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  • 1.
    Abellan-Flos, Marta
    et al.
    Univ Namur, Dept Chim, Lab Chim Bioorgan, Rue Bruxelles 61, B-5000 Namur, Belgium.;PSL Univ, CNRS, ESPCI Paris, Mol Macromol Chem & Mat, 10 Rue Vauquelin, F-75005 Paris, France..
    Timmer, Brian J. J.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Altun, Samuel
    Attana AB, Bjornnasvagen 21, S-11419 Stockholm, Sweden..
    Aastrup, Teodor
    Attana AB, Bjornnasvagen 21, S-11419 Stockholm, Sweden..
    Vincent, Stephane P.
    Univ Namur, Dept Chim, Lab Chim Bioorgan, Rue Bruxelles 61, B-5000 Namur, Belgium..
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. Univ Massachusetts, Dept Chem, One Univ Ave, Lowell, MA 01854 USA.;Linnaeus Univ, Dept Chem & Biomed Sci, SE-39182 Kalmar, Sweden..
    QCM sensing of multivalent interactions between lectins and well-defined glycosylated nanoplatforms2019In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 139, article id 111328Article in journal (Refereed)
    Abstract [en]

    Quartz crystal microbalance (QCM) methodology has been adopted to unravel important factors contributing to the "cluster glycoside effect" observed in carbohydrate-lectin interactions. Well-defined, glycosylated nanostructures of precise sizes, geometries and functionalization patterns were designed and synthesized, and applied to analysis of the interaction kinetics and thermodynamics with immobilized lectins. The nanostructures were based on Borromean rings, dodecaamine cages, and fullerenes, each of which carrying a defined number of carbohydrate ligands at precise locations. The synthesis of the Borromeates and dodecaamine cages was easily adjustable due to the modular assembly of the structures, resulting in variations in presentation mode. The binding properties of the glycosylated nanoplatforms were evaluated using flow-through QCM technology, as well as hemagglutination inhibition assays, and compared with dodecaglycosylated fullerenes and a monovalent reference. With the QCM setup, the association and dissociation rate constants and the associated equilibrium constants of the interactions could be estimated, and the results used to delineate the multivalency effects of the lectin-nanostructure interactions.

  • 2. Afshar, Majid Ghahraman
    et al.
    Crespo, Gaston A.
    Bakker, Eric
    Counter electrode based on an ion-exchanger Donnan exclusion membrane for bioelectroanalysis2014In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 61, p. 64-69Article in journal (Refereed)
  • 3. Ampurdanes, Jordi
    et al.
    Crespo, Gaston A.
    Maroto, Alicia
    Angeles Sarmentero, M.
    Ballester, Pablo
    Xavier Rius, F.
    Determination of choline and derivatives with a solid-contact ion-selective electrode based on octaamide cavitand and carbon nanotubes2009In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 25, no 2, p. 344-349Article in journal (Refereed)
  • 4. Ashaduzzaman, M.
    et al.
    Anto Antony, A.
    Arul Murugan, Natarajan
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Deshpande, S. R.
    Turner, A. P. F.
    Tiwari, A.
    Studies on an on/off-switchable immunosensor for troponin T2015In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 73Article in journal (Refereed)
    Abstract [en]

    Regeneration is a key goal in the design of immunosensors. In this study, we report the temperature-regulated interaction of N-isopropylacrylamide (PNIPAAm) functionalised cardiac troponin T (cTnT) with anti-cTnT. Covalently bonded PNIPAAm on an anti-cTnT bioelectrode showed on/off-switchability, regeneration capacity and temperature triggered sensitivity for cTnT. Above the lower critical solution temperature (LCST), PNIPAAm provides a liphophilic microenvironment with specific volume reduction at the bioelectrode surface, making available binding space for cTnT, and facilitating analyte recognition. Computational studies provide details about the structural changes occurring at the electrode above and below the LCST. Furthermore, free energies associated with the binding of cTnT with PNIPAAm at 25 (δG<inf>coil</inf>=-6.0Kcal/mole) and 37°C (δG<inf>globular</inf>=-41.0kcal/mole) were calculated to elucidate the interaction and stability of the antigen-antibody complex. The responsiveness of such assemblies opens the way for miniaturised, smart immuno-technologies with 'built-in' programmable interactions of antigen-antibody upon receiving stimuli.

