, so the overall field could be described based on various dimensions, including FDA classification, approval status, nanoscale size, treated condition, nanostructure, and others. In addition to documenting the many nanomedicine products already in use in humans, this study identifies several interesting trends forecasting the future of nanomedicine.

FROM THE CLINICAL EDITOR

In this one of a kind review, the state of nanomedicine commercialization is discussed, concentrating only on nanomedicine-based developments and products that are either in clinical trials or have already been approved for use.

Gene-Z: a device for point of care genetic testing using a smartphone

By 2012, point of care (POC) testing will constitute roughly one third of the $59 billion in vitro diagnostics market. The ability to carry out multiplexed genetic testing and wireless connectivity are emerging as key attributes of future POC devices. In this study, an inexpensive, user-friendly and compact device (termed Gene-Z) is presented for rapid quantitative detection of multiple genetic markers with high sensitivity and specificity. Using a disposable valve-less polymer microfluidic chip containing four arrays of 15 reaction wells each with dehydrated primers for isothermal amplification, the Gene-Z enables simultaneous analysis of four samples, each for multiple genetic markers in parallel, requiring only a single pipetting step per sample for dispensing. To drastically reduce the cost and size of the real-time detector necessary for quantification, loop-mediated isothermal amplification (LAMP) was performed with a high concentration of SYTO-81, a non-inhibiting fluorescent DNA binding dye. The Gene-Z is operated using an iPod Touch, which also receives data and carries out automated analysis and reporting via a WiFi interface. This study presents data pertaining to performance of the device including sensitivity and reproducibility using genomic DNA from Escherichia coli and Staphylococcus aureus. Overall, the Gene-Z represents a significant step toward truly inexpensive and compact tools for POC genetic testing.

Microfluidic reactors for diagnostics applications

Diagnostic assays are an important part of health care, both in the clinic and in research laboratories. In addition to improving treatments and clinical outcomes, rapid and reliable diagnostics help track disease epidemiology, curb infectious outbreaks, and further the understanding of chronic illness. Disease markers such as antigens, RNA, and DNA are present at low concentrations in biological samples, such that the majority of diagnostic assays rely on an amplification reaction before detection is possible. Ideally, these amplification reactions would be sensitive, specific, inexpensive, rapid, integrated, and automated. Microfluidic technology currently in development offers many advantages over conventional benchtop reactions that help achieve these goals. The small reaction volumes and energy consumption make reactions cheaper and more efficient in a microfluidic reactor. Additionally, the channel architecture could be designed to perform multiple tests or experimental steps on one integrated, automated platform. This review explores the current research on microfluidic reactors designed to aid diagnostic applications, covering a broad spectrum of amplification techniques and designs.

On-chip analysis of respiratory viruses from nasopharyngeal samples

Point-of-care (PoC) testing followed by personalized efficient therapy of infectious diseases may result in a considerable reduction of associated health care costs. Lab-on-a-chip (LoC) systems represent a potentially high efficient class of PoC tools. Here, we present a LoC system for automated pathogen analysis of respiratory viruses from nasopharyngeal specimens. The device prepares total nucleic acids from extracted swab samples using magnetic silica beads. After reverse transcription the co-purified viral RNA is amplified in accordance with the QIAplex multiplex PCR technology. Hybridized to corresponding QIAGEN LiquiChip beads and labelled with streptavidin R-phycoerythrin, the amplified target sequences are finally detected using a QIAGEN LiquiChip200 workstation. All chemicals needed are either stored freeze-dried on the disposable chip or are provided in liquid form in a reagent cartridge for up to 24 runs. Magnetic stir bars for mixing as well as turning valves with metering structures are integrated into the injection-moulded disposable chip. The core of the controlling instrument is a rotating heating bar construction providing fixed temperatures for fast cycling. PCR times of about half an hour (for 30 cycles) could be achieved for 120 μl reactions, making this system the fastest currently available high-volume PCR chip. The functionality of the system was shown by comparing automatically processed nasopharyngeal samples to ones processed manually according to the QIAGEN "ResPlex™ II Panel v2.0" respiratory virus detection kit. A prototype of the present instrument revealed slightly weaker signal intensities with a similar sensitivity in comparison to the commercially available kit and automated nucleic acid preparation devices, even without protocol optimization.

