Protein immobilization and detection on laser processed polystyrene surfaces

Abstract

The bovine serum albumin (BSA)-polystyrene (PS) interface layer is laser photo activated at 157 nm for site selective multiple target-protein immobilization. The 5-15 nm photon induced interface layer has different chemical, wetting, and stiffness properties than the PS photon processed surface. The irradiated areas exhibit target-protein binding, followed by localized probe-target protein detection. The photon induced chemical modification of the BSA-PS interface layer is identified by: (1) Morphological, imaging, and analysis of surface parameters with atomic force microscopy, (2) spectroscopic shift (4 cm−1), of the amide I group and formation of new C=N, NH2, C-O, C=O, and O-C=O groups following irradiation, identified with attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and (3) the different hydrophilic/hydrophobic and force-distance response of the bare PS and BSA-PS surfaces. Near field edge diffraction (Fresnel) fluorescence imaging specifies the threshold photon energy and the fluence required to optically detect the protein binding on the photon induced BSA-PS interface layer. By approximating the Fresnel integrals with analytical functions, the threshold photon energy and the fluence are expressed as the sum of zero, first, and second order harmonic terms of two characteristic diffracted modes and they are specified to be 8.73×10-9 Jand623 J m-2, respectively. Furthermore, a bioarray of three probe-target proteins is fabricated with 1.5 μm spatial resolution using a 157 nm laser microstepper. The methodology eliminates the use of intermediate polymer layers between the blocking BSA protein and the PS substrate in bioarray fabrication.

Photons Probe Entropic Potential Variation during Molecular Confinement in Nanocavities

“…The correlation between the surface parameter values and the levering porosity of the surface upon irradiation shows the formation of additional free space in the irradiated matrix. Indeed, because one photon at 157 nm dissociates one chemical bond [ 35 ], it is reasonable to accept excesive cavitation and a volume reduction of the matrix.…”

“…Also, VUV photon processed PHEMA matrixes attain higher contact angle values at different time intervals, compared with non-irradiated areas, exhibiting hydrophobic surfaces due to carbonization, Figure 9 b. The contact angle gradients clearly show the tendency of the PHEMA surfaces to enhance their hydrophobic response by lowering their surface energy [ 35 ]. Most important, the non-irradiated/irradiated matrixes show a similar time gradient of contact angles, suggesting similar values of diffusion constants for different porosities.…”

“…Indeed, photon-induced processing may alter the physical and chemical properties of organic surfaces and polymers. Particularly irradiation with Vacuum Ultraviolet light (VUV) in the spectral region between 110 to 180 nm implies an extensive modification of physical properties and functionalities of polymeric matrixes via breaking of chemical bonds and emerging of new ones [ 34 , 35 , 36 , 37 , 38 ]. Among others, photon processing of surfaces [ 39 , 40 ] is accompanied by a diversity of parameters, different porosities, sensing efficiencies, chemical stabilities, and excessive surface stressing.…”

Entropy and Random Walk Trails Water Confinement and Non-Thermal Equilibrium in Photon-Induced Nanocavities

“…Commonly, photon-processing of surfaces reconfigures their physicochemical properties, including thermodynamic potentials [ 37 , 38 , 39 , 40 ]. Irradiation of a polymeric matrix with vacuum ultraviolet (VUV) light in the spectral range from 110 to 180 nm entails an extensive modification of topological and thus of physical features, because of bond breaking and formation of new bonds.…”

“…However, no data exist for VUV processing of PAM surfaces, preventing thus precise tailoring of PAM’s physicochemical surface characteristics (surface roughness, structure size, elasticity, chemical composition, etc.) and the formation of controlled micro/nanopatterns and cavitations for different applications [ 37 , 42 , 43 , 63 , 64 ].…”