45 research outputs found
Towards Microfluidic Design Automation
Microfluidic chips, lab-on-a-chip devices that have channels transporting liquids instead of wires carrying electrons, have attracted considerable attention recently from the bio-medical industry because of their application in testing assay and large-scale chemical reaction automation. These chips promise dramatic reduction in the cost of large-scale reactions and bio-chemical sensors. Just like in traditional chip design, there is an acute need for automation tools that can assist with design, testing and verification of microfluidics chips. We propose a design methodology and tool to design microfluidic chips based on SMT solvers. The design of these chips is expressed using the language of partial differential equations (PDEs) and non-linear multi-variate polynomials over the reals. We convert such designs into SMT2 format through appropriate approximations, and invoke Z3 and dReal solver on them. Through our experiments we show that using SMT solvers is a not only a viable strategy to address the microfluidics design problem, but likely will be key component of any future development environment.
In addition to analysis of Microfluidic Chip design, we discuss the new area of Microhydraulics; a new technology being developed for the purposes of macking dynamic molds and dies for manufacturing. By contrast, Microhydraulics is more concerned on creating designs that will satisfy the dynamic requirements of manufacturers, as opposed to microfludics which is more concerned about the chemical reactions taking place in a chip. We develop the background of the technology as well as the models required for SMT solvers such as Z3 and dReal to solve them
G-Quadruplex Aptamer Beacon for Detection of Prostate Cancer Biomarker
The prostate is the major male reproductive gland involved in male fertility and plays
an important role in triggering of molecular pathways relevant to fertility success.
Unfortunately, in Portugal prostate cancer is the most common cancer type among
men, being asymptomatic in earlier stages. Thus, is important early detection of
disease.
NCL is a multifunctional protein involved in multiple biological processes under both
physiological and pathological processes and can have several cellular localizations.
Cell surface protein overexpression was found restricted to cancer cells, namely in
prostate cancer cells. Thus, we can consider NCL as a potential biomarker for cancer
diagnosis and a target for cancer treatment. The AS1411 is an aptamer capable to
recognise and binds specifically NCL and have a therapeutic effect on cancer cells
through of induction of antiproliferative activity. Beyond its therapeutic use, AS1411
can be used in imaging and diagnostic, particularly on aptasensors development. One
of the most relevant characteristics of this aptamer is the ability to fold in a G4
conformation, a secondary structure of nucleic acids. G4 structure confers stabilization
to sequence and availability to bind NCL.
Thus, in this work is presented the first approach of use AS1411 aptamer to prostate
cancer diagnosis, namely through the design of molecular beacon (MB) designated by
AS1411N5. Initially, biophysical characterization of AS1411-N5 was done by circular
dichroism, nuclear magnetic resonance or fluorometric spectroscopies. Additionally, it
was performed microfluidic experiments, to detect NCL using AS1411-N5 in biological
samples.
The results demonstrated that the proposed AS1411-N5 adopt a G4 structure and it is
capable to bind with specificity and selectivity NCL, even in plasma of human patients
with prostate cancer.A próstata é a maior glândula reprodutiva masculina e tem um papel importante nas
vias moleculares relevantes para o sucesso da fertilização. Infelizmente, em Portugal o
cancro da próstata é o cancro mais comum entre os homens, sendo assintomático em
estadios iniciais. Assim é imperativo a deteção precoce da doença.
A nucleolina (NCL) é uma proteína multifuncional envolvida em múltiplos processos
biológicos sob condições fisiológicas e patológicas, podendo ter várias localizações
celulares. A sobre-expressão da proteína na superfície das células é apenas encontrada
em células cancerosas, nomeadamente as do cancro da próstata. Assim a NCL pode ser
considerada como um potencial biomarcador para o diagnóstico e tratamento do
cancro da próstata. O AS411 é um aptamero capaz de reconhecer e ligar especificamente
a esta proteína, e de ter um efeito terapêutico nas células cancerosas ao induzir
atividade antiproliferativa. Além do uso terapêutico, a sequência pode ser utilizada na
imagiologia e diagnóstico, particularmente através do desenvolvimento de
aptasensores. Uma das características mais relevantes do aptamero AS1411 é a
capacidade de adotar a configuração de G-quadruplex (G4), uma estrutura secundária
dos ácidos nucleicos. As estruturas G4 conferem estabilização à sequência e capacidade
de ligar à NCL quando adota esta estrutura.