  • 5.
    Cánovas, Rocío
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Cuartero, Maria
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Crespo, Gaston A.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Modern creatinine (Bio)sensing: Challenges of point-of-care platforms2019In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 130, p. 110-124Article, review/survey (Refereed)
    Abstract [en]

    The importance of knowing creatinine levels in the human body is related to the possible association with renal, muscular and thyroid dysfunction. Thus, the accurate detection of creatinine may indirectly provide information surrounding those functional processes, therefore contributing to the management of the health status of the individual and early diagnosis of acute diseases. The questions at this point are: to what extent is creatinine information clinically relevant?; and do modern creatinine (bio)sensing strategies fulfil the real needs of healthcare applications? The present review addresses these questions by means of a deep analysis of the creatinine sensors reported in the literature over the last five years. There is a wide range of techniques for detecting creatinine, most of them based on optical readouts (20 of the 33 papers collected in this review). However, the use of electrochemical techniques (13 of the 33 papers) is recently emerging in alignment with the search for a definitive and trustworthy creatinine detection at the point-of-care level. In this sense, biosensors (7 of the 33 papers) are being established as the most promising alternative over the years. While creatinine levels in the blood seem to provide better information about patient status, none of the reported sensors display adequate selectivity in such a complex matrix. In contrast, the analysis of other types of biological samples (e.g., saliva and urine) seems to be more viable in terms of simplicity, cross-selectivity and (bio)fouling, besides the fact that its extraction does not disturb individual's well-being. Consequently, simple tests may likely be used for the initial check of the individual in routine analysis, and then, more accurate blood detection of creatinine could be necessary to provide a more genuine diagnosis and/or support the corresponding decision-making by the physician. Herein, we provide a critical discussion of the advantages of current methods of (bio)sensing of creatinine, as well as an overview of the drawbacks that impede their definitive point-of-care establishment.

  • 6.
    Dev, Apurba
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics. Uppsala University, Sweden.
    Horak, J.
    Kaiser, A.
    Yuan, X.
    Perols, A.
    Björk, P.
    Karlström, A. E.
    Kleimann, P.
    Linnros, Jan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Electrokinetic effect for molecular recognition: A label-free approach for real-time biosensing2016In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 82, p. 55-63Article in journal (Refereed)
    Abstract [en]

    We present a simple and inexpensive method for label-free detection of biomolecules. The method monitors the changes in streaming current in a fused silica capillary as target biomolecules bind to immobilized receptors on the inner surface of the capillary. To validate the concept, we show detection and time response of different protein-ligand and protein-protein systems: biotin-avidin and biotin-streptavidin, barstar-dibarnase and Z domain-immunoglobulin G (IgG). We show that specific binding of these biomolecules can be reliably monitored using a very simple setup. Using sequential injections of various proteins at a diverse concentration range and as well as diluted human serum we further investigate the capacity of the proposed technique to perform specific target detection from a complex sample. We also investigate the time for the signal to reach equilibrium and its dependence on analyte concentration and demonstrate that the current setup can be used to detect biomolecules at a concentration as low as 100 pM without requiring any advanced device fabrication procedures. Finally, an analytical model based on diffusion theory has been presented to explain the dependence of the saturation time on the analyte concentration and capillary dimensions and how reducing length and inner diameter of the capillary is predicted to give faster detection and in practice also lower limit of detection. © 2016 Elsevier B.V.

  • 7.
    Gabig-Ciminska, Magdalena
    et al.
    KTH, Superseded Departments, Biotechnology.
    Holmgren, Anders
    KTH, Superseded Departments, Biotechnology.
    Andresen, Heiko
    KTH, Superseded Departments, Biotechnology.
    Barken, K. B.
    Wumpelmann, M.
    Albers, J.
    Hintsche, R.
    Breitenstein, A.
    Neubauer, P.
    Los, M.
    Czyz, A.
    Wegrzyn, G.
    Silfversparre, G.
    Jurgen, B.
    Schweder, T.
    Enfors, Sven-Olof
    KTH, Superseded Departments, Biotechnology.
    Electric chips for rapid detection and quantification of nucleic acids2004In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 19, no 6, p. 537-546Article in journal (Refereed)
    Abstract [en]

