Contamination and carryover free handling of complex fluids using lubricant-infused pipette tips

Abstract

Cross-contamination of biological samples during handling and preparation, is a major issue in laboratory setups, leading to false-positives or false-negatives. Sample carryover residue in pipette tips contributes greatly to this issue. Most pipette tips on the market are manufactured with hydrophobic polymers that are able to repel high surface tension liquids, yet they lack in performance when low surface tension liquids and viscous fluids are involved. Moreover, hydrophobicity of pipette tips can result in hydrophobic adsorption of biomolecules, causing inaccuracies and loss in precision during pipetting. Here we propose the use of lubricant-infused surface (LIS) technology to achieve omniphobic properties in pipette tips. Using a versatile and simple design, the inner lumen of commercially available pipette tips was coated with a fluorosilane (FS) layer using chemical vapor deposition (CVD). The presence of FS groups on the tips is confirmed by x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) tests. After lubrication of the tips through a fluorinated lubricant, the omniphobicity and repellent behaviour of the tips drastically enhanced which are revealed via static and hysteresis contact angle measurements. The repellency of the lubricant-infused pipette tips against physical adsorption is investigated through pipetting a food coloring dye as well as human blood samples and are compared to the untreated tips. The results show significantly less amount carryover residue when the lubricant-infused tips are utilized compared to commercially available ones. We also demonstrate the lubricant-infused tips reduce bacteria contamination of the inner lumen by 3 to 6-log (over 99%, depending on the tip size) after pipetting up and down the bacteria solution.

Strategies to Prevent Bacterial Infections on Titanium-Based Orthopedic and Dental Implants

“…Inspired by the Nepenthes pitcher plant, liquid-infused surfaces (LISs) are a class of functional materials with a tethered layer of liquid, creating a smooth interface. [74][75][76][77][78][79][80][81][82] LISs are recognized for their stable liquid-repelling behavior under low sliding angles. 83 For the LIS to be stable and repellant, the substrate must have a high affinity to the lubricant, and the lubricant must be immiscible with the liquid that needs repelling.…”

Wetting ridges on slippery liquid-infused porous surfaces

“…For instance, silicone oil-infused porous polydimethylsiloxane substrates with a lubricant thickness of ∼26 µm have been shown to experience complete lubricant loss under flow with a shear stress of 7 mPa in 7 days, increasing the contact angle hysteresis substantially and degrading the repellency of these SLIPS [41]. Furthermore, lubricant depleted from SLIPS has been shown to contaminate the contacting liquids [42][43][44][45], such as water collected from fog and biofluids (blood, urine, saliva) used in bioanalysis applications [46]. Because of its biocompatibility, silicone oil is one of the most common lubricants used to make SLIPS.…”

Superomniphobic and Photoactive Surface Presents Antimicrobial Properties by Repelling and Killing Pathogens

“…Pathogen-repellant surface technologies can be separated into two distinct categories: liquid-infused coatings and air-infused coatings . Liquid-infused coatings are created by the infusion of a lubricating liquid into the surface structure or chemical coating. − This lubricating liquid layer is typically selected to be immiscible with the contaminating media (oil lubricant for water repulsion), which reduces the adhesion of the contaminate to the surface. ,, Air-infused coatings function by trapping air pockets within their surface structure, inhibiting the homogeneous wetting of the solid surface . The resulting unique wetting state of air-infused coatings, also known as Cassie–Baxter states, is responsible for the observed superhydrophobic and oleophobic properties of these materials. , Generally, both classes of surfaces are manufactured to have rough surfaces with high surface areas and are typically either porous, microstructured, nanostructured, or hierarchically structured. ,, For both liquid- and air-infused surfaces, structural hierarchy has resulted in a significant increase in liquid repellency and robustness of surface properties. , The hierarchical structure used for liquid-infused surfaces helps retain larger amounts of the lubricating liquid within the structure, while for air-infused surfaces, the hierarchical structure helps to increase the stability of the air pockets within the surface .…”