Enrichment of viable bacteria in a micro-volume by free-flow electrophoresis

Macro- to micro-volume concentration of viable bacteria is performed in a microfluidic chip. The enrichment principle is based on free flow electrophoresis and is demonstrated for Gram positive bacteria. Bacteria from a suspension flow are trapped on a gel interface that separates the trapping location from integrated actuation electrodes in order to enable non-destructive trapping. The microfluidic chip contains integrated electrolytic gas expulsion structures and phaseguides for gel and liquid handling. Trapping efficiency is systematically optimized to reach 25 times the initial concentration from a theoretical maximum of 30. Finally, enrichment from analytically relevant concentrations down to 3 × 10(2) colony forming units per millilitre is demonstrated with a trapping efficiency of 80% which represents the most important parameter in enrichment.

Synthesis of tethered poly(N-isopropylacrylamide) for detection of breast cancer recurrence DNA

We have grafted temperature-responsive tethered poly(N-isopropylacrylamide) (PNIPAAm) onto silicon surfaces through atom transfer radical polymerization (ATRP) as a medium to extract human genomic DNA molecules from a biological specimen, namely human blood incorporating target DNA (hgDNA584) and control DNA (hgDNA528) at concentrations of 0.5, 1, and 50 ng μL(-1). The variable adhesion forces of the tethered PNIPAAm brushes on the surfaces were used to capture and release DNA molecules through changes in temperature. After amplifying the signal of the hgDNA584 and hgDNA528 strands released from the tethered PNIPAAm on the substrate using the polymerase chain reaction (PCR), we identified these DNA macromolecules using agarose gel electrophoresis. The accuracy of the detection of hgDNA584 and hgDNA528 was controlled through the design of specific primers in the PCR process. The quantities of these two DNA molecules obtained through the capture and release from tethered PNIPAAm brushes under temperature tuning conditions were sufficient for them to be amplified recognizably, suggesting that this approach could be used in miniaturized lab-on-a-chip cartridges for rapid disease diagnosis.

Genotyping by alkaline dehybridization using graphically encoded particles

This work describes a nonenzymatic, isothermal genotyping method based on the kinetic differences exhibited in the dehybridization of perfectly matched (PM) and single-base mismatched (MM) DNA duplexes in an alkaline solution. Multifunctional encoded hydrogel particles incorporating allele-specific oligonucleotide (ASO) probes in two distinct regions were fabricated by using microfluidic-based stop-flow lithography. Each particle contained two distinct ASO probe sequences differing at a single base position, and thus each particle was capable of simultaneously probing two distinct target alleles. Fluorescently labeled target alleles were annealed to both probe regions of a particle, and the rate of duplex dehybridization was monitored by using fluorescence microscopy. Duplex dehybridization was achieved through an alkaline stimulus using either a pH step function or a temporal pH gradient. When a single target probe sequence was used, the rate of mismatch duplex dehybridization could be discriminated from the rate of perfect match duplex dehybridization. In a more demanding application in which two distinct probe sequences were used, we found that the rate profiles provided a means to discriminate probe dehybridizations from both of the two mismatched duplexes as well as to distinguish at high certainty the dehybridization of the two perfectly matched duplexes. These results demonstrate an ability of alkaline dehybridization to correctly discriminate the rank hierarchy of thermodynamic stability among four sets of perfect match and single-base mismatch duplexes. We further demonstrate that these rate profiles are strongly temperature dependent and illustrate how the sensitivity can be compensated beneficially by the use of an actuating gradient pH field.