    A silicon chip-based electric detector coupled to bead-based sandwich hybridization (BBSH) is presented as an approach to perform rapid analysis of specific nucleic acids. A microfluidic platform incorporating paramagnetic beads with immobilized capture probes is used for the biorecognition steps. The protocol involves simultaneous sandwich hybridization of a single-stranded nucleic acid target with the capture probe on the beads and with a detection probe in the reaction solution, followed by enzyme labeling of the detection probe, enzymatic reaction, and finally, potentiometric measurement of the enzyme product at the chip surface. Anti-DIG-alkaline phosphatase conjugate was used for the enzyme labeling of the DIG-labeled detection probe. p-Aminophenol phosphate (pAPP) was used as a substrate. The enzyme reaction product, p-aminophenol (pAP), is oxidized at the anode of the chip to quinoneimine that is reduced back to pAP at the cathode. The cycling oxidation and reduction of these compounds result in a current producing a characteristic signal that can be related to the concentration of the analyte. The performance of the different steps in the assay was characterized using in vitro synthesized RNA oligonucleotides and then the instrument was used for analysis of 16S rRNA in Escherichia coli extract. The assay time depends on the sensitivity required. Artificial RNA target and 16S rRNA, in amounts ranging from 10(11) to 10(10) molecules, were assayed within 25 min and 4 h, respectively.

  • 8.
    Hao, Nanjing
    et al.
    Department of Chemistry, University of Massachusetts, USA.
    Neranon, Kitjanit
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Department of Chemistry, University of Massachusetts, USA.
    Glyconanomaterials for biosensing applications2016In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 76, no 15, p. 113-130Article in journal (Refereed)
    Abstract [en]

    Nanomaterials constitute a class of structures that have unique physiochemical properties and are excellent scaffolds for presenting carbohydrates, important biomolecules that mediate a wide variety of important biological events. The fabrication of carbohydrate-presenting nanomaterials, glyconanomaterials, is of high interest and utility, combining the features of nanoscale objects with biomolecular recognition. The structures can also produce strong multivalent effects, where the nanomaterial scaffold greatly enhances the relatively weak affinities of single carbohydrate ligands to the corresponding receptors, and effectively amplifies the carbohydrate-mediated interactions. Glyconanomaterials are thus an appealing platform for biosensing applications. In this review, we discuss the chemistry for conjugation of carbohydrates to nanomaterials, summarize strategies, and tabulate examples of applying glyconanomaterials in in vitro and in vivo sensing applications of proteins, microbes, and cells. The limitations and future perspectives of these emerging glyconanomaterials sensing systems are furthermore discussed.

  • 9. Jansod, Sutida
    et al.
    Afshar, Majid Ghahraman
    Crespo, Gaston A.
    Bakker, Eric
    Phenytoin speciation with potentiometric and chronopotentiometric ion-selective membrane electrodes2016In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 79, p. 114-120Article in journal (Refereed)
    Abstract [en]

    We report on an electrochemical protocol based on perm-selective membranes to provide valuable information about the speciation of ionizable drugs, with phenytoin as a model example. Membranes containing varying amounts of tetradodecylammonium chloride (TDDA) were read out at zero current (potentiometry) and with applied current techniques (chronopotentiometry). Potentiometry allows one to assess the ionized form of phenytoin (pKa~8.2) that corresponds to a negatively monocharged ion. A careful optimization of the membrane components resulted in a lower limit of detection (~1.6 µM) than previous reports. Once the pH (from 9 to 10) or the concentration of albumin is varied in the sample (from 0 to 30 g L−1), the potentiometric signal changes abruptly as a result of reducing/increasing the ionized concentration of phenytoin. Therefore, potentiometry as a single technique is by itself not sufficient to obtain information about the concentration and speciation of the drug in the system. For this reason, a tandem configuration with chronopotentiometry as additional readout principle was used to determine the total and ionized concentration of phenytoin. In samples containing excess albumin the rate-limiting step for the chronopotentiometry readout appears to be the diffusion of ionized phenytoin preceded by comparatively rapid deprotonation and decomplexation reactions. This protocol was applied to measure phenytoin in pharmaceutical tables (100 mg per tablet). This tandem approach can likely be extended to more ionizable drugs and may eventually be utilized in view of pharmacological monitoring of drugs during the delivery process.

