| 1. |
- Ahmad Tajudin, Asilah
(författare)
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Biomarker detection via lab-on-a-chip integrated immunoaffinity approach for fluorescence and mass spectrometry readout
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The blood/plasma protein biomarker profile represents the pathological and physiological changes relating to human diseases. However, the plasma proteome reflects a high degree of complexity that results in a challenge for most analytical methods in clinical diagnostics. The focus in this thesis is the development and application of several integrated platforms to detect already established protein/peptide biomarkers from blood and plasma (Prostate Specific Antigen, PSA and Angiotensin I, Ang I). The integrated platforms that are described in the papers included in this thesis utilize protein/peptide immunoaffinity-capturing since it offers insights into dealing with the challenges of the plasma proteome analysis by reducing complexity and enriching the proteins/peptides of interest. Several integrated platforms were developed with the overall main aim of detecting biomarkers from complex biological samples: • porous silicon antibody microarray with signal amplification step (Paper I) • microfluidic whole blood immunoassay (Paper II and III) • integrated protein immunoaffinity capturing with microfabricated proteomic sample processing platform (ISET) enabling a direct interface to MALDI MS/MS analysis (Paper IV) • integrated peptide immunoaffinity capturing via porous silicon array-based immuno-MALDI (Paper V) enabling a direct interface to MALDI MS/MS analysis Ultimately, these platforms target future use in point-of-care settings (Paper I-III) and immuno-MALDI mass spectrometry immunoassays for identification and quantitative measurements of biomarkers using isotope labelled standards (Paper V) as well as outlook for use in the development of SRM/MRM assays (Paper IV).
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| 2. |
- Ahmad Tajudin, Asilah, et al.
(författare)
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Integrated acoustic immunoaffinity-capture (IAI) platform for detection of PSA from whole blood samples.
- 2013
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Ingår i: Lab on a Chip. - : Royal Society of Chemistry (RSC). - 1473-0189 .- 1473-0197. ; 13:9, s. 1790-1796
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Tidskriftsartikel (refereegranskat)abstract
- On-chip detection of low abundant protein biomarkers is of interest to enable point-of-care diagnostics. Using a simple form of integration, we have realized an integrated microfluidic platform for the detection of prostate specific antigen (PSA), directly in anti-coagulated whole blood. We combine acoustophoresis-based separation of plasma from undiluted whole blood with a miniaturized immunoassay system in a polymer manifold, demonstrating improved assay speed on our Integrated Acoustic Immunoaffinity-capture (IAI) platform. The IAI platform separates plasma from undiluted whole blood by means of acoustophoresis and provides cell free plasma of clinical quality at a rate of 10 uL/min for an online immunoaffinity-capture of PSA on a porous silicon antibody microarray. The whole blood input (hematocrit 38-40%) rate was 50 μl min(-1) giving a plasma volume fraction yield of ≈33%. PSA was immunoaffinity-captured directly from spiked female whole blood samples at clinically significant levels of 1.7-100 ng ml(-1) within 15 min and was subsequently detected via fluorescence readout, showing a linear response over the entire range with a coefficient of variation of 13%.
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| 3. |
- Ahmad Tajudin, Asilah, et al.
(författare)
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MALDI-target integrated platform for affinity-captured protein digestion.
- 2014
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Ingår i: Analytica Chimica Acta. - : Elsevier BV. - 1873-4324 .- 0003-2670. ; 807:Jan 7, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- To address immunocapture of proteins in large cohorts of clinical samples high throughput sample processing is required. Here a method using the proteomic sample platform, ISET (integrated selective enrichment target) that integrates highly specific immunoaffinity capture of protein biomarker, digestion and sample cleanup with a direct interface to mass spectrometry is presented. The robustness of the on-ISET protein digestion protocol was validated by MALDI MS analysis of model proteins, ranging from 40fmol to 1pmol per nanovial. On-ISET digestion and MALDI MS/MS analysis of immunoaffinity captured disease-associated biomarker PSA (prostate specific antigen) from human seminal plasma are presented.
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| 4. |
- Lenshof, Andreas, et al.
(författare)
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Acoustic Whole Blood Plasmapheresis Chip for Prostate Specific Antigen Microarray Diagnostics.
