Optical detection of Human Hemoglobin by a Molecularly Imprinted Polymer prepared by a novel vapor-phase synthesis

Di.S.Te.B.A. (DIPARTIMENTO di SCIENZE e TECNOLOGIE BIOLOGICHE e AMBIENTALI) Tiziano Di Giulio, Martina Corsi, Stefano Mariani, Cosimino Malitesta, Giuseppe Barillaro, Elisabetta Mazzotta OPTICAL DETECTION OF HUMAN HEMOGLOBIN BY A MOLECULARLY IMPRINTED POLYMER PREPARED BY A NOVEL VAPOR-PHASE SYNTHESIS columnar pores with size 50 nm (diameter) and aspect ratio of 150 ✓Increasingly exploited in optical (bio)sensing applications ✓Effective tuning of the refractive index with facile preparation of different optical structures (i.e., interferometers, resonant cavities, waveguides) ✓High effective surface for the accommodation of receptors and target molecules Top-view SEM image of PSi scaffold. Scale bar: 100 nm. Porous silicon (PSi) photonic crystals as interferometers Tiziano Di Giulio OPTICAL DETECTION OF HUMAN HEMOGLOBIN BY A MOLECULARLY IMPRINTED POLYMER PREPARED BY A NOVEL VAPOR-PHASE SYNTHESIS Thickness: 4m Porous diameter: 50 nm Porosity: 75% Optical sensing based on porous silicon (PSiO2), as interferometer light reflecte d light Signal modification is produced by: A) insertion/grafting; B) removal or C) adsorption of compounds on porous silicon layer A B C A B C m=2nd/λm EOT (effective optical thickness): 2nL Wavelength (nm) Rel. intensity Frequency (nm-1) Rel. intensity FFT Tiziano Di Giulio OPTICAL DETECTION OF HUMAN HEMOGLOBIN BY A MOLECULARLY IMPRINTED POLYMER PREPARED BY A NOVEL VAPOR-PHASE SYNTHESIS n: refractive index; L: thickness of porous layer. Target (=template) removal imprinted cavities with “molecular memory” Target selective rebinding MIPs as artificial receptors Tiziano Di Giulio OPTICAL DETECTION OF HUMAN HEMOGLOBIN BY A MOLECULARLY IMPRINTED POLYMER PREPARED BY A NOVEL VAPOR-PHASE SYNTHESIS MIPs must provide: •Stable polymeric material •Recognition abilities comparable to those of natural biological systems •High selectivity ‘‘Plastic antibodies’’ Clinical relevance of human haemoglobin (HHb) detection for several diseases, including anemia, cardiovascular risk, and coronary artery disease Human hemoglobin (HHb) chosen as target molecule HHb (yellow crosses) adsorbed on nanostructured porous silicon/oxidazing agent (orange dots) (FeCl3) Target rebinding/recognition 25 °C ambient pressure Target removal Py vapours liquid Py Chamber satured with Py vapours PPy synthesis Synthesis of PPy-based MIP on PSiO2 interferometer by vapor-phase synthesis Polymerization (monomer) (polymer backbone) 2. APTES linking 1. PSiO2scaffold 5. PPy vapor deposition 3. Glutaraldehyde binding 6. HHb removal 4. HHb binding 500 600 700 800 900 0 5 10 15 20 25 30 35 APTES HHb Protein washing Reflectance (%) Wavelength (nm) PSiO2 Glutaraldehyde PPy deposition PPy-based MIP vapor-phase synthesis HHb rebinding Two linear regions: 0.1-1 mg mL-1 and 1-8 mg mL-1. LOD: 0.024 mg mL-1 Reproducibility: 1.4% (in the low concentration range), 16.5% (considering the entire concentration range) (RSD%, n=3) Imprinting Factor (I.F.): 13.1 Optical sensing of Human hemoglobin (HHb) MIP-based sensor 50 l of sample Optical sensing of Human hemoglobin (HHb) 0 1 10 20 30 0 20 40 60 80 100 120 140 EOT - EOT0 (nm) Time (days) HHb rebinding MIP-based sensor