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  • 1.
    Antypas, H.
    et al.
    Karolinska Inst, Dept Neurosci, Swedish Med Nanosci Ctr, Stockholm, Sweden..
    Veses-Garcia, M.
    Karolinska Inst, Dept Neurosci, Swedish Med Nanosci Ctr, Stockholm, Sweden..
    Weibull, Emelie
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science.
    Svahn Andersson, Helene
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Richter-Dahlfors, A.
    Karolinska Inst, Dept Neurosci, Swedish Med Nanosci Ctr, Stockholm, Sweden..
    A universal platform for selection and high-resolution phenotypic screening of bacterial mutants using the nanowell slide2018In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 18, no 12, p. 1767-1777Article in journal (Refereed)
    Abstract [en]

    The Petri dish and microtiter plate are the golden standard for selection and screening of bacteria in microbiological research. To improve on the limited resolution and throughput of these methods, we developed a universal, user-friendly platform for selection and high-resolution phenotypic screening based on the nanowell slide. This miniaturized platform has an optimal ratio between throughput and assay complexity, holding 672 nanowells of 500 nl each. As monoclonality is essential in bacterial genetics, we used FACS to inoculate each nanowell with a single bacterium in 15 min. We further extended the protocol to select and sort only bacteria of interest from a mixed culture. We demonstrated this by isolating single transposon mutants generated by a custom-made transposon with dual selection for GFP fluorescence and kanamycin resistance. Optical compatibility of the nanowell slide enabled phenotypic screening of sorted mutants by spectrophotometric recording during incubation. By processing the absorbance data with our custom algorithm, a phenotypic screen for growth-associated mutations was performed. Alternatively, by processing fluorescence data, we detected metabolism-associated mutations, exemplified by a screen for -galactosidase activity. Besides spectrophotometry, optical compatibility enabled us to perform microscopic analysis directly in the nanowells to screen for mutants with altered morphologies. Despite the miniaturized format, easy transition from nano- to macroscale cultures allowed retrieval of bacterial mutants for downstream genetic analysis, demonstrated here by a cloning-free single-primer PCR protocol. Taken together, our FACS-linked nanowell slide replaces manual selection of mutants on agar plates, and enables combined selection and phenotypic screening in a one-step process. The versatility of the nanowell slide, and the modular workflow built on mainstream technologies, makes our universal platform widely applicable in microbiological research.

  • 2.
    Banerjee, Indradumna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Point of care microfluidic tool development for resource limited settings2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The development of point of care diagnostics using recent advances in microfluidics have the potential to transform health care in several ways, especially in resource limited settings with limited access to advanced health care infrastructure. However, translating a point of care device to reality is often a challenging task because of the complexities involved in integrating a number of diverse engineering concepts into an easy to use, accurate and portable device. This thesis focuses on miniaturization of crucial diagnostic laboratory tools, that can be used in a portable point of care format without compromising on the accuracy or performance. The first part of the thesis (Paper I-III) focuses on understanding and applying elasto-inertial microfluidics, which is a label-free and passive bio-particle sorting and separation method. A basic understanding of particle trajectories in both inertial (Paper I) and visco-elastic flows (Paper II) is established, followed by an investigation on the combined effects of inertia and elasticity (Paper III). The second part of the thesis (Paper IV-VI) focuses on developing integrated microfluidic platforms, each of which addresses different aspects of point of care diagnostic applications. The applications include neonatal diagnostics using a hand-driven Slipdisc technique (Paper IV), rapid nucleic acid quantification using a novel precipitate-based detection on a centrifugal microfluidics platform (Paper V), and hematocrit level measurement in blood using a portable lab-on- Disc platform operated by a mobile phone (Paper VI). The proof of concept microfluidic tools presented in the scope of this thesis have the potential to replace a number of functions of standard laboratory equipment, at a fraction of the price and without compromising performance. Hence, the different methods developed should contribute towards decentralization of medical testing laboratories, making healthcare accessible to one and all.