  • 10.
    Norberg, Oscar
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Lee, Irene H.
    Department of Chemistry, University of Massachusetts.
    Aastrup, Teodor
    Attana AB.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Photogenerated lectin sensors produced by thiol-ene/yne photo-click chemistry in aqueous solution2012In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 34, no 1, p. 51-56Article in journal (Refereed)
    Abstract [en]

    The photoinitiated radical reactions between thiols and alkenes/alkynes (thiol-ene and thiol-yne chemistry) have been applied to a functionalization methodology to produce carbohydrate-presenting surfaces for analyses of biomolecular interactions. Polymer-coated quartz surfaces were functionalized with alkenes or alkynes in a straightforward photochemical procedure utilizing perfluorophenylazide (PFPA) chemistry. The alkene/alkyne surfaces were subsequently allowed to react with carbohydrate thiols in water under UV-irradiation. The reaction can be carried out in a drop of water directly on the surface without photoinitiator, and any disulfide side products were easily washed away after the functionalization process. The resulting carbohydrate-presenting surfaces were evaluated in real-time studies of protein-carbohydrate interactions using a quartz crystal microbalance (QCM) flow-through system with recurring injections of selected lectins, with intermediate regeneration steps using low pH buffer. The resulting methodology proved fast, efficient and scalable to high-throughput analysis formats, and the produced surfaces showed significant protein binding with expected selectivities of the lectins used in the study.

  • 11.
    Pei, Zhichao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Andersson, Henrik
    Aastrup, Teodor
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Study of Real-time Lectin–Carbohydrate Interactions on the Surface of a Quartz Crystal Microbalance2005In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 21, no 1, p. 60-66Article in journal (Refereed)
    Abstract [en]

    A quartz crystal microbalance (QCM) biosensor system for lectin-carbohydrate interactions has been developed. Yeast mannan was immobilised on polystyrene-coated quartz crystals, and interactions tested with the lectin concanavalin A (Con A). The biosensor could be easily operated, where mannan immobilisation and all binding analyses were performed in real-time using a flow-through system. The apparent binding constant for yeast mannan to Con A was estimated to be 0.4 μM, well in accordance to reported literature values. In addition, the effective concentration values (EC50-values) for a series of mannose/mannoside ligands, acting as competitors to the mannan/Con A interaction, were determined to range from 0.18 to 5.3 mM, in good correlation with a related enzyme-labelled lectin assay (ELLA) protocol

  • 12.
    Pei, Zhichao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Larsson, Rikard
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Aastrup, Teodor
    Attana AB.
    Anderson, Henrik
    Uppsala University, Ångström Laboratory, Solid State Electronics.
    Lehn, Jean-Marie
    ISIS-Université Louis Pasteur.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Quartz crystal microbalance bioaffinity sensor for rapid identification of glycosyldisulfide lectin inhibitors from a dynamic combinatorial library2006In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 22, no 1, p. 42-48Article in journal (Refereed)
    Abstract [en]

    Carbohydrate-lectin,interactions were probed with dynamic combinatorial libraries, using the plant lectin Concanavalin A as target species. The dynamic combinatorial libraries were generated from a pool of thiol components through reversible thiol-disulfide interchange, and screened using a simple and efficient method based on a quartz crystal microbalance setup. It was found that dimers based on 1-thio- and 6-thin-mannose analogues were the most active inhibitors. Furthermore, the results clearly show that the 6-thio-mannose possess unique characteristics compared to its oxygen-containing counterpart.

  • 13. Rajasekhar, K.
    et al.
    Narayanaswamy, N.
    Natarajan Arul, Murugan
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Viccaro, K.
    Lee, H. -G
    Shah, K.
    Govindaraju, T.
    Aβ plaque-selective NIR fluorescence probe to differentiate Alzheimer's disease from tauopathies2017In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 98, p. 54-61Article in journal (Refereed)
    Abstract [en]

