**4. Conclusions**

transparency. However, such nanosheets possess centimeter size and are only suitable for adhesion to relatively broad surfaces. They are often difficult to adhere to irregular and uneven surfaces because of centimeter size. In our recent study, we have discovered that the frag‐ mented submillimeter-sized nanosheets composed of poly(lactic acid) were adhered to the various surfaces in a spread out configuration that looks like "patchwork" [25, 26]. Once the nanosheets dried on the surface, they were difficult to detach from the surface by even washing with water. Moreover, we have demonstrated that the irregular and uneven surfaces such as a needles and rubbers etc. are effectively coated with the patchwork-like coating of the fragmented nanosheets by just casting or dipping [25, 26]. In this section, we introduce the fragmented nanosheets composed of PIPC and SPUPC series to coat irregular and uneven

Homogenized

water

10 mm

, esti‐

(30,000 rpm)

**Fragmented PC- polymer nanosheets** PC-polymer nanosheets

SiO2

*PET plate Fragmented PIPC-1 Fragmented SPUPC-2*

water Suspended

in water

Fig. 5 (a) Fabrication of fragmented nanosheets composed of PIPC-1 and SPUPC-2. (b) Macroscopic image of fragmented PIPC-1 nanosheets (left tube) suspended in distilled water. Right tube shows only distilled water. (c) SEM images of fragmented nanosheet surfaces after

**Figure 5.** (a) Fabrication of fragmented nanosheets composed od PIPC-1 and SPUPC-2. (b) Macroscopic image of frag‐ mented PIPC-1 nanosheets (left tube)suspended in distilled water. Right tube shows only distilled water. (c) SEM im‐

We herein focus on the fragmented PIPC-1 nanosheets as follows. First, we fabricated abundant self-standing nanosheets with centimeter size by a simple multi-layering process of watersoluble PVA and PIPC nanosheets combined with a peeling technique, according to our reports [25, 26]. Concretely, a 100 mg/mL solution of PVA as a water-soluble sacrificial layer was first spin-coated on a SiO2 substrate at 4000 rpm for 20 s, followed by a drying process as depicted in Fig. 5a. Next, a chloroform solution of 10 mg/mL PIPC-1 was spin-coated on the PVA-coated substrate under the same conditions. Moreover, the multi-layering of PVA and PIPC-1 was repeated twenty times on the substrate. By dissolution of PVA layers in water, tewenty sheets of PIPC-1 nanosheets were obtained. Next, the obtained PIPC-1 nanosheets were fragmented with a homogenzer. When the PIPC-1 nanosheets (size: 40 × 40 mm, thickness: 42 nm) in distilled water were homogenized at 30,000 rpm for 10 min, they were instantly fragmented. The obtained nanosheets were homogeneously suspended in water and the turbidity of the suspension was quite increased as shown in Fig. 5b. In fact, the surface area of one fragmented nanosheet 10 min after homogenizaion was significantly decreased to 6800 ± 208 μm2

mating that the average size of the nanosheet was approximately 80 μm. Using the same

surfaces and the evaluation of blood compatibility.

Multi-layering

(4,000 rpm, 20 s)

contact with platelet-rich plasma for 2h at 37oC.

ages of fragmented nanosheet surfaces after contact with platelet-rich plasma for 2h at 37°C.

(70oC, 90 s)

and drying PVA PC-polymer

**(b) (c)**

SiO2 (40 x 40 mm)

14 Advances in Bioengineering

**(a)**

We have synthesized novel aromatic diamine and diol monomers containing PC group to develop the new biocompatible polycondensation-or polyaddition-type polymers. The obtained polymers exhibited good solubility with aprotic polar solvents and thermostability unlike MPC polymers. Using these polymers, we have succeeded in the fabrication of selfstanding nanosheets with a thickness less than 100 nm. The PC-polymer nanosheets exhibited high adhesiveness to the various surfaces, and the surface of adhered nanosheets represented the good blood compatibility based on the platelet adhesion test. Furthermore, we have developed the fragmented nanosheets with submillimeter-size to coat irregular and uneven surfaces by controlling the size of the nanosheets. In fact, fragmented nanosheets were effectively coated with the patchwork-like adhesion behavior by just casting or dipping and provided blood compatibility to the various surfaces. Hence, these nanosheets composed of PC-containing polymers may be great promise as novel coating materials and surface modi‐ fiers to provide the biocompatibility to the surface of various medical devices such as catheters, artificial organs, microfluidic devices, etc.