  • 3.
    Banerjee, Indradumna
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Ganeshappa Aralaguppe, Shambhu Prasad
    Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institute, Sweden..
    Lapins, Noa
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Zhang, Wang
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab. Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institute, Sweden..
    Kazemzadeh, Amin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Sönnerborg, Anders
    Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institute, Sweden..
    Neogi, Ujjwal
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology. Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institute, Sweden..
    Russom, Aman
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Microfluidic Centrifugation Assisted Precipitation based DNA QuantificationManuscript (preprint) (Other academic)
    Abstract [en]

    Nucleic acid amplification methods are increasingly being used to detect trace quantities of DNA in samples for various diagnostic applications. However, quantifying the amount of DNA from such methods often require time consuming purification, washing or labeling step. Here, we report a novel microfluidic centrifugation assisted precipitation (uCAP) method for single-step DNA quantification. The method is based on formation of a visible precipitate, that can be quantified, when an intercalating dye (GelRed) is added to DNA sample and centrifuged for few seconds. We describe the mechanism leading to the precipitation phenomenon. We utilize centrifugal microfluidics to precisely control the formation of visible and quantifiable mass. Using a standard CMOS sensor for imaging, we report a detection limit of 45 ng/ul. Furthermore, using an integrated Lab-on-DVD platform we recently developed, the detection limit was lowered to 10 ng/ul, which is comparable to current commercially available instruments for DNA quantification. As a proof of principle, we demonstrate the quantification of LAMP products for a HIV-1B type genome containing plasmid on the Lab-on-DVD platform. The simple DNA quantification system could facilitate advanced molecular diagnosis at point of care.

  • 4.
    Banerjee, Indradumna
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Rosti, Marco Edoardo
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Kumar, Tharagan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Brandt, Luca
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Russom, Aman
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Analog particle position tuning in Elasto-inertial microfluidic flowsManuscript (preprint) (Other academic)
    Abstract [en]

    We observe for the first time an analog trend in particle focusing in a high throughput weakly viscoelastic regime, where it is possible to tune particles into multiple intermediate focusing positions that lie between the "Segre-Silberberg annulus" and the center of a circular microcapillary. The "Segre-Silberberg annulus" (0.6 times the pipe radius), that describes particle equilibrium in a predominantly inertial flow, shrinks consistently closer to the center for increasing elasticity in extremely dilute PEO concentrations (ranging from 0.001 wt% to 0.05wt%). The experimental observations are supported by direct numerical simulations, where an Immersed Boundary Method is used to account for the presence of particles and a FENE-P model is used to simulate the presence of polymers in a Non-Newtonian fluid. The numerical simulations study the dynamics and stability of finite size particles and are further used to analyze particle behavior at Reynolds number higher than what is allowed by the present experimental setup. In particular, we are able to report the entire migration trajectories of the particles as they reach their final equilibrium positions and extend our predictions to other geometries such as the square cross-section. We believe complex effects originate due to a combination of inertia and elasticity in a weakly viscoelastic regime, where neither inertia nor elasticity are able to mask each other's effect completely, thus leading to a number of intermediate focusing positions. The present study provides a new understanding into the mechanism of particle focusing in elasto-inertial flows and opens up new possibilities for exercising analog control in tuning the particle focusing positions.

  • 5.
    Banerjee, Indradumna
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Rosti, Marco Edoardo
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Kumar, Tharagan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Brandt, Luca
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Russom, Aman
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Particle focusing dynamics in extended elasto inertial flow2018Conference paper (Refereed)
    Abstract [en]

    Elasto Inertial microfluidics has been exploited recently for a number of industrial and biological applications. Recently, we experimentally showed that it is possible to achieve single stream focusing of particles even at higher flow rates in the elasto inertial regime, relevant to flow cytometry applications, and , based on this concept, built a silica fibre based micro flow cytometer.1 However, the physics behind the focusing of particles is still poorly understood, specially for combinations of higher Reynolds (Re) and Weissenberg numbers(Wi).