Developing a genomic-based point-of-care diagnostic system for rheumatoid arthritis and multiple sclerosis

In this paper the methodology of designing a genomic-based point-of-care diagnostic system composed of a microfluidic Lab-On-Chip, algorithms for microarray image information extraction and knowledge modeling of clinico-genomic patient data is presented. The data are processed by genome wide association studies for two complex diseases: rheumatoid arthritis and multiple sclerosis. Respecting current technological limitations of autonomous molecular-based Lab-On-Chip systems the approach proposed in this work aims to enhance the diagnostic accuracy of the miniaturized LOC system. By providing a decision support system based on the data mining technologies, a robust portable integrated point-of-care diagnostic assay will be implemented. Initially, the gene discovery process is described followed by the detection of the most informative SNPs associated with the diseases. The clinical data and the selected associated SNPs are modeled using data mining techniques to allow the knowledge modeling framework to provide the diagnosis for new patients performing the point-of-care examination. The microfluidic LOC device supplies the diagnostic component of the platform with a set of SNPs associated with the diseases and the ruled-based decision support system combines this genomic information with the clinical data of the patient to outcome the final diagnostic result.

Current status of nanotechnology approaches for cardiovascular disease: a personal perspective

Nanotechnology is poised to have an increasing impact on cardiovascular health in coming years. Diagnostically, multiplexed point-of-care devices will enable rapid genotyping and biomarker measurement to optimize and tailor therapies for the individual patient. Nanoparticle-based molecular imaging agents will take advantage of targeted agents to provide increased insight into disease pathways rather then simply providing structural and functional information. Drug delivery will be impacted by targeting of nanoparticle-encapsulated drugs to the site of action, increasing the effective concentration and decreasing systemic dosage and side effects. Controlled and tailored release of drugs from polymers will improve control of pharmacokinetics and bioavailability. The application of nanotechnology to tissue engineering will facilitate the fabrication of better tissue implants in vitro, and provide scaffolds to promote regeneration in vivo taking advantage of the body's own repair mechanisms. Medical devices will benefit from the development of nanostructured surfaces and coatings to provide better control of thrombogenicity and infection. Taken together, these new technologies have enormous potential for improving the diagnosis and treatment of cardiovascular diseases.

A microfluidic approach for high efficiency extraction of low molecular weight RNA

The lack of sample pre-treatment concepts that are easily automatable, miniaturized and highly efficient for both small volumes and low target concentrations, is one of the key issues that block the road towards effective miniaturized diagnostic instruments. This paper presents a novel, highly efficient and simple method for low-molecular weight RNA extraction using electricity only. Cells are lysed by thermo-electric lysis and RNA is purified using a gel-electrophoretic purification step. The combination of the two steps in one integrated cartridge reduces the time frame between the two steps, thus protecting RNA from enzymatic degradation. A disposable chip solution is proposed using a novel dry film resist laminate technology that allows cheap, large-scale fabrication. The chip contains crucial microfluidic innovations that allow for a simple user interface, reproducible functioning and precise quantification. Phaseguides are invented that allow controlled spatial injection of gel, injection of sample and recovery of extracted RNA. A precise sample volume can be defined by integrating electrophoretic actuation electrodes in the microfluidic chamber. Electrolytic gas bubbles that are the result of constant-current actuation are driven out from the chip by the novel introduction of capillary bubble-expulsion techniques. The extraction approach and the functionality of the chip are demonstrated for Escherichia coli and Streptococcus thermophilus bacteria. Linear extraction behavior is obtained for transfer-messenger RNA down to one colony-forming unit per microlitre, or five colony-forming units per chip. The latter is an increase in extraction efficiency of a factor of 1000 with respect to the commercial extraction kit Ambion Ribopure. The chip shows particularly good performance for extraction of low-molecular weight RNA, thereby eliminating the need for large ribosomal RNA and DNA removal. RNA can be extracted in less than 11 min, being a speed-up of more than a factor of 20 with respect to commercial extraction kits. The presented solution may find broad acceptance and application in drug discovery and clinical diagnostics.

