Thermal Mechanical Stretching to Imprint Pores Morphology of Nitrocellulose Membrane for Immuno-sensing Application

Performance of membrane such as the lateral flow wicking time and protein binding ability are important to generate consistent results for diagnostics purposes. Different diagnostic kit need different surface properties of membrane, structures and dimension. This work evaluates the feasibility of controlling membrane pores morphology through thermal-mechanical stretching. Results shows that membrane fabricated using longer nitrocellulose (NC) polymer chain length produced smaller pores with lower porosity (56%). Thus, it took longer time of 32s to migrate the testing liquid along the membrane strip. By having higher membrane’s porosity (72.3%), the membrane synthesized using shorter NC chain length exhibited faster wicking time, which is 3 times faster (wicking time of 8s) than that of the membrane produced with longer NC chain length. In terms of the thermal-mechanical stretching effects, the stretched membranes (both uniaxial and biaxial directions) had demonstrated improved immunoassay performances compared to the unstretched membrane. Specifically, uniaxial stretching is preferable than biaxial stretching configuration, due to the great improvement of lateral wicking time (22% faster) without jeopardize the membrane protein binding capacity (only 1.7% decrement), in relative to the unstretched membrane. This study provides some interesting insight on the physical membrane modification to provide better performance in immunoassay applications.

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Impact of Silanization Parameters and Antibody Immobilization Strategy on Binding Capacity of Photonic Ring Resonators

Sensors ◽

10.3390/s20113163 ◽

2020 ◽

Vol 20 (11) ◽

pp. 3163

Author(s):

Nina Bjørk Arnfinnsdottir ◽

Cole A. Chapman ◽

Ryan C. Bailey ◽

Astrid Aksnes ◽

Bjørn Torger Stokke

Keyword(s):

Protein Binding ◽

Ring Resonator ◽

Silicon Oxide ◽

Binding Capacity ◽

Ring Resonators ◽

Widespread Application ◽

Reactive Protein ◽

Oxide Substrates ◽

Protein Binding Capacity ◽

Selection Of

Ring resonator-based biosensors have found widespread application as the transducing principle in “lab-on-a-chip” platforms due to their sensitivity, small size and support for multiplexed sensing. Their sensitivity is, however, not inherently selective towards biomarkers, and surface functionalization of the sensors is key in transforming the sensitivity to be specific for a particular biomarker. There is currently no consensus on process parameters for optimized functionalization of these sensors. Moreover, the procedures are typically optimized on flat silicon oxide substrates as test systems prior to applying the procedure to the actual sensor. Here we present what is, to our knowledge, the first comparison of optimization of silanization on flat silicon oxide substrates to results of protein capture on sensors where all parameters of two conjugation protocols are tested on both platforms. The conjugation protocols differed in the chosen silanization solvents and protein immobilization strategy. The data show that selection of acetic acid as the solvent in the silanization step generally yields a higher protein binding capacity for C-reactive protein (CRP) onto anti-CRP functionalized ring resonator sensors than using ethanol as the solvent. Furthermore, using the BS3 linker resulted in more consistent protein binding capacity across the silanization parameters tested. Overall, the data indicate that selection of parameters in the silanization and immobilization protocols harbor potential for improved biosensor binding capacity and should therefore be included as an essential part of the biosensor development process.

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