    In the present study, for the first time, we seek to understand both experimentally and with numerical simulations, particle focusing across elasticity regimes. We vary the concentration of PEO (200 ppm to upto 10000 ppm) in PBS solution at sufficiently high flow rates of 100!l/min or above. We introduce a parameter, focusing bandwidth (F) to evaluate the extent of single stream focusing of 15 !m particles in a 75 !m diameter circular channel. Fig.1 shows the flow setup(fig.1a) along with images demonstrating the focused (fig.1b) and unfocused cases(fig.1c), as well as how F is calculated(fig.1d). We evaluate particle focusing by identifying the flow conditions for each concentration that leads to the minimum value of F. Fig.2 shows the variation of the focusing bandwidth(fig.2a) when changing PEO concentration, and the variation in Re along with Wi (fig.2b) and Elasticity number(El). The results show that for identical mass flow conditions across the different regimes the focusing bandwidth slowly shifts to a narrow single stream with increasing elasticity. We validated our experimental results as well as gained new insights into particle focusing with 3D numerical simulations based on a FENE P model. We studied the decoupled effects of Reynolds number and Weissenberg number on particle focusing, as well as the particle trajectories and migration dynamics as the particles reach equilibrium. Interestingly, enough we find a combination of high Re(Re=400) and sufficiently high Wi(Wi=3) for which the particles achieve a single stream focusing (fig.3a). The entire dynamics of particle migration in a circular cross section is also shown (in fig.3b) by changing Wi for a constant Re(Re=200). It can be seen that the particle goes through a longer amount of oscillations to reach its final equilibrium position as Wi is increased. Fig.4a shows the equilibrium position of the particle moving closer to the center with an increase in Wi at the same Re(Re=200). However, in the Non Newtonian cases, the particle has a slight oscillatory behaviour as it reaches its equilibrium position as compared to the Newtonian one. We introduced the particle at two different positions(at Re=200, We=0 and 1) and observed the same equilibrium positions in both cases (Fig.4b).

  • 6.
    Banerjee, Indradumna
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Russom, Aman
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Lab-on-DVD: Optical Disk Drive-Based Platforms for Point-of-Care Diagnostics2018In: Frugal Innovation in Bioengineering for the Detection of Infectious Diseases / [ed] AK Chavali, R Ramji, Switzerland: Springer, 2018, 2, p. 23-38Chapter in book (Refereed)
    Abstract [en]

    There is a growing demand for simple, affordable, reliable and quality-assured point-of-care (POC) diagnostics for use in resource-limited settings. Among the top ten leading causes of death worldwide, three are infectious diseases, namely, respiratory infections, HIV/AIDS and diarrheal diseases (World Health Organization 2012). Although high-quality diagnostic tests are available, these are often not available to patients in developing countries. While recent development in microfluidics and “lab-on-a-chip” devices has the potential to spur the development of protocols and affordable instruments for diagnosis of infectious disease at POC, integration of complex sample preparation and detection into automated molecular and cellular systems remain a bottleneck for implementation of these systems at resource-limited settings. Towards this, we describe here how low-cost optical drives can, with minor modifications, be turned into POC diagnostic platforms. A DVD drive is essentially a highly advanced and low-cost optical laser-scanning microscope, with the capability to deliver high-resolution images for biological applications. Furthermore, the inherent centrifugal force on rotational discs is elegantly used for sample preparation and integration. Hence, the merging of low-cost optical disc drives with centrifugal microfluidics is feasible concept for POC diagnostics, specifically designed to meet the needs at resource-limited settings.