    Selective detection and staining of toxic amyloid plaques, a potential biomarker present in the Alzheimer's disease (AD) brain is crucial for both clinical diagnosis and monitoring AD disease progression. Herein, we report a coumarin-quinoline (CQ) conjugate-based turn-on near-infrared (NIR) fluorescence probe for specific detection of β-amyloid (Aβ) aggregates. CQ probe is highly sensitive and exhibits ~100-fold fluorescence enhancement in vitro upon binding Aβ aggregates with enhanced quantum yield. Furthermore, the probe has ~10-fold higher binding affinity towards Aβ aggregates (86 nM) compared to commonly used Thioflavin T. Most importantly, CQ probe displays unambiguous selectivity towards Aβ aggregates compared to other toxic protein aggregates such as tau, α-synuclein (α-Syn) and islet amyloid polypeptide (IAPP). In addition, CQ is nontoxic to neuronal cells and shows significant blood brain barrier permeability. Remarkably, CQ stains Aβ plaques in human brain tissue over co-existing tau aggregates and neurofibrillary tangles (NFTs), which are associated in AD and tauopathies. This is a highly desirable attribute to distinguish AD from tau pathology and mixed dementia.

  • 14.
    Ribet, Federico
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Stemme, Göran N.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Roxhed, Niclas
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Ultra-miniaturization of a planar amperometric sensor targeting continuous intradermal glucose monitoring2017In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 90, p. 577-583Article in journal (Refereed)
    Abstract [en]

    An ultra-miniaturized electrochemical biosensor for continuous glucose monitoring (CGM) is presented. The aim of this work is to demonstrate the possibility of an overall reduction in sensor size to allow minimally invasive glucose monitoring in the interstitial fluid in the dermal region, in contrast to larger state-of-the-art systems, which are necessarily placed in the subcutaneous layer. Moreover, the reduction in size might be a key factor to improve the stability and reliability of transdermal sensors, due to the reduction of the detrimental foreign body reaction and of consequent potential failures. These advantages are combined with lower invasiveness and discomfort for patients. The realized device consists of a microfabricated three-electrode enzymatic sensor with a total surface area of the sensing portion of less than 0.04 mm2, making it the smallest fully integrated planar amperometric glucose sensor area reported to date. The working electrode and counter electrode consist of platinum and are functionalized by drop casting of three polymeric membranes. The on-chip iridium oxide (IrOx) pseudo-reference electrode provides the required stability for measurements under physiological conditions. The device is able to dynamically and linearly measure glucose concentrations in-vitro over the relevant physiological range, while showing sufficient selectivity to known interfering species present in the interstitial fluid, with resolution and sensitivity (1.51 nA/mM) comparable to that of state-of-art commercial CGM systems. This work can therefore enable less invasive and improved CGM in patients affected by diabetes.

  • 15.
    Soares, Ruben R. G.
    et al.
    KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Neumann, Felix
    Stockholm Univ, Dept Biochem & Biophys, Sci Life Lab, SE-17165 Solna, Sweden..
    Caneira, Catarina R. F.
    Inst Engn Sistemas & Comp Microsistemas & Nanotec, Lisbon, Portugal.;IN Inst Nanosci & Nanotechnol, Lisbon, Portugal..
    Madaboosi, Narayanan
    Stockholm Univ, Dept Biochem & Biophys, Sci Life Lab, SE-17165 Solna, Sweden..
    Ciftci, Sibel
    Stockholm Univ, Dept Biochem & Biophys, Sci Life Lab, SE-17165 Solna, Sweden..
    Hernandez-Neuta, Ivan
    Stockholm Univ, Dept Biochem & Biophys, Sci Life Lab, SE-17165 Solna, Sweden..
    Pinto, Ines F.
    Inst Engn Sistemas & Comp Microsistemas & Nanotec, Lisbon, Portugal.;IN Inst Nanosci & Nanotechnol, Lisbon, Portugal.;Univ Lisbon, Inst Super Tecn, IBB Inst Bioengn & Biosci, Lisbon, Portugal..
    Santos, Denis R.
    Inst Engn Sistemas & Comp Microsistemas & Nanotec, Lisbon, Portugal.;IN Inst Nanosci & Nanotechnol, Lisbon, Portugal.;Univ Lisbon, Inst Super Tecn, IBB Inst Bioengn & Biosci, Lisbon, Portugal..
    Chu, Virginia
    Inst Engn Sistemas & Comp Microsistemas & Nanotec, Lisbon, Portugal.;IN Inst Nanosci & Nanotechnol, Lisbon, Portugal..
    Russom, Aman
    KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Conde, Joao P.
    Inst Engn Sistemas & Comp Microsistemas & Nanotec, Lisbon, Portugal.;IN Inst Nanosci & Nanotechnol, Lisbon, Portugal.;Univ Lisbon, Inst Super Tecn, Dept Bioengn, Lisbon, Portugal..
    Nilsson, Mats
    Stockholm Univ, Dept Biochem & Biophys, Sci Life Lab, SE-17165 Solna, Sweden..
    Silica bead-based microfluidic device with integrated photodiodes for the rapid capture and detection of rolling circle amplification products in the femtomolar range2019In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 128, p. 68-75Article in journal (Refereed)
    Abstract [en]

