Spot morphology of non-contact printed protein molecules on non-porous substrates with a range of hydrophobicities

Abstract

Non-contact inkjet printing technology is one of the most promising tools for producing microarrays. The quality of the microarray depends on the type of the substrate used for printing biomolecules. Various porous and non-porous substrates have been used in the past, but due to low production cost and easy availability, non-porous substrates like glass and plastic are preferred over porous substrates. On these non-porous substrates, obtaining spot uniformity and a high signal to noise ratio is a big challenge. In our research work, we have modified pristine glass slides using various silanes to produce a range of hydrophobic glass substrates. The hydrophobicities of the slides expressed in the contact angle (θ) of a sessile drop of water were 49°, 61°, 75°, 88° and 103°. Using a non-contact inkjet printer, microarrays of biotinylated biomolecules (BSA and IgG) were produced on these modified glass substrates, pristine (untreated) glass and also on HTA polystyrene slides. The uniformity of the spots, reflecting the distribution of the biomolecules in the spots, was analyzed and compared using confocal laser scanning microscopy (CLSM). The quality of the spots was superior on the glass slide with a contact angle of ∼75°. We also investigated the influence of the hydrophobicity of the substrate on a two-step, real diagnostic antibody assay. This nucleic acid microarray immunoassay (NAMIA) for the detection of Staphylococcus aureus showed that on highly hydrophilic (θ < 10°) and hydrophobic substrates (θ > 100°) the assay signal was low, whereas an excellent signal was obtained on the substrates with intermediate contact angles, θ ∼ 61° and θ ∼ 75°, respectively.

Simultaneous Replication of Hydrophilic and Superhydrophobic Micropatterns through Area‐Selective Monomers Self‐Assembly

“…Through our results, surface energy mimicking demonstrates promising features for applications requiring patterned surface modifications, with or without micro/nanostructures. In microarray technology, for example, the results of Figure may be directly applicable to improve spot uniformity and read‐out sensitivity …”

Simulation and basic experiment of picoliter droplet micro-dispensing based on piezoelectric drive

“…Micro-dispensing technology has a great deal of applications in biology, microelectronic packaging, MEMS assembly and other related fields [1][2][3][4][5]. For example, it is usually necessary to connect different microparts with adhesive bonding to develop a complex and integrated microsystem, and microdroplets dispensing is one of the extremely important subtasks in the microsystem assembly and manufacturing.…”

Hexamethyldisilazane Modified Paper as an Ultra-sensitive Platform for Visual Detection of Hg2+, Co2+, Zn2+ and the Application to Semi-quantitative Determination of Hg2+ in Wastewater

“…The water contact angle (θ) on polystyrene modified paper was 110.9 ± 0.5 , which was higher than reported on a standard HTA polystyrene slide (θ ~92 ). 24,26 Even though Abe et al 25 already demonstrated the application of PS in producing barriers for hydrophilic channels, the consequence of PS modification on the cellulose surface was not reported. A significant difference in advancing and receding contact angle was observed on PS modified filter paper ( Table 1).…”

“…They observed higher signal density and improved signal-to-noise ratio on high hydrophobic glass slides (θ >90 ) as compared to pristine glass slides. 24 Recently, Feng et al 31 demonstrated that by supplying higher volumes of analyte solution, the sensitivity of the paper-based assay can be improved to μM range. On the other hand, Takahashi et al 32 also showed that by selective filtration-enrichment of Hg 2+ ions through dithizone nanofibercoated membrane, the limit of detection could be lowered to 10 ppb.…”

“…HMDS vapor adsorbs on the substrate surface as uniform layers, thus acts as a potential agent in improving the substrate's hydrophobicity. Earlier, Mujawar et al 24 successfully demonstrated the application of HMDS to produce hydrophobic glass slides, which were used as a platform for producing high quality microarrays. We observed low hysteresis on HMDS modified paper as compared to other surfaces (26.5 ± 3.6 ) ( Table 1).…”