  • 7.
    Banerjee, Indradumna
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Russom, Aman
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    MicroCAP2018Patent (Other (popular science, discussion, etc.))
    Abstract [en]

  • 8.
    Faridi, Muhammad Asim
    et al.
    KTH.
    Shahzad, Adnan Faqui
    KTH.
    Russom, Aman
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Milliliter scale acoustophoresis based bioparticle processing platform2018In: ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2018, ASME Press, 2018Conference paper (Refereed)
    Abstract [en]

    Bioparticles such as mammalian cells and bacteria can be manipulated directly or indirectly for multiple applications such as sample preparation for diagnostic applications mainly up-concentration, enrichment & separation as well as immunoassay development. There are various active and passive microfluidic particle manipulation techniques where Acoustophoresis is a powerful technique showing high cell viability. The use of disposable glass capillaries for acoustophoresis, instead of cleanroom fabricated glass-silicon chip can potentially bring down the cost factor substantially, aiding the realization of this technique for real-world diagnostic devices. Unlike available chips and capillary-based microfluidic devices, we report milliliter-scale platform able to accommodate 1ml of a sample for acoustophoresis based processing on a market available glass capillary. Although it is presented as a generic platform but as a demonstration we have shown that polystyrene suspending medium sample can be processed with trapping efficiency of 87% and the up-concentration factor of 10 times in a flow through manner i.e., at 35µl/min. For stationary volume accommodation, this platform practically offers 50 times more sample handling capacity than most of the microfluidic setups. Furthermore, we have also shown that with diluted blood (0.6%) in a flow-through manner, 82% of the white blood cells (WBCs) per ml could be kept trapped. This milliliter platform could potentially be utilized for assisting in sample preparation, plasma separation as well as a flow-through immunoassay assay development for clinical diagnostic applications.

  • 9. Fornell, Anna
    et al.
    Nilsson, Johan
    Jonsson, Linus
    Periyannan Rajeswari, Prem
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Joensson, Haakan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Tenje, Maria
    Particle enrichment in two-phase microfluidic systems using acoustophoresis2016In: Acoustofluidics 2016, Kongens Lyngby, Denmark, September 22-23 2016, 2016Conference paper (Refereed)
  • 10. Fornell, Anna
    et al.
    Nilsson, Johan
    Jonsson, Linus
    Periyannan Rajeswari, Prem Kumar
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Jönsson, Håkan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Tenje, Maria
    Particle enrichment in droplet acoustofluidics2016In: Micronano System Workshop (MSW 2016), Lund, Sweden, May 17-18 2016, 2016Conference paper (Refereed)
  • 11. Jeong, Yunjin
    et al.
    Svedberg, Gustav
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Réu, Pedro
    Lee, Yongju
    Song, Seo Woo
    Na, Hunjong
    Lee, Amos Chungwon
    Choi, Yeongjae
    Gantelius, Jesper
    Andersson Svahn, Helene
    Kwon, Sunghoon
    Solid-phase PCR on graphically encoded microparticles for multiplexed colorimetric detection of bacterial DNAManuscript (preprint) (Other academic)
  • 12.
    Kazemzadeh, Amin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Eriksson, Anders
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Madou, Marc
    Univ Calif Irvine, Dept Mech & Aerosp Engn, Irvine, CA 92697 USA..
    Russom, Aman
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    A micro-dispenser for long-term storage and controlled release of liquids2019In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, no 1, article id 189Article in journal (Refereed)
    Abstract [en]

    The success of lab-on-a-chip systems may depend on a low-cost device that incorporates on-chip storage and fluidic operations. To date many different methods have been developed that cope separately with on-chip storage and fluidic operations e. g., hydrophobic and capillary valves pneumatic pumping and blister storage packages. The blister packages seem difficult to miniaturize and none of the existing liquid handling techniques despite their variety are capable of proportional repeatable dispensing. We report here on an inexpensive robust and scalable micro-dispenser that incorporates long-term storage and aliquoting of reagents on different microfluidics platforms. It provides long-term shelf-life for different liquids enables precise dispensing on lab-on-a-disc platforms and less accurate but proportional dispensing when operated by finger pressure. Based on this technology we introduce a method for automation of blood plasma separation and multi-step bioassay procedures. This micro-dispenser intends to facilitate affordable portable diagnostic devices and accelerate the commercialization of lab-on-a-chip devices.