    The rapid and sensitive detection of specific nucleic acid sequences at the point-of-care (PoC) is becoming increasingly in demand for a variety of emergent biomedical applications ranging from infectious disease diagnostics to the screening of antimicrobial resistance. To meet such demand, considerable efforts have been invested towards the development of portable and integrated analytical devices combining microfluidics with miniaturized signal transducers. Here, we demonstrate the combination of rolling circle amplification (RCA)-based nucleic acid amplification with an on-chip size-selective trapping of amplicons on silica beads (similar to 8 nL capture chamber) coupled with a thin-film photodiode (200 x 200 mu m area) fluorescence readout. Parameters such as the flow rate of the amplicon solution and trapping time were optimized as well as the photodiode measurement settings, providing minimum detection limits below 0.5 fM of targeted nucleic acids and requiring only 5 mu L of pre-amplified sample. Finally, we evaluated the analytical performance of our approach by benchmarking it against a commercial instrument for RCA product (RCP) quantification and further investigated the effect of the number of RCA cycles and elongation times (ranging from 10 to 120 min). Moreover, we provide a demonstration of the application for diagnostic purposes by detecting RNA from influenza and Ebola viruses, thus highlighting its suitability for integrated PoC systems.

  • 16. Sánchez, J. L. A.
    et al.
    Henry, O. Y. F.
    Joda, H.
    Solnestam, Beata Werne
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Kvastad, Linda
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Johansson, Erik
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Akan, Pelin
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Lundeberg, Joakim
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Lladach, N.
    Ramakrishnan, D.
    Riley, I.
    O'Sullivan, C. K.
    Multiplex PCB-based electrochemical detection of cancer biomarkers using MLPA-barcode approach2016In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 82, p. 224-232Article in journal (Refereed)
    Abstract [en]

    Asymmetric multiplex ligation-dependent probe amplification (MLPA) was developed for the amplification of seven breast cancer related mRNA markers and the MLPA products were electrochemically detected via hybridization. Seven breast cancer genetic markers were amplified by means of the MLPA reaction, which allows for multiplex amplification of multiple targets with a single primer pair. Novel synthetic MLPA probes were designed to include a unique barcode sequence in each amplified gene. Capture probes complementary to each of the barcode sequences were immobilized on each electrode of a low-cost electrode microarray manufactured on standard printed circuit board (PCB) substrates. The functionalised electrodes were exposed to the single-stranded MLPA products and following hybridization, a horseradish peroxidase (HRP)-labelled DNA secondary probe complementary to the amplified strand completed the genocomplex, which was electrochemically detected following substrate addition. The electrode arrays fabricated using PCB technology exhibited an excellent electrochemical performance, equivalent to planar photolithographically-fabricated gold electrodes, but at a vastly reduced cost (>50 times lower per array). The optimised system was demonstrated to be highly specific with negligible cross-reactivity allowing the simultaneous detection of the seven mRNA markers, with limits of detections as low as 25 pM. This approach provides a novel strategy for the genetic profiling of tumour cells via integrated "amplification-to-detection".

