In order to introduce alternative functions into mammalian cells and control them under ambient conditions, poly(N-isopropyl acrylamide) (PNIPAM) was immobilized on the cell surface. Cellular aggregation could be regulated by temperature change. In addition, separation of PNIPAM-conjugated glycoproteins was successfully performed.

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IFSCC Magazines, 12 (2009) (1) 3–7 It is generally well known that the surface of an inorganic UV‐protective powder used in a sunscreen formula is treated with a fatty acid or other hydrophobic chemicals to obtain a high water resistance. Due to the resulting strongly hydrophobic surface, the treatment has a clear drawback in that it allows the sunscreen to leave its base components on the skin after washing with regular soap. Therefore, in this study to develop an intelligent sunscreen formula that has a high water resistance and can be washed away easily with regular soap, we focused on a pH‐responsive polymer as the surface‐treatment agent for a UV‐protective powder. Numerous experiments led to the synthesis of the 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid/11‐methacrylamidoundecanoic acid (AMPS/MAU) copolymer, which is hydrophobic in acidic to neutral solution and hydrophilic in basic solution. Titanium dioxide subjected to surface treatment was treated with the AMPS/MAU copolymer showed a high pH‐responsiveness that was similar to that of the polymer. A W/O‐type sunscreen containing the pH‐responsive titanium dioxide showed a high water resistance as well as a high washability with regular soap. Keywords:  Detergent‐washable, pH‐responsive polymer, pH‐responsive powder, sun care product, water‐resistant

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