J. Eur. Opt. Society-Rapid Publ. 22, 34( 2026) 345
( a)( b)
Fig. 1.( a) Optical scheme of the spectral-phase SPR 3D imaging biosensor.( b) Diagram of flow-cell.
Fig. 2. Spectral-phase SPR images:( a) water,( b) 15 % NaCl solution.( c) Reflection spectra for different concentrations of NaCl solutions ranged from 0 %( water) to 15 %.( d) Sensor response curve for different reflective index samples.
MPXV protein-neutralizing antibody interactions. Compared to the spectra-phase SPR imaging works we previously reported in [ 5, 6 ], this paper contributes to the first demonstration of MPXV neutralizing antibody detection using SPR imaging in the literature [ 7 ], while bovine serum albumin( BSA) and COVID-19 antibody detection were reported in [ 5, 6 ] respectively.
2 Material and methods
The experimental optical setup was constructed as described in Figure 1a. A fiber coupled halogen lamp was used as the broadband light source, which covers the spectral range of 350 – 1800 nm( Thorlab, model: OSL2). Subsequently, a telescope optical system consisting of a 10 objective lens( Olympus, model: 10 Olympus plan achromat objective) and a double convex achromatic lens( Edmund Optics, model: 50 mm dia. 75 mm) expanded the beam to approximately 30 mm in diameter. A 4 4 gold sensor array was sputtered onto an SF-18 equilateral glass prism for plasmonic biosensing. It is integrated with a polydimethylsiloxane( PDMS) based microfluidic flow cell for sample injection. The plasmonic sensing element was
placed between polarizer A and B with near perpendicular polarization angles to block light transmission. However, at plasmonic resonance, additional light phase difference was introduced between the p- and s-polarized light, that rotated the polarization ellipse and allowed light to pass through. As plasmonic excitation is a wavelength dependent process, a plasmonic spectral profile was encoded into the spectral-phase SPR image. Finally, a high-speed CMOS camera( Basler, model: acA1440-220uc) was used to capture sequence of plasmonic images up to 113 fps( corresponding to a temporal resolution of 0.0088 s), which were further analyzed using a custom-built MATLAB program. Spectral-phase SPR imaging enabled 2D detection. At video format, the sequence of SPR images can provide 3D multiplexed molecular bindings curves in the time domain. Figure 1b shows structure of the flow cell, where a flow chamber was patterned at the center of a PDMS layer. The size of the chamber was approximately 1.5 1.5 cm 2 and with the fluidic volume of 300 lL. During detection, a 5 mL syringe was connected to the flow cell through tubing for static sample injection.
MPXV L1R neutralizing antibodies( 40889-T62, 1 lg / lL), L1R protein( 40889-V07E, 0.25 lg / lL) and control BSA( 810651) protein samples were purchased from