  • 17. Tyagi, Anuradha
    et al.
    Wang, Xin
    Deng, Lingquan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Photogenerated carbohydrate microarrays to study carbohydrate-protein interactions using surface plasmon resonance imaging2010In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 26, no 2, p. 344-350Article in journal (Refereed)
    Abstract [en]

    A photochemical strategy to generate carbohydrate microarrays on flat sensor surfaces, and to study the protein-binding effects of these arrays by surface plasmon resonance imaging is described. The approach was validated using a panel of carbohydrate-binding proteins. The coupling agents, thiol-functionalized perfluorophenyl azides, allow the covalent attachment of underivatized carbohydrates to gold surfaces by a fast photochemical reaction. Carbohydrate microarrays composed of 3,6-di-O-(alpha-D-mannopyranosyl)-D-mannopyranose (Man3), 2-O-alpha-D-mannopyranosyl-D-mannopyranose (Man2), D-mannose (Man), D-glucose (Glc), and D-galactose (Gal) were constructed, and the binding studies were carried out in real-time using surface plasmon resonance imaging. Results showed that the immobilized carbohydrate ligands retained their binding affinities with lectins, the rank order of which was consistent with that of the free ligands in solution. The detection limit of Man3, Man2, Man, and Glc with the lectin Concanavalin A was measured to be 0.29 nM, 0.18 nM, 0.61 nM, and 3.1 nM, respectively. In addition, soybean agglutinin and Griffonia simplicifolia lectin II were tested on the array, and the results were consistent with the binding selectivity of these lectins with the carbohydrate ligands.

  • 18. Wang, Xin
    et al.
    Matei, Elena
    Deng, Lingquan
    Koharudin, Leonardus
    Gronenborn, Angela M.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    Sensing lectin-glycan interactions using lectin super-microarrays and glycans labeled with dye-doped silica nanoparticles2013In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 47, p. 258-264Article in journal (Refereed)
    Abstract [en]

    A new microarray platform, based on lectin super-microarrays and glycans labeled with dye-doped nanoparticles, has been developed to study glycan-lectin interactions. Glycan ligands were conjugated onto fluorescein-doped silica nanoparticles (FSNPs) using a general photocoupling chemistry to afford FSNP-labeled glycan probes. Lectins were printed on epoxy slides in duplicate sets to generate lectin super-microarrays where multiple assays could be carried out simultaneously in each lectin microarray. Thus, the lectin super-microarray was treated with FSNP-labeled glycans to screen for specific binding pairs. Furthermore, a series of ligand competition assays were carried out on a single lectin super-microarray to generate the dose-response curve for each glycan-lectin pair, from which the apparent affinity constants were obtained. Results showed 4-7 orders of magnitude increase in affinity over the free glycans with the corresponding lectins. Thus, the glycan epitope structures having weaker affinity than the parent glycans could be readily identified and analyzed from the lectin super-microarrays.

  • 19. Zhang, F.
    et al.
    Liang, X.
    Zhang, W.
    Wang, Yong-Lei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Wang, H.
    Mohammed, Y. H.
    Song, B.
    Zhang, R.
    Yuan, J.
    A unique iridium(III) complex-based chemosensor for multi-signal detection and multi-channel imaging of hypochlorous acid in liver injury2017In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 87, p. 1005-1011Article in journal (Refereed)
    Abstract [en]

    Although hypochlorous acid (HOCl) has long been associated with a number of inflammatory diseases in mammalian bodies, the functions of HOCl in specific organs at abnormal conditions, such as liver injury, remain unclear due to its high reactivity and the lack of effective methods for its detection. Herein, a unique Ir(III) complex-based chemosensor, Ir-Fc, was developed for highly sensitive and selective detection of HOCl. Ir-Fc was designed by incorporating a ferrocene (Fc) quencher to a Ir(III) complex through a HOCl-responsive linker. In the presence of HOCl, the fast cleavage of Fc moiety in less than 1 s led to the enhancement of photoluminescence (PL) and electrochemical luminescence (ECL), by which the concentration of HOCl was determined by both PL and ECL analysis. Taking advantages of excellent properties of Ir(III) complexes, optical and electrochemical analyses of the response of Ir-Fc towards HOCl were fully investigated. Followed by the measurements of low cytotoxicity of Ir-Fc by MTT analysis, one-photon (OP), two-photon (TP) and lifetime imaging experiments were conducted to visualise the generation of HOCl in live microphage and HepG2 cells, and in zebrafish and mouse, respectively. Furthermore, the generation and distribution of HOCl in liver cells and liver injury of zebrafish and mouse were investigated. The results demonstrated the applicability of Ir-Fc as an effective chemosensor for imaging of HOCl generation in mitochondria of cells and liver injury in vivo, implying the potential of Ir-Fc for biomedical diagnosis and monitoring applications. © 2016 Elsevier B.V.

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