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

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%.

Automated summary

A biosensing system based on bioresponsive hydrogels for selective detection of C-Reactive protein (CRP) has been developed, utilizing Direct Laser Interference Patterning to create micro-gratings on the hydrogel substrates. The system achieved detection and quantification limits in human serum dilutions, showing potential for applications related to cardiovascular diseases and sepsis. Further amplification strategies improved sensitivity, widened the linear range, and enhanced limits of detection and quantification.