Assim, neste trabalho é apresentada uma primeira abordagem do uso do AS1411 no
diagnóstico do cancro da próstata, nomeadamente através da construção de uma sonda
a partir da sequência deste aptamero designado por AS1411N5. Inicialmente foi
efetuada a caracterização biofísica do AS1411-N5 a nível da estrutura e interação com o
alvo, recorrendo às espectroscopias dicroísmo circular e ressonância magnética
nuclear, e ensaios fluorométricos. Adicionalmente foram efetuadas experiências de
microfluídica, para o uso do AS1411N5 como sonda de deteção da NCL.
Estes resultados demonstraram, que o AS1411-N5adota a estrutura G4 e é capaz de ligar
especificamente e com seletividade com a NCL, mesmo em amostras biológicas
Advances in Optofluidics
Optofluidics a niche research field that integrates optics with microfluidics. It started with elegant demonstrations of the passive interaction of light and liquid media such as liquid waveguides and liquid tunable lenses. Recently, the optofluidics continues the advance in liquid-based optical devices/systems. In addition, it has expanded rapidly into many other fields that involve lightwave (or photon) and liquid media. This Special Issue invites review articles (only review articles) that update the latest progress of the optofluidics in various aspects, such as new functional devices, new integrated systems, new fabrication techniques, new applications, etc. It covers, but is not limited to, topics such as micro-optics in liquid media, optofluidic sensors, integrated micro-optical systems, displays, optofluidics-on-fibers, optofluidic manipulation, energy and environmental applciations, and so on
Particles Separation in Microfluidic Devices, Volume II
Microfluidic platforms are increasingly being used for separating a wide variety of particles based on their physical and chemical properties. In the past two decades, many practical applications have been found in chemical and biological sciences, including single cell analysis, clinical diagnostics, regenerative medicine, nanomaterials synthesis, environmental monitoring, etc. In this Special Issue, we invited contributions to report state-of-the-art developments in the fields of micro- and nanofluidic separation, fractionation, sorting, and purification of all classes of particles, including, but not limited to, active devices using electric, magnetic, optical, and acoustic forces; passive devices using geometries and hydrodynamic effects at the micro/nanoscale; confined and open platforms; label-based and label-free technology; and separation of bioparticles (including blood cells), circulating tumor cells, live/dead cells, exosomes, DNA, and non-bioparticles, including polymeric or inorganic micro- and nanoparticles, droplets, bubbles, etc. Practical devices that demonstrate capabilities to solve real-world problems were of particular interest
Miniaturizing High Throughput Droplet Assays For Ultrasensitive Molecular Detection On A Portable Platform
Digital droplet assays – in which biological samples are compartmentalized into millions of femtoliter-volume droplets and interrogated individually – have generated enormous enthusiasm for their ability to detect biomarkers with single-molecule sensitivity. These assays have untapped potential for point-of-care diagnostics but are mainly confined to laboratory settings due to the instrumentation necessary to serially generate, control, and measure millions of compartments. To address this challenge, we developed an optofluidic platform that miniaturizes digital assays into a mobile format by parallelizing their operation. This technology has three key innovations: 1. the integration and parallel operation of hundred droplet generators onto a single chip that operates \u3e100x faster than a single droplet generator. 2. the fluorescence detection of droplets at \u3e100x faster than conventional in-flow detection using time-domain encoded mobile-phone imaging, and 3. the integration of on-chip delay lines and sample processing to allow serum-to-answer device operation. By using this time-domain modulation with cloud computing, we overcome the low framerate of digital imaging, and achieve throughputs of one million droplets per second. To demonstrate the power of this approach, we performed a duplex digital enzyme-linked immunosorbent assay (ELISA) in serum to show a 1000x improvement over standard ELISA and matching that of the existing laboratory-based gold standard digital ELISA system. This work has broad potential for ultrasensitive, highly multiplexed detection, in a mobile format. Building on our initial demonstration, we explored the following: (i) we demonstrated that the platform can be extended to \u3e100x multiplexing by using time-domain encoded light sources to detect color-coded beads that each correspond to a unique assay, (ii) we demonstrated that the platform can be extended to the detection of nucleic acid by implementing polymerase chain reaction, and (iii) we demonstrated that sensitivity can be improved with a nanoparticle-enhanced ELISA. Clinical applications can be expanded to measure numerous biomarkers simultaneously such as surface markers, proteins, and nucleic acids. Ultimately, by building a robust device, suitable for low-cost implementation with ultrasensitive capabilities, this platform can be used as a tool to quantify numerous medical conditions and help physicians choose optimal treatment strategies to enable personalized medicine in a cost-effective manner
Development of microcantilever sensors for cell studies
Micro- and nano- electromechanical devices such as microcantilevers have paved the
way for a large variety of new possibilities, such as the rapid diagnosis of diseases and a
high throughput platform for drug discovery. Conventional cell assay methods rely on
the addition of reagents, disrupting the measurement, therefore providing only the
endpoint data of the cell growth experiment. In addition, these methods are typically
slow to provide results and time and cost consuming. Therefore, microcantilever sensors
are a great platform to conduct cell culturing experiments for cell culture, viability,
proliferation, and cytotoxicity monitoring, providing advantages such as being able to
monitor cell kinetics in real time without requiring external reagents, in addition to
being low cost and fast, which conventional cell assay methods are unable to provide.
