Micro-patterned molecularly imprinted polymer structures on functionalized diamond-coated substrates for testosterone detection

Abstract

Molecularly imprinted polymers (MIPs) can selectively bind target molecules and can therefore be advantageously used as a low-cost and robust alternative to replace fragile and expensive natural receptors. Yet, one major challenge in using MIPs for sensor development is the lack of simple and cost-effective techniques that allow firm fixation as well as controllable and consistent receptor material distribution on the sensor substrate. In this work, a convenient method is presented wherein microfluidic systems in conjunction with in situ photo-polymerization on functionalized diamond substrates are used. This novel strategy is simple, efficient, low-cost and less time consuming. Moreover, the approach ensures a tunable and consistent MIP material amount and distribution between different sensor substrates and thus a controllable active sensing surface. The obtained patterned MIP structures are successfully tested as a selective sensor platform to detect physiological concentrations of the hormone disruptor testosterone in buffer, urine and saliva using electrochemical impedance spectroscopy. The highest added testosterone concentration (500 nM) in buffer resulted in an impedance signal of 10.03 ± 0.19% and the lowest concentration (0.5 nM) led to a measurable signal of 1.8 ± 0.15% for the MIPs. With a detection limit of 0.5 nM, the MIP signals exhibited good linearity between a 0.5 nM and 20 nM concentration range. Apart from the excellent and selective recognition offered by these MIP structures, they are also stable during and after the dynamic sensor measurements. Additionally, the MIPs can be easily regenerated by a simple washing procedure and are successfully tested for their reusability.

Self-assembly Synthesis of Molecularly Imprinted Polymers for the Ultrasensitive Electrochemical Determination of Testosterone

“…Figure 5a also shows that the useful linear dynamic range is 0.1 to 100 pg/mL for testosterone, with the signal beginning to saturate at the higher concentration. We compare these results to other testosterone detection methods: micro-patterned MIPs on functionalized diamond-coated substrates were reported to show linearity from 0.5 to 20 nM testosterone [29]; reflectance spectra of TIECPs films showed a shift of the Bragg diffraction peak that correlated with testosterone concentration in the range 5-100 ng/mL [15]. Thus, the electrochemical approach presented here is highly sensitive.…”

Self-assembly Synthesis of Molecularly Imprinted Polymers for the Ultrasensitive Electrochemical Determination of Testosterone

“…The sensitivity concentration with linear dynamic range is 0.1 to 100 pg/mL for testosterone. Moreover, micro-patterned MIPs on functionalized diamond-coated substrates for testosterone was reported with linearity between a 0.5 to 20 nM [44], and the reflectance spectra of MIPs films showed a shift of the Bragg diffraction peak that correlated with testosterone concentration was in the 5-100 ng/mL [16]. The eletrodes of TIPs were highly sensitive.…”

Current methods for stress marker detection in saliva

“…In general, IA are susceptible to cross-reactivity dependent on the selectivity of antibodies used therein. Molecularly imprinted polymers (MIPs) are recently studied as alternatives and used in assays to overcome the economic downsides of antibody-based assays [ 43 ]. Similarly, bio- or chemiluminescent assays may serve as alternatives [ [44] , [45] , [46] , [47] , [48] , [49] ].…”

“…Kellens et al used a microfluidic system combined with an in situ photo-polymerization on functionalized diamond substrates to obtain a controlled and consistent distribution of micro-patterned MIPs on the sensor substrate. So, they realized a selective sensor platform for testosterone [ 43 ].…”

“…into a tube Salivette® Salivette® 3 pg/mL 43.2 pg/mL (LLOQ) > 0.3 ng/mL 4 pg/mL 4.9 pg/mL LLE, Simultaneous detection of melatonin and cortisol DLLME, positive mode Simultaneous detection of 15 other steroids Derivatization with HMP, simultaneous detection of DHEA SPE, quadrupole linear ion trap, simultaneous quantitation of 17-OHP, aldosterone, AED, cortisol, cortisone, DHEA-S, estradiol, progesterone, and testosterone MALDI-MS [ 114 , 122 ] Spitting directly into a tube 1.7 μg/mL Simultaneous detection of progesterone, cortisone, hydrocortisone. MIP-sensor [ 43 , 122 ] n.s. 0.14 ng/mL on Functionalized Diamond-Coated Substrates Multimode sensors [ 43 , 123 ] n.s.…”