Label-free detection of C-Reactive protein using bioresponsive hydrogel-based surface relief diffraction gratings

[EN] Responsive hydrogel-based surface relief gratings have demonstrated great performances as transducers in optical sensing. However, novel and smart designs of hydrogels are needed for the appropriate detection of analytes and biomolecules since the existing materials are very limited to specific molecules. In this work, a biosensing system based on surface relief gratings made of bioresponsive hydrogels has been developed. In particular, the hydrogel contains phosphocholine moieties to specifically recognize C-Reactive protein (CRP). The CRP-Sensing hydrogel capacity to selectively detect CRP was fully demonstrated. Using Direct Laser Interference Patterning, micro-gratings were created on CRP-Sensing hydrogel substrates and applied for the label-free sensing of CRP using a simple laser-based homemade optical setup. Limits of detection (LOD) and quantification (LOQ) in human serum dilutions of 1.07 and 8.92 mg L-1, respectively, were reached. These results demonstrate that the biosensing system allows the selective label-free detection of CRP within concentration ranges around those related to risks of cardiovascular diseases and sepsis. Besides, amplification strategies have been carried out improving the sensitivity, widening the linear range, and reaching better LOD and LOQ (0.30 mg L-1 and 4.36 mg L-1). Finally, all the approaches were tested for the quantification of CRP in certified human serum with recoveries of around 100%. This work was financially supported by the E.U. FEDER, the Spanish Ministry of Economy and Competitiveness MINECO (BiHolog-CTQ2016- 75749-R and AdBiHol-PID2019-110713RB-I00) and Generalitat Valenciana (PROMETEO/2020/094). M. I. Lucío acknowledges MINECO for her Juan de la Cierva Formacion and Incorporacion grants (FJCI-2016-29593, IJC 2018-035355-I). The authors acknowledge the assistance and advice of the Electron Microscopy Service of the Universitat Politècnica de València. Lucío, MI.; Hernández-Montoto, A.; Fernández-Sánchez, ME.; Alamri, S.; Kunze, T.; Bañuls Polo, M.; Maquieira Catala, Á. (2021). Label-free detection of C-Reactive protein using bioresponsive hydrogel-based surface relief diffraction gratings. Biosensors and Bioelectronics. 193:1-10. https://doi.org/10.1016/j.bios.2021.113561