In situ synthesis of DNA microarray on functionalized cyclic olefin copolymer substrate

Thermoplastic materials such as cyclic-olefin copolymers (COC) provide a versatile and cost-effective alternative to the traditional glass or silicon substrate for rapid prototyping and industrial scale fabrication of microdevices. To extend the utility of COC as an effective microarray substrate, we developed a new method that enabled for the first time in situ synthesis of DNA oligonucleotide microarrays on the COC substrate. To achieve high-quality DNA synthesis, a SiO(2) thin film array was prepatterned on the inert and hydrophobic COC surface using RF sputtering technique. The subsequent in situ DNA synthesis was confined to the surface of the prepatterned hydrophilic SiO(2) thin film features by precision delivery of the phosphoramidite chemistry using an inkjet DNA synthesizer. The in situ SiO(2)-COC DNA microarray demonstrated superior quality and stability in hybridization assays and thermal cycling reactions. Furthermore, we demonstrate that pools of high-quality mixed-oligos could be cleaved off the SiO(2)-COC microarrays and used directly for construction of DNA origami nanostructures. It is believed that this method will not only enable synthesis of high-quality and low-cost COC DNA microarrays but also provide a basis for further development of integrated microfluidics microarrays for a broad range of bioanalytical and biofabrication applications.

Emerging optofluidic technologies for point-of-care genetic analysis systems: a review

This review describes recently emerging optical and microfluidic technologies suitable for point-of-care genetic analysis systems. Such systems must rapidly detect hundreds of mutations from biological samples with low DNA concentration. We review optical technologies delivering multiplex sensitivity and compatible with lab-on-chip integration for both tagged and non-tagged optical detection, identifying significant source and detector technology emerging from telecommunications technology. We highlight the potential for improved hybridization efficiency through careful microfluidic design and outline some novel enhancement approaches using target molecule confinement. Optimization of fluidic parameters such as flow rate, channel height and time facilitates enhanced hybridization efficiency and consequently detection performance as compared with conventional assay formats (e.g. microwell plates). We highlight lab-on-chip implementations with integrated microfluidic control for "sample-to-answer" systems where molecular biology protocols to realize detection of target DNA sequences from whole blood are required. We also review relevant technology approaches to optofluidic integration, and highlight the issue of biomolecule compatibility. Key areas in the development of an integrated optofluidic system for DNA hybridization are optical/fluidic integration and the impact on biomolecules immobilized within the system. A wide range of technology platforms have been advanced for detection, quantification and other forms of characterization of a range of biomolecules (e.g. RNA, DNA, protein and whole cell). Owing to the very different requirements for sample preparation, manipulation and detection of the different types of biomolecules, this review is focused primarily on DNA-DNA interactions in the context of point-of-care analysis systems.

Immunoaffinity capillary electrophoresis as a powerful strategy for the quantification of low-abundance biomarkers, drugs, and metabolites in biological matrices

In the last few years, there has been a greater appreciation by the scientific community of how separation science has contributed to the advancement of biomedical research. Despite past contributions in facilitating several biomedical breakthroughs, separation sciences still urgently need the development of improved methods for the separation and detection of biological and chemical substances. In particular, the challenging task of quantifying small molecules and biomolecules, found in low abundance in complex matrices (e.g., serum), is a particular area in need of new high-efficiency techniques. The tandem or on-line coupling of highly selective antibody capture agents with the high-resolving power of CE is being recognized as a powerful analytical tool for the enrichment and quantification of ultra-low abundance analytes in complex matrices. This development will have a significant impact on the identification and characterization of many putative biomarkers and on biomedical research in general. Immunoaffinity CE (IACE) technology is rapidly emerging as the most promising method for the analysis of low-abundance biomarkers; its power comes from a three-step procedure: (i) bioselective adsorption and (ii) subsequent recovery of compounds from an immobilized affinity ligand followed by (iii) separation of the enriched compounds. This technology is highly suited to automation and can be engineered to as a multiplex instrument capable of routinely performing hundreds of assays per day. Furthermore, a significant enhancement in sensitivity can be achieved for the purified and enriched affinity targeted analytes. Thus, a compound that exists in a complex biological matrix at a concentration far below its LOD is easily brought to well within its range of quantification. The present review summarizes several applications of IACE, as well as a chronological description of the improvements made in the fabrication of the analyte concentrator-microreactor device leading to the development of a multidimensional biomarker analyzer.