This work aims to develop and test different types of microcantilever biosensors for the
detection and monitoring of cell proliferation. This approach will overcome many of the
current challenges facing microcantilever biosensors, including but not limited to
achieving characteristics such as being low cost, rapid, easy to use, highly sensitive,
label-free, multiplexed arrays, etc.
Microcantilever sensor platforms utilizing both a single and scanning optical beam
detection methods were developed and incorporated aspects such as temperature control,
calibration, and readout schemes. Arrays of up to 16 or 32 microcantilever sensors can
be simultaneously measured with integrated microfluidic channels. The effectiveness of
these cantilever platforms are demonstrated through multiple studies, including
examples of growth induced bending of polyimide cantilevers for simple real-time yeast
cell measurements and a microcantilever array for rapid, sensitive, and real-time
measurement of nanomaterial toxicity on the C3A human liver cell line. In addition,
other techniques for microcantilever arrays and microfluidics will be presented along
with demonstrations for the ability for stem cell growth monitoring and pathogen
detection
Concentration of Phosphorylated Proteins Using Modified PMMA Microanalytical Devices
This work describes the application of PMMA-based microanalytical devices for the affinity-type preconcentration of posttranslational modified proteins (PTMs). The choice of poly(methyl methacrylate), PMMA, is based on its biocompatibility, its functional methyl ester group for potential modification, and its extensive applications to create biological microelectromechanical systems (BioMEMS). Developing methodologies for preconcentration of PTMs is important for cancer diagnosis due to PTMs’ influence in the regulatory mechanism underlying the early stage of apoptosis or regulated cell death. Towards this goal, nitroavidin which can reversibly binds to biotin (and biotinylated proteins), was prepared using reported procedure and was characterized using several techniques such as UV-Visible spectroscopy, sodium dodecyl sulfate−polyacrylamide gel electrophoresis (SDS-PAGE), enzyme-linked immunosorbent assay (ELISA), and Western blot experiments. UV-Visible spectroscopy experiments showed reversible binding of nitroavidin towards the biotin analogue 2-(4’-hydroxyazobenzene) benzoic acid, HABA. From mass spectrometry studies, nitrotyrosine was confirmed to be present in the prepared nitroavidin through an observed photoinduced chemical fragmentation. SPR experiments revealed decrease in binding of nitroavidin towards biotinylated proteins (the equilibrium dissociation constant obtained for the biotin−nitroavidin interactions is higher, KD = 4 x 10–6 M, than biotin-avidin interactions, KD = 1 x 10–13 M). Also, there was an observed efficiency of 23 ± 1% for the capture process of biotinylated proteins on nitroavidin−functionalized PMMA open microchannels, while high capture efficiency (96 ± 0.5%) for bound biotinylated proteins were observed on PMMA microchannels with fabricated microposts. To further improve the efficiency of capture and release processes, PMMA ultra-high-aspect-ratio nanostructures (UHRANs) were employed to provide higher surface-to-volume reactor bed. These PMMA UHRANs were fabricated in our group using previously reported template-based anodization. PMMA nanopillars or nanoposts were developed using photopolymerization between the methyl methacrylate monomer and initiator, while PMMA nanotubes were fabricated using PMMA melt. These nanostructures were UV-modified to promote formation of surface carboxylic acids (pendant −COOH). The confirmation of surface –COOH functionalization on these surfaces was achieved using different surface labeling techniques such as thallium (I) ethoxide and sulfosuccinimidyl-4-o-(4,4-dimethoxytrityl) butyrate (sulfo-SDTB) and were determined using several techniques such as confocal fluorescence microscopy, UV-Visible spectroscopy, AFM, SEM, and XPS
Micro/nanofluidic and lab-on-a-chip devices for biomedical applications
Micro/Nanofluidic and lab-on-a-chip devices have been increasingly used in biomedical
research [1]. Because of their adaptability, feasibility, and cost-efficiency, these devices
can revolutionize the future of preclinical technologies. Furthermore, they allow insights
into the performance and toxic effects of responsive drug delivery nanocarriers to be
obtained, which consequently allow the shortcomings of two/three-dimensional static
cultures and animal testing to be overcome and help to reduce drug development costs and
time [2–4]. With the constant advancements in biomedical technology, the development of
enhanced microfluidic devices has accelerated, and numerous models have been reported.
