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Fluorescent quantum dots and graphene-based sensors for forensic applications
KTH, School of Engineering Sciences (SCI), Applied Physics. 1989. (Ying Fu)ORCID iD: 0000-0002-3606-8985
2019 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

A key emerging concept within the forensic sciences today areportable measurementdevices, where a much more efficient usage of the resources involved with crime-solving is possible if confirmatory measurements can be realised directly at a crimescene with such devices. Today, the majority of the presently used methods duringcriminal investigation at a crime scene involves measurements of a presumptivenature, which is a vital tool as it enables the screening of samples. In this thesis,the overarching goal is the development of tool kits for the analysis of biosampleson-site at a crime scene. This is mainly investigated through two routes: theusage of Quantum Dots (QDs) as a recognition element in sensory applications andfabrication of a graphene-based device for the detection of illicit drugs.The investigations conducted for the studies presented in this thesis focuses onsensory applications with a forensic detection scheme in mind: study I reveals in-trinsic properties of QDs to better understand sensing mechanisms upon bindinginteractions; study II demonstrates the fabrication of a graphene-based device forthe detection of illicit drugs; study III showcases the functionalised and bioconju-gated of QDs for a specific investigation into a biological process; study IV furtherthe investigation into the possible side-effects of QDs on biological specimens.In study I we numerically and experimentally investigate the intrinsic blinkingcharacteristics of CdSe-CdS/ZnS QDs. This includes a thorough examination of theexperimental parameters of the measurement setup: the bin time and excitationpower. Different mechanisms between the off- and on-state probability distributionsare found, wherein the on-state follows the random telegraph signal theory and theoff-state follows the inverse power law distribution.In study II, the detection of illicit drugs (amphetamine and cocaine) is achievedthrough graphene-based sensors processed to contain metal electrodes with superioradhesion and low contact resistance. The construction of a microfluidic system isfurther realised for a detection of molecules based on non-covalent interactions.With this system, a wavelength-dependent photoactivity for amphetamine and arange of its chemical analogs is demonstrated. A molecule dependent interactionwith the graphene surface is shown of the graphene surface either in the form ofp-doping (cocaine) or n-doping (amphetamine).Study III investigates the endocytic pathway of the vascular cell adhesionmolecule 1 (VCAM1) in Human Umbilical Vein Endothelial Cells (HUVECs) in-iiiivABSTRACTduced by Tumor Necrosis Factorα(TNFα) with the usage of 3-Mercaptopropionicacid coated (3MPA)-QDs and 5-Carboxyfluorescein (5FAM) functionalised and la-belled with VCAM1 binding peptides, respectively. Internalisation of the VCAM1molecules into lysosomes is shown with light microscopy through observations ofdifferent pathways of the 5FAM labelled peptides and functionalised QDs.In study IV we investigate the adverse effects of 3MPA-QDs on the humanairway epithelium by an examination of the calcium response in lung cells upon astimulation with QDs. The cellular response to the deposition of QDs is observedwith light microscopy and electrical measurements as a global increase of Ca2+in the epithelial layers and a transient decrease in the electrical response. Theseobservations imply that the influx of calcium caused by the QD deposition is inducedby mechanical stressIn an additional ongoing study, the age determination of dried blood spotsare investigated with the usage of protein markers commonly found in the blood.Human serum (HS) is spiked with a marker of interest to mimic those of normallevels in adult human males. After which the HS is allowed to undergo an ageingprocess in a 96 well plate and further analysed in terms of the enzymatic activitywith commercially available kits. The preliminary test results show that there is ameasurable change of activity dependenton the utilised marker that may act as abasis for the age determination of dried blod spots

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2019. , p. 119
Series
TRITA-SCI-FOU ; 2019:42
Keywords [en]
Graphene, Quantum Dots, Blood, Forensics, Drugs
National Category
Natural Sciences Nano Technology
Research subject
Biological Physics
Identifiers
URN: urn:nbn:se:kth:diva-262750ISBN: 978-91-7873-307-1 (print)OAI: oai:DiVA.org:kth-262750DiVA, id: diva2:1362481
Presentation
2019-10-18, Pascal, Tomtebodavägen 23a, Solna, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Foundation for Strategic Research , Forskningsinstitutsdoktorand 2015
Note