  • 13.
    Kazemzadeh, Amin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Lapins, Noa
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Banerjee, Indradumna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Akhtar, Ahmad Saleem
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Russom, Aman
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Mobile-LabDisc for Point-of-Care DiagnosticsManuscript (preprint) (Other academic)
    Abstract [en]

    At resource limited settings, point of care devices require a very low-cost, robust and easy to use platform that is preferably capable of automating and multiplexing intricate bioassays. We report on a mobile lab-disc platform that is specifically designed to meet the needs at resource- limited settings. It uses a smartphone as an electrical power source and a disposable, rigid and portable casing made of cardboard that securely accommodate the entire lab-disc system rotor, lightning and wiring and other accessories. The mobile lab-disc is light, less-expensive and functional at places where the electrical power infrastructure is not available. We show that the electrical energy stored in most mobile phones can be used for spinning a lab-Disc at up to 5500 rpm, a speed sufficient for most of the required functional steps in a bioassay including ELISA. We develop individual components of the mobile lab-disc system by experimentally conducting colorimetric assays using HRP and sandwich immunoassay. Finally, the full potential of the mobile lab-disc for integrating and multiplexing bioassays is demonstrated by measuring the hematocrit level in whole blood. The mobile phone-operated process integrates sample preparation i.e., blood-plasma separation, imaging and image analysis. The total cost of our prototype system for the tests, excluding the phone is ~$5, assuming that a lab-disc unit is worth $1.

  • 14.
    Langer, Krzysztof
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Jönsson, Håkan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Rapid production and recovery of cell spheroids by automated droplet microfluidics2019In: bioRxivArticle in journal (Refereed)
    Abstract [en]

    Droplet microfluidics enables high throughput cell processing, analysis and screening by miniaturizing the reaction vessels to nano- or pico-liter water-in oil droplets, but like many other microfluidic formats, droplet microfluidics have not been interfaced with or automated by laboratory robotics. Here we demonstrate automation of droplet microfluidics based on an inexpensive liquid handling robot for the automated production of human scaffold-free cell spheroids, using pipette actuation and interfacing the pipetting tip with a droplet generating microfluidic chip. In this chip we produce highly mono-disperse 290μm droplets with diameter CV of 1.7%. By encapsulating cells in these droplets, we produce cell spheroids in droplets and recover them to standard formats at a throughput of 85000 spheroids per microfluidic circuit per hour. The viability of the cells in spheroids remains high after recovery only decreased by 4% starting from 96% after 16 hours incubation in nanoliter droplets. Scaffold-free cell spheroids and 3D tissue constructs recapitulate many aspects of functional human tissue more accurately than 2D or single cell cultures, but assembly methods for spheroids, e.g. hanging drop micro-plates, has had limited throughput. The increased throughput and decreased cost of our method enables spheroid production at the scale needed for lead discovery drug screening and approaches the cost where these micro tissues could be used as building blocks for organ scale regenerative medicine.

  • 15. Sangeeta, K.
    et al.
    Jain, Saumey
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Satija, J.
    Investigation of bimetallic hollow nanoparticles for colorimetric detection of mercury2018In: Nanophotonics VII 2018, SPIE , 2018, Vol. 10672, article id UNSP 106723QConference paper (Refereed)
    Abstract [en]

