Ultra-sensitive and multiplex detection of clinical biomarkers using a SPRi-based sensor

Reliable and reproducible biomarker analysis is the main focus of current clinical diagnostic approaches being developed for the sensitive detection and quantification of biomarkers in bodily fluids. Currently used tools are being revised for better analytical performance that overcomes the drawbacks of inaccurate results. Surface plasmon resonance imaging is rising quickly as an affinity-based optical biosensor that demonstrates numerous improvements to the sensor surface design and sensitivity for label-free and real-time biomarker analysis. In this work, our goal is to develop a more sensitive analytical method for the enhanced detection of the human growth hormone (hGH) in serum, multiplex detection of disease biomarkers (KIM-1 and HMGB-1) simultaneously in buffer using a sandwich-amplification assay, and small molecule- progesterone sensing using a novel aptasensor. Our goals were met by ensuring a homogenous and specific immunosensor for detecting hGH at very low concentrations (> 9.1 pg/mL), substituting random antibody attachment with a site directed immobilization to the sensor surface for multiplex detection of two disease biomarkers down to 5 pg/mL levels in buffer, and further increasing the sensitivity of progesterone biosensor by exploiting x-aptamer technology for highly selective detection of progesterone (> 1 nM) in buffer

Surface plasmon resonance: a versatile technique for biosensor applications

Surface plasmon resonance (SPR) is a label-free detection method which has emerged during the last two decades as a suitable and reliable platform in clinical analysis for biomolecular interactions. The technique makes it possible to measure interactions in real-time with high sensitivity and without the need of labels. This review article discusses a wide range of applications in optical-based sensors using either surface plasmon resonance (SPR) or surface plasmon resonance imaging (SPRI). Here we summarize the principles, provide examples, and illustrate the utility of SPR and SPRI through example applications from the biomedical, proteomics, genomics and bioengineering fields. In addition, SPR signal amplification strategies and surface functionalization are covered in the review.open1

Non-Invasive Breast Cancer Diagnosis through Electrochemical Biosensing at Different Molecular Levels

The rapid and accurate determination of specific circulating biomarkers at different molecular levels with non- or minimally invasive methods constitutes a major challenge to improve the breast cancer outcomes and life quality of patients. In this field, electrochemical biosensors have demonstrated to be promising alternatives against more complex conventional strategies to perform fast, accurate and on-site determination of circulating biomarkers at low concentrations in minimally treated body fluids. In this article, after discussing briefly the relevance and current challenges associated with the determination of breast cancer circulating biomarkers, an updated overview of the electrochemical affinity biosensing strategies emerged in the last 5 years for this purpose is provided highlighting the great potentiality of these methodologies. After critically discussing the most interesting features of the electrochemical strategies reported so far for the single or multiplexed determination of such biomarkers with demonstrated applicability in liquid biopsy analysis, existing challenges still to be addressed and future directions in this field will be pointed out

Fast screening for diagnostic of heart ischemic episodes

Dissertação para obtenção do Grau de Doutor em Química SustentávelCardiovascular diseases (CVD) are top-killer chronic diseases, accounting for al-most half of the European deaths in 2010 (Eurostat data). Most recent statistics in Portuguese territory confirm this scenario, with cardiovascular diseases killing about 11 persons per 100000 inhabitants. Reducing these numbers is urgent and requires early, quick and efficient diagnostic of the specific heart condition. Thus, the main goal of this proposal is to develop a low cost sensing-devices based on newly synthesized sensory biomaterials for screening cardiac bi-omarkers in point-of-care. These were applied to screen the conventional bi-omarkers of clinical interest, all peptides in nature. These include troponin T (TnT), creatine kinase isoenzyme (CK-MB) and myoglobin (Myo). This was achieved by means of novel and low cost biosensing materials that were designed to display good selectivity to each biomarker, assembled on nanostructured sens-ing units and tested on serum samples. The design of novel biosensing materials consisted on synthesizing plastic antibodies by means of novel molecular im-printing (MI) and enzymatic approaches. Nanostructured sensing units were as-sembled by modifying the surface of standard conductive materials with the pre-viously indicated biomaterials. Standard conductive supports selected for this purpose were carbon and gold. Overall, it is expected that the emerging biosensing materials and platforms out coming from this project may contribute for the development of new non-inva-sive or minimally invasive methods with clinical application in the early screen-ing of chronic diseases and fast-screening in point-of-care (POC) of acute events

Improving the early diagnostic of prostate cancer by multiple biomarker detection with new biosensing devices