Examinator: Professor Björn Önfelt

Available from: 2019-10-21 Created: 2019-10-20 Last updated: 2019-10-21Bibliographically approved
List of papers
1. Intrinsic blinking characteristics of single colloidal CdSe-CdS/ZnS core-multishell quantum dots
Open this publication in new window or tab >>Intrinsic blinking characteristics of single colloidal CdSe-CdS/ZnS core-multishell quantum dots
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2019 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 99, no 3, article id 035404Article in journal (Refereed) Published
Abstract [en]

Fluorescence blinking of single colloidal semiconductor quantum dots (QDs) has been extensively studied, and several sophisticated models have been proposed. In this work, we derive Heisenberg equations of motion to carefully study principal transition processes, i.e., photoexcitation, energy relaxation, impact ionization and Auger recombination, radiative and nonradiative recombinations, and tunneling between core states and surface states, of the electron-hole pair in single CdSe-CdS/ZnS core-multishell QDs and show that the on-state probability density distribution of the QD fluorescence obeys the random telegraph signal theory because of the random radiative recombination of the photoexcited electron-hole pair in the QD core, while the off-state probability density distribution obeys the inverse power law distribution due to the series of random walks of the photoexcited electron in the two-dimensional surface-state network after the electron tunnels from the QD core to the QD surface. These two different blinking characteristics of the single QD are resolved experimentally by properly adjusting the optical excitation power and the bin time.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2019
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-241317 (URN)10.1103/PhysRevB.99.035404 (DOI)000454766400012 ()2-s2.0-85059881217 (Scopus ID)
Note

QC 20190125

Available from: 2019-01-25 Created: 2019-01-25 Last updated: 2019-10-20Bibliographically approved
2. Chemical Sensors Generated on Wafer-Scale Epitaxial Graphene for Application to Front-Line Drug Detection
Open this publication in new window or tab >>Chemical Sensors Generated on Wafer-Scale Epitaxial Graphene for Application to Front-Line Drug Detection
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2019 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 19, no 10, article id 2214Article in journal (Refereed) Published
Abstract [en]

Generation of large areas of graphene possessing high quality and uniformity will be a critical factor if graphene-based devices/sensors are to be commercialized. In this work, epitaxial graphene on a 2" SiC wafer was used to fabricate sensors for the detection of illicit drugs (amphetamine or cocaine). The main target application is on-site forensic detection where there is a high demand for reliable and cost-efficient tools. The sensors were designed and processed with specially configured metal electrodes on the graphene surface by utilizing a series of anchors where the metal contacts are directly connected on the SiC substrate. This has been shown to improve adhesion of the electrodes and decrease the contact resistance. A microfluidic system was constructed to pump solutions over the defined graphene surface that could then act as a sensor area and react with the target drugs. Several prototypic systems were tested where non-covalent interactions were used to localize the sensing components (antibodies) within the measurement cell. The serendipitous discovery of a wavelength-dependent photoactivity for amphetamine and a range of its chemical analogs, however, limited the general application of these prototypic systems. The experimental results reveal that the drug molecules interact with the graphene in a molecule dependent manner based upon a balance of -stacking interaction of the phenyl ring with graphene (p-doping) and the donation of the amine nitrogens lone pair electrons into the *-system of graphene (n-doping).

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
epitaxial graphene, sensors, microfluidics, photoactivity, illicit drugs, forensics
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-255223 (URN)10.3390/s19102214 (DOI)000471014500001 ()31091664 (PubMedID)2-s2.0-85066874691 (Scopus ID)
Note

QC 20190903

Available from: 2019-09-03 Created: 2019-09-03 Last updated: 2019-10-20Bibliographically approved
3. Endocytic pathway of vascular cell adhesion molecule 1 in human umbilical vein endothelial cell identified in vitro by using functionalized nontoxic fluorescent quantum dots
Open this publication in new window or tab >>Endocytic pathway of vascular cell adhesion molecule 1 in human umbilical vein endothelial cell identified in vitro by using functionalized nontoxic fluorescent quantum dots
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2019 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 297, article id 126702Article in journal (Refereed) Published
Abstract [en]