    In this study, we have investigated the potential of bimetallic hollow nanostructures (BHNS) consisting of silver and gold metals for the detection of mercury in an aqueous medium. The BHNS of varying compositions of gold and silver were prepared by galvanic etching of the template silver nanoparticles (AgNPs) using gold(III) salt solution. The BHNS of varying composition were prepared by modulating the molar ratio, of gold to silver, ranging from 0.13 to 2.0, in the reaction mixture. The resultant nanostructures were characterized using UV-Vis spectroscopy and transmission electron microscopy. The absorption maxima of the BHNS batches were found to be increased from 463 ± 9 nm to 611 ± 12 nm as a function of gold to silver molar ratio. An increase in the nanoparticles size was observed from 54 ± 6 (molar ratio = 0.25) to 75 ± 10 (molar ratio = 2.0) with an increase in gold to silver molar ratio. The interaction of different volumes of mercury solution (ranging from 0.1 to 0.4 mL) with all types of BHNS was studied. A considerable change in color of the solution was observed and consequently, a change in the absorbance intensity and a shift in the peak plasmonic wavelength was also noticed. Among the different BHNS batches investigated, the highest change in the intensity and peak wavelength was observed for BHNS0.13, with higher silver and lower gold content. This suggests that the reaction between silver and mercury is more favored compared to that between mercury and gold.

  • 16.
    Svedberg, Gustav
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Novel planar and particle-based microarrays for point-of-care diagnostics2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Point-of-care assays are easy-to-use, portable and inexpensive tests that can

    be used to aid diagnostics by measuring levels of disease-specific molecules

    in settings where access to advanced laboratory equipment and trained

    personnel are limited, such as at the patient's bedside or in low resource

    parts of developing countries. In order to achieve high multiplexing

    capacities, such assays can be based on planar microarrays consisting of

    spots immobilized on a flat surface or on particle-based microarrays based

    on populations of encoded particles. The aim of the work presented in this

    thesis is to develop new point-of-care amenable planar and particle-based

    microarrays that allow for highly multiplexed assays while maintaining low

    sample-to-result times, complexity and instrumentation requirements.

    Paper I demonstrates the use graphically encoded particles for colorimetric

    detection of autoantibodies using a consumer-grade flatbed scanner. Four

    graphical characters on the surface of each particle allows for millions of

    codes and the use of gold nanoparticles as a detection label allows both the

    code and the signal intensity to be read out in a single image.

    Paper II describes a signal enhancement method that increases the

    sensitivity of gold nanoparticle detection on planar microarrays. Using this

    method, detection of allergen-specific IgE can be carried out using a

    consumer-grade flatbed scanner instead of a more expensive fluorescence

    scanner without sacrificing assay performance.

    Paper III demonstrates the use of an isothermal DNA amplification method

    for detection of adenoviral DNA on a paper-based microarray. Using an

    isothermal amplification method eliminates the need for a thermocycler,

    reducing the instrumentation required for such detection.

    Paper IV shows the use of solid-phase PCR to amplify bacterial DNA directly

    on the surface of particles. This strategy reduces assay time by eliminating

    the need for separate amplification and hybridisation steps.

  • 17.
    Zhang, Wang
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology. karolinska institutet.
    Aljadi, Zenib
    Neogi, Ujjwal
    Russom, Aman
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Microfluidic based immunoaffinity mononuclear leukocytes isolation from whole bloodManuscript (preprint) (Other academic)
    Abstract [en]

    CD4+ T cells, monocyte/macrophages and natural killer cells are believed to be the main source for HIV-1 reservoirs in peripheral blood. However, despite the potential these subsets of providing a wealth of new information about immune function and host pathology, current HIV latency studies are often based on PBMCs or only CD4+ T cells, mainly due to the lack of appropriate cell subset isolation methods. We present here a microfluidic chip-based method to capture and enrich the three mononuclear cells sub-population peripheral leukocyte sub-populations: CD4+ lymphocytes, natural killer cells and monocytes; using a single source of whole blood (volume < 200 μL) on a single integrated platform, within a time frame of 20 min. The single step isolation method can be used for downstream proteomics and genomics analysis to study the aberrations in these cell types’ functions in critical diseases such as HIV.

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