Performance Analysis and Design of Position-Encoded Microsphere Arrays Using the Ziv-Zakai Bound

Xu, Xiaojun; Sarder, Pinaki; Kotagiri, Nalinikanth; Achilefu, Samuel; Nehorai, Arye

doi:10.1109/tnb.2012.2230116

Cited by 9 publications

(9 citation statements)

References 26 publications

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“…13,14 We have previously demonstrated controlled trapping of polystyrene microspheres and simultaneously applied advanced signal and image processing techniques to achieve a highly optimized device for performing fluoroimmunoassays. 15 Herein, we have implemented the biological protocol of the immunoassay to the device and tested its performance and sensitivity. The versatile and efficient conjugation and analysis used in this study creates a platform for high throughput screening of biological samples.…”

Section: Introductionmentioning

confidence: 99%

Antibody Quantum Dot Conjugates Developed via Copper-Free Click Chemistry for Rapid Analysis of Biological Samples Using a Microfluidic Microsphere Array System

Kotagiri

et al. 2014

Bioconjugate Chem.

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Antibody-based proteomics is an enabling technology that has significant implications for cancer biomarker discovery, diagnostic screening, prognostic and pharmacodynamic evaluation of disease state, and targeted therapeutics. Quantum dot based fluoro-immunoconjugates possess promising features towards realization of this goal such as high photostability, brightness and multispectral tunability. However, current strategies to generate such conjugates are riddled with complications such as improper orientation of antigen binding sites of the antibody, aggregation and stability issues. We report a facile yet effective strategy to conjugate anti epidermal growth factor receptor (EGFR) antibody to quantum dots using copper-free click reaction, and compared them to similar constructs prepared using traditional strategies such as succinimidyl-4-(N-maleimidomethyl) cyclohexane-1-carboxylate (SMCC) and biotin-streptavidin schemes. The Fc and Fab regions of the conjugates retain their binding potential, compared to those generated through the traditional schemes. We further applied the conjugates in testing a novel microsphere array device designed to carry out sensitive detection of cancer biomarkers through fluoroimmunoassays. Using purified EGFR, we determined the limit of detection of the microscopy centric system to be 12.5 ng/ml. The biological assay, in silico, was successfully tested and validated by using tumor cell lysates, as well as human serum from breast cancer patients and the results were compared to normal serum. A pattern consistent with established clinical data was observed, which further validates the effectiveness of the developed conjugates and its successful implementation both in vitro as well as in silico fluoroimmunoassays. The results suggest the potential development of a high throughput in silico paradigm for predicting the class of patient cancer based on EGFR expression levels relative to normal reference levels in blood.

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Section: Introductionmentioning

confidence: 99%

Antibody Quantum Dot Conjugates Developed via Copper-Free Click Chemistry for Rapid Analysis of Biological Samples Using a Microfluidic Microsphere Array System

Kotagiri

et al. 2014

Bioconjugate Chem.

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“…6,7,36 We will use on-chip micromechanical valves and isolated microfluidic chambers for simultaneously trapping the microspheres at predetermined positions and detecting targets of diverse types, and thus achieve a multifunctional platform. We plan to conduct biomedical experiments on this platform.…”

Section: Discussionmentioning

confidence: 99%

Optimization of microfluidic microsphere-trap arrays

Sarder

et al. 2013

Biomicrofluidics

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Microarray devices are powerful for detecting and analyzing biological targets. However, the potential of these devices may not be fully realized due to the lack of optimization of their design and implementation. In this work, we consider a microsphere-trap array device by employing microfluidic techniques and a hydrodynamic trapping mechanism. We design a novel geometric structure of the trap array in the device, and develop a comprehensive and robust framework to optimize the values of the geometric parameters to maximize the microsphere arrays' packing density. We also simultaneously optimize multiple criteria, such as efficiently immobilizing a single microsphere in each trap, effectively eliminating fluidic errors such as channel clogging and multiple microspheres in a single trap, minimizing errors in subsequent imaging experiments, and easily recovering targets. We use finite element simulations to validate the trapping mechanism of the device, and to study the effects of the optimization geometric parameters. We further perform microsphere-trapping experiments using the optimized device and a device with randomly selected geometric parameters, which we denote as the un-optimized device. These experiments demonstrate easy control of the transportation and manipulation of the microspheres in the optimized device. They also show that the optimized device greatly outperforms the un-optimized device by increasing the packing density by a factor of two, improving the microsphere trapping efficiency from 58% to 99%, and reducing fluidic errors from 48% to a negligible level (less than 1%). The optimization framework lays the foundation for the future goal of developing a modular, reliable, efficient, and inexpensive lab-on-a-chip system.

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“…[1][2][3][4] These arrays have great potential such as the independent, quantitative, and simultaneous assay of multiple types of targets in small volumes of material and collection of statistically rigorous data from numerous microspheres for each type of target. In the microsphere arrays, the microspheres are functionalized with ligands on their surface that are specific to certain targets.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous detection of multiple biological targets using optimized microfluidic microsphere-trap arrays

Sarder

et al. 2014

J. Micro/Nanolith. MEMS MOEMS

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We propose an analytical framework to build a microfluidic microsphere-trap array device that enables simultaneous, efficient, and accurate screening of multiple biological targets in a single microfluidic channel. By optimizing the traps' geometric parameters, the trap arrays in the channel of the device can immobilize microspheres of different sizes at different regions, obeying hydrodynamically engineered trapping mechanism. Different biomolecules can be captured by the ligands on the surfaces of microspheres of different sizes. They are thus detected according to the microspheres' positions (position encoding), which simplifies screening and avoids target identification errors. To demonstrate the proposition, we build a device for simultaneous detection of two target types by trapping microspheres of two sizes. We evaluate the device performance using finite element fluidic dynamics simulations and microsphere-trapping experiments. These results validate that the device efficiently achieves position encoding of the two-sized microspheres with few fluidic errors, providing the promise to utilize our framework to build devices for simultaneous detection of more targets. We also envision utilizing the device to separate, sort, or enumerate cells, such as circulating tumor cells and blood cells, based on cell size and deformability. Therefore, the device is promising to become a cost-effective and point-of-care miniaturized disease diagnostic tool.

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Performance Analysis and Design of Position-Encoded Microsphere Arrays Using the Ziv-Zakai Bound

Cited by 9 publications

References 26 publications

Antibody Quantum Dot Conjugates Developed via Copper-Free Click Chemistry for Rapid Analysis of Biological Samples Using a Microfluidic Microsphere Array System

Antibody Quantum Dot Conjugates Developed via Copper-Free Click Chemistry for Rapid Analysis of Biological Samples Using a Microfluidic Microsphere Array System

Optimization of microfluidic microsphere-trap arrays

Simultaneous detection of multiple biological targets using optimized microfluidic microsphere-trap arrays

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