Studies about vascular cell adhesion molecule 1 (VCAM1) in tumor growth, metastasis, and angiogenesis suggest that targeting VCAM1 expression is an attractive strategy for diagnosis and anti-tumor therapy. However, the endocytic pathway of VCAM1 in vascular cells has not been well characterized. In this study we visualize the endocytic pathway of tumor necrosis factor α (TNFα) induced VCAM1 in human umbilical vein endothelial cell (HUVEC) in vitro using 5-carboxyfluorescein labeled VCAM1 binding peptides and fluorescent water-dispersible 3-mercaptopropionic acid (3MPA)-coated CdSe-CdS/Cd0.5Zn0.5S/ZnS core–multishell nontoxic quantum dots (3MPA-QDs) functionalized with VCAM1 binding peptides. Clear key in vitro observations are as follows: (a) 3MPA-QDs functionalized with VCAM1 binding peptides, denoted as VQDs, adhered and aggregated cumulatively to cell membrane around 2 h after VQD deposition to cell culture medium and were found in lysosomes in TNFα-treated HUVECs approximately 24 h after VQD deposition; (b) VQDs remained in TNFα-treated HUVECs for the whole 16 days of the experimental observation period; (c) quite differently, 3MPA-QDs were endocytosed then exocytosed by HUVECs via endosomes in about 24–48 h after 3MPA-QD deposition. Our study suggests that VCAM1 molecules, initially expressed on cell membrane induced by TNFα treatment, are internalized into lysosomes. This provides a novel means to deliver materials to lysosomes such as enzyme replacement therapy. Moreover, our meticulous sensing methodology of devising fluorescent nontoxic QDs advances biosensing technique for studying cellular activities in vitro and in vivo.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Bionanosensors, Colloidal fluorescent quantum dot, Endosome, Human umbilical vein endothelial cell, Lysosome, Vascular cell adhesion molecule 1 (VCAM1)
National Category
Industrial Biotechnology
Research subject
Physics, Biological and Biomedical Physics
Identifiers
urn:nbn:se:kth:diva-262749 (URN)10.1016/j.snb.2019.126702 (DOI)000478562700041 ()2-s2.0-85067809943 (Scopus ID)
Note

QC 20191022

Available from: 2019-10-20 Created: 2019-10-20 Last updated: 2019-11-26Bibliographically approved
4. Quantum dots modulate intracellular Ca2+ level in lung epithelial cells
Open this publication in new window or tab >>Quantum dots modulate intracellular Ca2+ level in lung epithelial cells
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2017 (English)In: International Journal of Nanomedicine, ISSN 1176-9114, E-ISSN 1178-2013, Vol. 12, p. 2781-2792Article in journal (Refereed) Published
Abstract [en]

While adverse effects of nanoparticles on lung health have previously been proposed, few studies have addressed the direct effects of nanoparticle exposure on the airway epithelium. In this work, we examine the response of the pulmonary airway to nanoparticles by measuring intracellular Ca2+ concentration ([Ca2+](i)) in the Calu-3 epithelial layer stimulated by 3-mercaptopropionic-acid (3MPA) coated CdSe-CdS/ZnS core-multishell quantum dots (QDs). Simultaneous transient transepithelial electrical resistance (TEER) decrease and global [Ca2+](i) increase in Calu-3 epithelial layer, accompanied by cell displacements, contraction, and expansion, were observed under QD deposition. This suggests that a QD-induced global [Ca2+](i) increase in the Calu-3 epithelial layer caused the transient TEER decrease. The [Ca2+](i) increase was marked and rapid in the apical region, while [Ca2+](i) decreased in the basolateral region of the epithelial layer. TEER transient response and extracellular Ca2+ entry induced by QD deposition were completely inhibited in cells treated with stretched-activated (SA) inhibitor GdCl3 and store-operated calcium entry (SOCE) inhibitor BTP2 and in cells immersed in Ca2+-free medium. The voltage-gated calcium channel (VGCC) inhibitor nifedipine decreased, stabilized, and suppressed the TEER response, but did not affect the [Ca2+](i) increase, due to QD deposition. This demonstrates that the Ca2+ influx activated by QDs' mechanical stretch occurs through activation of both SA and SOCE channels. QD-induced [Ca2+](i) increase occurred in the Calu-3 epithelial layer after culturing for 15 days, while significant TEER drop only occurred after 23 days. This work provides a new perspective from which to study direct interactions between airway epithelium and nanoparticles and may help to reveal the pathologies of pulmonary disease.

Place, publisher, year, edition, pages
DOVE MEDICAL PRESS LTD, 2017
Keywords
Calu-3 epithelial layer, quantum dot, intracellular Ca2+ concentration [Ca2+](i), transepithelial electrical resistance, cell movement
National Category
Nano Technology Pharmaceutical Sciences
Identifiers
urn:nbn:se:kth:diva-206308 (URN)10.2147/IJN.S130136 (DOI)000398663200001 ()2-s2.0-85017256402 (Scopus ID)
Note

QC 20170505

Available from: 2017-05-05 Created: 2017-05-05 Last updated: 2019-10-20Bibliographically approved

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