Prostate cancer (PCa) is the most common form of cancer in men, in Europe (World Health Organization data). The most recent statistics, in Portuguese territory, confirm this scenario, which states that about 50% of Portuguese men may suffer from prostate cancer and 15% of these will die from this condition. Its early detection is therefore fundamental. This is currently being done by Prostate Specific Antigen (PSA) screening in urine but false positive and negative results are quite often obtained and many patients are sent to unnecessary biopsy procedures. This early detection protocol may be improved, by the development of point-of-care cancer detection devices, not only to PSA but also to other biomarkers recently identified. Thus, the present work aims to screen several biomarkers in cultured human prostate cell lines, serum and urine samples, developing low cost sensors based on new synthetic biomaterials. Biomarkers considered in this study are the following: prostate specific antigen (PSA), annexin A3 (ANXA3), microseminoprotein-beta (MSMB) and sarcosine (SAR). The biomarker recognition may occurs by means of molecularly imprinted polymers (MIP), which are a kind of plastic antibodies, and enzymatic approaches. The growth of a rigid polymer, chemically stable, using the biomarker as a template allows the synthesis of the plastic antibody. MIPs show high sensitivity/selectivity and present much longer stability and much lower price than natural antibodies. This nanostructured material was prepared on a carbon solid. The interaction between the biomarker and the sensing-material produces electrical signals generating quantitative or semi-quantitative data. These devices allow inexpensive and portable detection in point-of-care testing

Advances in nanoplasmonic biosensors for clinical applications

Biomarkers are unquestionable biological indicators for diagnosis and therapeutic interventions providing appropriate classification of a wide range of health disorders and risk factors. Nonetheless, detection and quantification of biomarkers need to be tested with sufficient reliability by robust analytical methods in order to assure clinical performance in health care settings. Since the analytical performance is determined by the sensitivity and specificity of the method employed, techniques have been intensively refined in order to avoid misinterpretation of results and undesirable bias. Although biomarkers can be detected with the existing analytical techniques, to reproducibly quantify them in decentralized settings or remote locations with the required accuracy is still a challenge. Currently, only a few point-of-care devices for biomarkers evaluation are commercially available. Thus, more focused research efforts are needed to overcome those limitations in order to provide universal patient-centered care platforms. To this end, plasmonic biosensors can be conveniently used as portable diagnostic devices for attaining timely and cost-effective clinical outcomes. The development of enhanced performances based on nanoplasmonics technology opens the way for sensor miniaturization, multiplexing and point of care testing. This review covers recent advances and applications of plasmonic and nanoplasmonic biosensors intended for biomarker diagnosis in the clinical practice, including cancer, cardiovascular and neurodegenerative diseases. The review specially focuses on: (i) recent progress in plasmonics developments including the design of singular nanostructured surfaces, (ii) novel chemical functionalization strategies for the appropriate incorporation of the bioreceptors and (iii) plasmonic applications as real operative devices in the clinical field. Future prospects in the use of nanoplasmonic sensor platforms for personalised quantification and management of biomarkers directly in body fluids will also be discussed.SIICN2 is supported by the Severo Ochoa program from Spanish MINECO (Grant No. SEV-2013- 0295) and EPISENS project (TEC2012-34280)

Aptasensors versus immunosensors—Which will prevail?

Since the invention of the first biosensors 70 years ago, they have turned into valuable and versatile tools for various applications, ranging from disease diagnosis to environmental monitoring. Traditionally, antibodies have been employed as the capture probes in most biosensors, owing to their innate ability to bind their target with high affinity and specificity, and are still considered as the gold standard. Yet, the resulting immunosensors often suffer from considerable limitations, which are mainly ascribed to the antibody size, conjugation chemistry, stability, and costs. Over the past decade, aptamers have emerged as promising alternative capture probes presenting some advantages over existing constraints of immunosensors, as well as new biosensing concepts. Herein, we review the employment of antibodies and aptamers as capture probes in biosensing platforms, addressing the main aspects of biosensor design and mechanism. We also aim to compare both capture probe classes from theoretical and experimental perspectives. Yet, we highlight that such comparisons are not straightforward, and these two families of capture probes should not be necessarily perceived as competing but rather as complementary. We, thus, elaborate on their combined use in hybrid biosensing schemes benefiting from the advantages of each biorecognition element

A Road Map toward Field-Effect Transistor Biosensor Technology for Early Stage Cancer Detection

Field effect transistor (FET)-based nanoelectronic biosensor devices provide a viable route for specific and sensitive detection of cancer biomarkers, which can be used for early stage cancer detection, monitoring the progress of the disease, and evaluating the effectiveness of therapies. On the road to implementation of FET-based devices in cancer diagnostics, several key issues need to be addressed: sensitivity, selectivity, operational conditions, anti-interference, reusability, reproducibility, disposability, large-scale production, and economic viability. To address these well-known issues, significant research efforts have been made recently. An overview of these efforts is provided here, highlighting the approaches and strategies presently engaged at each developmental stage, from the design and fabrication of devices to performance evaluation and data analysis. Specifically, this review discusses the multistep fabrication of FETs, choice of bioreceptors for relevant biomarkers, operational conditions, measurement configuration, and outlines strategies to improve the sensing performance and reach the level required for clinical applications. Finally, this review outlines the expected progress to the future generation of FET-based diagnostic devices and discusses their potential for detection of cancer biomarkers as well as biomarkers of other noncommunicable and communicable diseases