Given the multidisciplinary of this Special Issue (SI), papers on different subjects
were published making a total of 14 contributions, 10 original research papers, and
4 review papers. The review paper of Ko et al. [1] provides a comprehensive overview
of the significant advancements in engineered organ-on-a-chip research in a general way
while in the review presented by Kanabekova and colleagues [2], a thorough analysis
of microphysiological platforms used for modeling liver diseases can be found. To get
a summary of the numerical models of microfluidic organ-on-a-chip devices developed in
recent years, the review presented by Carvalho et al. [5] can be read. On the other hand,
Maia et al. [6] report a systematic review of the diagnosis methods developed for COVID-19,
providing an overview of the advancements made since the start of the pandemic.
In the following, a brief summary of the research papers published in this SI will be presented,
with organs-on-a-chip, microfluidic devices for detection, and device optimization
having been identified as the main topics.info:eu-repo/semantics/publishedVersio
Femtosecond Laser Nanomachining and Applications to Micro/Nanofluidics for Single Cell Analysis.
Femtosecond laser machining has huge potential to impact micro/nanofluidics with its ability to arbitrarily abricate 3-dimensional geometries with feature sizes down
to nanometer scales. Because cleanroom facilities, multilayer configurations, and glass bonding are not necessary to achieve 3-dimensional subsurface nanofeatures in glass, current planar lithography-etch-bond processes are easily combined with femtosecond laser machining; a hybrid machining based on these two methods constitutes a promising fabrication method for next generation microchip processes. The major challenge facing fs laser machining is that increasing the length of subsurface capillaries is very difficult; the normalized length (length/diameter) had
previously been limited to 50. In this dissertation, a new phenomenon, acoustic nodeformation, is shown to be the major barrier to increasing capillary length, and a theoretical model for node formation is established. Based on the node equation, degassed water, which is introduced to the ablation site to assist machining, is found to substantially overcome node formation. Thus, a novel degassed-water-assisted fs laser machining process is developed, improving the normalized length of submicron-scale capillaries to longer than 1000. Nano-capillary electrophoresis (nCE) is demonstrated, initiating a submicronscale separation regime with millisecond-fast separations and 1 femtoliter injection volumes (1000 times smaller than a single cell volume). Also, the current-controlled dielectric breakdown is found to convert a thin glass wall to an electrode, which is the core part in the nCE device zero-flow sample loader. This phenomenon can be further exploited in many novel micro/nanofluidic modules such as electrokinetic pumps, nanosensors, and nanoactuators with freedom to directly embed these modules in glass chips. These new micro/nanofluidic devices and modules will contribute to many novel biotechnology investigations, including single cell proteomics, cell characterization, DNA analysis, electrophysiology, and biological assays.Ph.D.Mechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/58515/1/toshlee_1.pd
Studies on high power ultrasonic microembossing and organic light emitting diodes (OLEDs) for the creation of lab-on-CD devices for sensor related applications
This study demonstrates the application of High Power Ultrasonic Microembossing Technology (HPUMT) in producing microfeatures on polymer substrates. The work reviews a novel method of obtaining flash free and precise microfeatures by manipulating the material density through microcellular foaming. The microfeatures created on the polymer substrates were further characterized by analyzing the feature depth with respect to the critical ultrasonic embossing operating parameters such as embossing heating times (s), embossing amplitude (ym) at a constant embossing trigger force (N). An experiment design was constructed and performed to characterize the parameters on foamed and unfoamed (or regular) versions of polystyrene (PS) and polypropylene (PP) sample materials. Results indicated feature depth was proportional to heating times, amplitude and force. It was also seen the maximum depth was achieved in the shortest cycle times with higher amplitudes and forces of operation.
HPUMT was further studied to create functional network of microchannels functioned as reservoirs, reaction chamber and burst or gate valves to form a centrifugal biosensing platform that is also referred to as a lab-on-CD or a bio-CD device. The surface energy of the polymer substrates was increased to enable fluid flow by using a surfactant based organic coating to facilitate hydrophilicity. Using an organic light emitting diode (OLEDs) as an electroluminescence source provided luminescence decay results in good agreement with stern-volmer relationship. The functionality of the OLED-coupled lab-on-CD device was further tested in measuring unknown concentrations of a particular analyte in corn slurry sample which contained numerous contaminants. Combinatorial multianalyte sensing was also made possible on a single bio-CD using a four photodetector (PD) quad preamp disk sensor