Reduced Blood Coagulation on Roll-to-Roll, Shrink-Induced Superhydrophobic Plastics

Abstract

The unique antiwetting properties of superhydrophobic (SH) surfaces prevent the adhesion of water and bodily fluids, including blood, urine, and saliva. While typical manufacturable approaches to create SH surfaces rely on chemical and structural modifications, such approaches are expensive, require postprocessing, and are often not biocompatible. By contrast, it is demonstrated that purely structural SH features are easily formed using high throughput roll-to-roll (R2R) manufacturing by shrinking a prestressed thermoplastic with a thin, stiff layer of silver and calcium. These features are subsequently embossed into any commercially available and Food and Drug Administration (FDA)-approved plastic. The R2R SH surfaces have contact angles >150° and contact angle hysteresis <10°. Importantly, the surfaces minimize blood adhesion, leading to reduced blood coagulation without the need for anticoagulants. SH surfaces have >4200× reduction of blood residue area compared to the nonstructured controls of the same material. In addition, blood clotting is reduced >5× using whole blood directly from the patient. Furthermore, these surfaces can be easily configured into 3D shapes, as demonstrated with SH tubes. With the simple scale-up production and the eliminated need for anticoagulants to prevent clotting, the proposed conformable SH surfaces can be impactful for a wide range of medical tools, including catheters and microfluidic channels.

Keywords: anticoagulation; biomaterial; blood clotting; roll-to-roll manufacturing; superhydrophobic.

Figure 1:

Sheet evaporation on PS was characterized with 20nm Ag + 5nm Ca, 20nm Ag + 10nm Ca, 25nm Ag + 5nm Ca, 25nm Ag + 10nm Ca, 30nm Ag + 5nm Ca, and 30nm Ag + 10nm Ca. A) i) Silver is first deposited, ii) then calcium is deposited in sheet evaporation. iii) The SH features are formed while shrinking the metalized film, and the SH features are iv) molded into an intermediary silicone and v) embossed into plastic to achieve the final product. B) SEM images of the hierarchical features in plastic show hierarchical winkles. Scale bars are 1μm for all images. C) CA of water and bodily fluids on all conditions are SH. D) CAH of water and bodily fluids on all conditions are SH.

Figure 2:

SH surfaces are fabricated in a R2R platform. A) i) 20nm Ag, then 5nm Ca are deposited on the pre-stressed PS film in a R2R deposition chamber, ii) the metalized PS shrink film is shrunk to achieve SH features, and iii) the SH features are imprinted into hard plastics. B) Materials are deposited on the shrink film in the VTT EVA R2R Evaporator Line. C) (i) A roll of metalized shrink film is 30cm × 300m. (ii) The metal film is shrunk), and (iii) large SH hard plastics are created. D) SEM images of the front, middle, and rear of the metalized PS roll were tested to show the consistency of deposition throughout the roll. Scale bars are 1μm for all SEM images. E) CA of water, urine, saliva, and blood on all conditions are SH. F) CAH of all fluids are SH on all conditions.

Figure 3:

Still images of blood sliding on flat and SH PP are taken with a high speed camera. A) Multiple drops of blood are required for blood to slide off the flat surface. Blood smears and partially slides off the flat surface within 15 seconds. B) One droplet of blood completely slides off the SH surface within 0.25 seconds and leaves no visual residue. Scale bar is 10mm for flat and SH. C) Blood residue area is reduced >4200x on the SH surface compared to flat. D) Significantly less blood volume adheres to the SH surface compared to flat (>28x).

Figure 4:

Blood coagulation is reduced on SH surfaces compared to flat. A) Fluorescently-labeled fibrinogen indicates blood coagulation on flat (top) and SH (bottom) surfaces. Scale bar is 200μm. B) SH surfaces have significantly less blood coagulation compared to flat (>5x reduction at 50min).

Figure 5:

SEM images of blood coagulation on flat and SH PP for 0–50min time points. A) Flat surfaces show platelet maturation and fibrin formation within the first 20min of incubation. B) SH surfaces have less mature platelets up to 40min and fibrin formation is less prominent at the lower time points. Scale bars are 1μm for all images.

Figure 6:

Metalized PS sheets are shrunk as rolled tubes with varying diameters. A) SH features are formed on the outside of the rolled PS, and when PDMS molds the features, SH PDMS tubes with features on the inside are created. Droplets of yellow food dye inside the tube have SH CA values. B) SH features are formed on the inside of the rolled PS, and when PDMS molds the features, SH cylinders with SH features on the outside are created.