- 2009
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 1520-6882 .- 0003-2700. ; 81:Jul 13, s. 6030-6037
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Tidskriftsartikel (refereegranskat)abstract
- The generation of high quality plasma from whole blood is of major interest for many biomedical analyses and clinical diagnostic methods. However, it has proven to be a major challenge to make use of microfluidic separation devices to process fluids with high cell content, such as whole blood. Here, we report on an acoustophoresis based separation chip that prepares diagnostic plasma from whole blood linked to a clinical application. This acoustic separator has the capacity to sequentially remove enriched blood cells in multiple steps to yield high quality plasma of low cellular content. The generated plasma fulfills the standard requirements (<6.0 x 10(9) erythrocytes/L) recommended by the Council of Europe. Further, we successfully linked the plasmapheresis microchip to our previously developed porous silicon sandwich antibody microarray chip for prostate specific antigen (PSA) detection. PSA was detected by good linearity (R(2) > 0.99) in the generated plasma via fluorescence readout without any signal amplification at clinically relevant levels (0.19-21.8 ng/mL).
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| 5. |
- Lenshof, Andreas, et al.
(författare)
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Acoustic whole blood plasmapheresis chip for PSA microarray diagnostics
- 2009
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Ingår i: Proceedings of Conference, MicroTAS 2009 : The 13th International Conference on Miniaturized Systems for Chemistry and Life Sciences - The 13th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9780979806421 ; , s. 1330-1332
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Konferensbidrag (refereegranskat)abstract
- An acoustic device for generating high quality blood plasma for PSA microarray diagnostics is presented.
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| 6. |
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| 7. |
- Syamila, Noor, et al.
(författare)
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Displacement of PAMAM-Au via acoustic streaming on an electrochemical immunosensing platform
- 2024
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Ingår i: Journal of Micromechanics and Microengineering. - 0960-1317. ; 34:1
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Tidskriftsartikel (refereegranskat)abstract
- The displacement of an electroactive monitoring agent, i.e., polyamidoamine dendrimers encapsulated gold nanoparticles (PAMAM-Au) upon the presence of a target antibody via acoustic streaming has been studied. Acoustic streaming has been used to improve the mass transfer and reduce the sample incubation rate, thus this study investigated its ability in enhancing the PAMAM-Au displacement efficiency of our immunosensor. For this purpose, the bio-nanogate components of maltose-binding protein carrying the antigenic determinant (MBP-aD) of hepatitis B surface antigen (HBsAg) as a bioreceptor was functionalized, followed by the monitoring agent i.e. PAMAM-Au on the electrode prior to the incubation with targeted anti-hepatitis B surface antigen (anti-HBsAg) antibody. The modified electrode was then coupled with a piezotransducer and connected to the signal transducer to induce acoustic streaming upon sample incubation. Under optimal acoustic actuation, the sample incubation time has been reduced from 20 min to 8 min via the enhancement of PAMAM-Au displacement induced by acoustic streaming. The result also demonstrated that the specificity and selectivity of the sensing platform under acoustic actuation are comparable to the static incubation in detecting the targeted antibody.
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| 8. |
- Tajudin, Asilah Ahmad, et al.
(författare)
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Maldi-target integrated microfluidic PSA assay
- 2009
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Ingår i: Proceedings of Conference, MicroTAS 2009 - The 13th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9780979806421 ; , s. 1064-1066
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Konferensbidrag (refereegranskat)abstract
- An Integrated Selective Enrichment Target (ISET), microfabricated for efficient on-bead enzymatic digestion of proteins compatible for a direct interface with matrix-assisted laser desorption /ionization mass spectrometry (MALDI MS) is presented.
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| 9. |
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| 10. |
- Yan, Hong, et al.
(författare)
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Noncovalent antibody immobilization on porous silicon combined with miniaturized Solid-Phase Extraction (SPE) for array based immunoMALDI assays
- 2011
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 1520-6882 .- 0003-2700. ; 83, s. 4942-4948
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a new strategy to combine the power of antibody based capturing of target species in complex samples with the benefits of microfluidic reverse phase sample preparation on an integrated sample enrichment target (RP-ISET) and the analysis speed of MALDI MS. The immunoaffinity step is performed on an in-house developed 3D-structured high surface area porous silicon (PSi) matrix, which allows efficient antibody immobilization by surface adsorption without any coupling agents in 30-60 min. The hydrophilic nature of the porous silicon surface at the molecular level displays a low adsorption of background peptides when exposed to complex digests or plasma samples, improving the conditions for the antigen specific extraction and subsequent readout. At the same time, the hydrophobic behavior, due to the nanostructured surface, of the PSi material facilitates liquid confinement during the assay. Using a footprint conforming to the standard for 384 well microplates, direct adaption of the protocol into standard sample handling robots is possible. The performance of the proposed immunoaffinity PSi-ISET immunoMALDI (iMALDI) assay was evaluated by specific detection of angiotensin I at a 10 femtomol level in diluted plasma samples (10 μL, 1 nM).
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