A chelating-bond breaking and re-linking technique for rapid re-immobilization of immune micro-sensors

Abstract

With high sensitivity and specificity to antigen, immune micro-sensors can be used in rapid detection of pathogenic microbial. This study proposes and develops a method for rapidly regeneration of antibody on a resonant micro-cantilever sensor. A nitrilotriacetic acid (NTA) derivative is synthesized with cystine and bromoacetic acid, then added with 2-mercaptoethanol to prepare a mixed self-assembled monolayer (SAM) on Au (111) surface of the cantilever. Ni²⁺ ions are thereafter chelated on the mixed SAM to form a breakable and re-linkable chelating-bond layer. Repeatable cycles of antibody immobilization and erasing are experimentally validated with a detectable marker of synthesized biotinylated poly peptides harboring six histidine residues (named as His-Bio). Two distinguished pathogenic microbial, Escherichia. coli O157:H7 and Bacillus Anthracis, are detected with the rapidly regenerated sensor. The E. coli O157:H7 sensor exhibits a three-time repeated detection to the 10³ CFU/ml concentration microbial. Then, an E. coli O157:H7 sensor is eluted with Tris-HCl (20 mM Tris, 150 mM NaCl, 0.1% Tween 20, pH = 3.0) and rapidly reconstructed into a B. Anthracis sensor by changing the re-immobilized antibody. The cantilever sensor no longer responses to E. coli O157:H7 even in a high concentration of 10⁷ CFU/ml. In contrast, the sensor is experimentally confirmed being resoluble to low concentration B. Anthracis at 10³ spores/ml level. The proposed fast regeneration method is promising in repeatedly or multi-target detection applications of micro/nano immune-sensors, e.g. the resonant micro-cantilevers.

Resonant-Gravimetric Identification of Competitive Adsorption of Environmental Molecules

“…38 By previously implementing the calibration experiment, where the microbeads with known mass were loaded on the cantilever for sensing, S = 1.5 Hz/pg has been obtained. 39 According to the experimentally achieved lower than 0.5 Hz noise floor of the frequency signal, 40 the mass detection resolution of the cantilever is finer than 1 pg in atmospheric ambience. Thanks to the precise MEMS (microelectromechanical systems) technology for batch fabrication of the cantilevers, the mass sensitivity of the batch-fabricated cantilevers is quite uniform.…”

“…Due to the adsorbed gas-molecule mass (Δ m ) being much smaller than that of the silicon cantilever ( m 0 ), the real-time-recorded frequency-shift signal can be accurately proportional to Δ m , i.e., Δ f / f 0 = 0.5Δ m / m 0 , and the mass sensitivity is defined as S = Δ f /Δ m . By previously implementing the calibration experiment, where the microbeads with known mass were loaded on the cantilever for sensing, S = 1.5 Hz/pg has been obtained . According to the experimentally achieved lower than 0.5 Hz noise floor of the frequency signal, the mass detection resolution of the cantilever is finer than 1 pg in atmospheric ambience.…”

A wireless bio-sensing microfluidic chip based on resonating ‘μ-divers’

“…Besides the advantage of large vibrating amplitude and high resonance quality factor (Q value), the ME resonant sensor features a unique nature of non-contact wireless excitation/sensing. This wireless sensing device is in contrast to conventional surface-acoustic-wave (SAW) resonators, 21,22 quartz-crystal-microbalance (QCM) sensors [23][24][25] or micro-cantilever sensors, [26][27][28] where direct electrical interconnection is always needed for resonance excitation and sensing signal readout.…”

Microgravimetric Analysis Method for Activation-Energy Extraction from Trace-Amount Molecule Adsorption

“…After two curves (at T 1 and T 2 , respectively) for the time-domain sorption process are obtained, the Langmuir sorption equilibrium constant K and the total active-site number N in the material sample can be calculated according to the known mass sensitivity of the resonant cantilever. Mass sensitivity S = 1.5 Hz/pg of our lab-made cantilevers has been calibrated by using commercial microbeads with known mass . Thanks to highly reproducible MEMS fabrication technologies, the fabricated silicon integrated cantilevers in one batch feature highly uniform sensitivity.…”

“…Mass sensitivity S = 1.5 Hz/pg of our lab-made cantilevers has been calibrated by using commercial microbeads with known mass. 30 Thanks to highly reproducible MEMS fabrication technologies, the fabricated silicon integrated cantilevers in one batch feature highly uniform sensitivity. For a certain gas concentration (i.e., certain partial pressure p), the adsorption rate at the initial adsorbing stage can be represented by the slope of the corresponding frequency-shift curve, that is, df/dt = k a pN.…”