Detection of leukemia markers using long-range surface plasmon waveguides functionalized with Protein G

Abstract

A novel optical biosensor based on long-range surface plasmon-polariton (LRSPP) waveguides is demonstrated for the detection of leukemia markers in patient serum using a functionalization strategy based on Protein G. The sensor consists of thin straight Au waveguides (5 μm × 35 nm × 3.2 mm) embedded in fluoropolymer CYTOP™ with a fluidic channel etched into the top cladding. B-cell leukemia is characterized by a high B-cell count and abnormal distribution of immunoglobulin G kappa (IgGκ) and lambda (IgGλ) light chains in serum. The detection of leukemic abnormalities in serum was performed based on determining IgGκ-to-IgGλ ratios (κ : λ). Three patient sera were tested: high kappa (HKS, κ : λ ~12.7 : 1), high lambda (HLS, λ : κ ~6.9 : 1) and normal (control) sera (NS, κ : λ ~1.7 : 1). Au waveguides were functionalized with Protein G and two complementary immobilization approaches were investigated: a) the reverse approach, where the Protein G surface is functionalized with patient serum and then tested against goat anti-human IgG light chains in buffer, and b) the direct approach, where the Protein G surface is functionalized with goat anti-human IgGs first and then tested against patient serum. The reverse approach was found to be more effective and robust because Protein G-functionalized surface performs as an "immunological filter" by capturing primarily IgGs out of the pool of serum proteins. For the reverse approach, the ratios measured were 3.7 : 1(κ : λ), 9.7 : 1(λ : κ) and 1.9 : 1(κ : λ) for HKS, HLS and NS, respectively, which compare favorably with corresponding protein densitometry measurements. The respective ratios for the direct approach were 2.6 : 1(κ : λ), 2.6 : 1(λ : κ) and 1.7 : 1(κ : λ). The binding strength and cross-reactivity of goat anti-human IgGs light chains were also determined using pure solutions. The LRSPP biosensor along with the innovative "reverse approach" can provide a low-cost and compact solution to B-cell leukemia screening.

Hybrid PDMS/glass microfluidics for high resolution imaging and application to sub-wavelength particle trapping

“…[2][3][4][5] It is common to use PDMS to fabricate channels for the immersion of nanostructure for sensing applications, such as ring resonators and photonic crystals. [6][7][8][9] Unfortunately, PDMS also has some limitations, 10 in particular when considering high-resolution imaging.In most silicon-based structures, the sample is opaque to visible light. Thus, the imaging has to be done through the microfluidic layer.…”

Current technological trends in biosensors, nanoparticle devices and biolabels: Hi‐tech network sensing applications

“…Optics-based biosensors provide an excellent visual detection method involving immobilization of detectors in a suitable source and use of varied operating mechanisms such as chips involving SPR variations, scattering and interferometry for diverse applications including biomedicine and diagnosis (Backmachuk et al, 2017;Krupin, Wang, & Berini, 2015;Torun et al, 2012;Wong, Sekaran, Adikan, & Berini, 2016;Zeng, Baillargeat, Ho, & Yong, 2014). Recently, simplified coupling of SPR with mass spectrometry resulted in the development of biosensors for rapid identification of cross-reacting molecules for industrial applications (Joshi, Zuilhof, van Beek, & Nielen, 2017).…”

Characterization of long-range plasmonic waveguides at visible to near-infrared regime

“…Integrated photonic devices based on LRSPP waveguides have been fabricated for passive light transmission, 6,7 signal modulation, 8,9 and biomolecular sensing. 10,11 Most of the LRSPP waveguides used polymer as the dielectric cladding layer due to the ease of fabrication and optical transparent properties, such as BCB, 6,8,[12][13][14] Cytop, [9][10][11] ZPU, 15,16 and Ormoclear. 13 By utilizing the thermo-optic effect of the polymer, 8,9 signal modulation can be further achieved.…”

“…Other works used inorganic materials such as SiO 2 and LiNbO 3 , [17][18][19] 7,20,21 but the fabrication process is relatively complicated compared with polymer claddings. Up to now, most of the work has been focused on the passive light transmission devices at the telecommunication wavelengths, [6][7][8][9][10][11][12] where the propagation losses are lower compared with shorter wavelengths. However, plasmonic waveguides operating at wavelengths shorter than the telecommunication wavelength are gaining attentions in recent years.…”