414 JOURNAL OF COSMETIC SCIENCE NANOHYBRIDS FOR EX TRACTION/RELEASE OF DESIRABLE AT TRIBUTES AND FOR SCAVENGING OF ODORS AND TOXIC MATERIALS Ponisseril Somasundaran, Ph.D., S. Chakraborty, and S. Mehta Langmuir Center for Colloids and Interfaces Columbia University, New York, NY 10027 A major challenge in cosmetic industry is to incorporate water-incompatible perfume molecules into reliable carriers for release at desired rates and desired sites. Nanohybrid particles and polymers can be designed to encapsulate sensory attributes or scavenge odors from the surrounding environment and then to release them as required. In the present work, nanogel carrier particles and hybrid polymers were tested for their extraction and release capabilities. A series of functional nanogels, hydrophobic, ionic, dually modified with both hydrophobic and ionic groups and chiral types, were made by polymerization in nano­ emulsion of Span BO/Tween BO/hexane/water by gamma radiation. Dynamic light scattering and scanning electron micrograph revealed the size of the particles to range from 50-BOnm for dry particles to 150nm for wet. The size as well as sponginess could be altered by varying the crosslinking density. Encapsulation experiments were carried out with these nanogels to determine the effects of functionalization on extraction and release. As compared to the unmodified nanogels, the chemically modified for hydrophobicity and electrostatic charge showed considerably higher ability of extraction. The range and capacity of the nanogels could be controlled by determining the effects of these functional groups on their loading properties. Swelling was more apparent in alkaline medium than in acidic medium. The swelling behavior of the particles was determined by monitoring them using atomic force microscopy upon immersing them in water (figure 1 ). Although, in saline the efficiency of all types of nanogels was decreased, the hydrophobic nanogels showed much better performance than other types of nanogels. The release was observed to be pH dependent, change in pH thus offering a means of controlling the release of active substances. Linalyl acetate, a fragrance ingredient, was incorporated in the nanogels particles. It was observed that poly(acrylic acid) nanogels could extract 40% linalyl acetate(LA) from dispersion medium. The efficacy of extraction was enhanced by the introduction of hydrophobic moieties to the polymeric backbone. Figure 2 compares the extraction of linalyl acetate by unmodified and modified nanogels. Nanogels are also used in food industry for flavor encapsulation. The ability of starch starch nanoparticles to encapsulate vanillin, an ingredient that gives vanilla flavor, was evaluated and it was observed that succinic acid cross-linked starch nanoparticles extracted 25% vanillin in 6 hours. The kinetics of these nanoparticles for extraction of various active substances was investigated using surface plasmon resonance (SPR) technique. The evanescent behavior of the waves makes the SPR technique sensitive and surface specific to long and short changes in refractive index of the layer next to the substrate and hence to adsorption/desorption (extraction/release) of molecules in the surface layer. The release·

2006 ANNUAL SCIENTIFIC SEMINAR 415 rates of drug and fragrance were thus established based on changes in the refractive index of tightly bound layers of nanohybrids. It was observed that the release can be controlled by varying properties such as cross linking density, temperature sensitivity and swelling/ shrinking capacity. Along with fragrance, the potential of the nanogel particles to extract the overdosed drugs was studied. It was observed that poly(acrylic acid) nanoparticles could efficiently extract around 60% of bupivacaine and amitriptyline in IO minutes. The study also explored the synthesis and characterization of optically active chiral nanoparticles for extraction of attributes. Hydrophilically modified silicones (figure 3) or hydrophobically modified organic polymers (figure 4) have advantages of both polymers and surfactants. They have an ability to fold or unfold depending on their affinity with the surrounding medium, which can be effectively used to store and release attributes. Based on the above studies it is clear that nanogel particles and hybrid polymers that are appropriately modified for affinity to fragrance hold considerable potential for controlled release. Dry particle size., 40 nm Wet particle size= 140 nm Figme 1: Illustration of morphology of nanogels in dry and wet conditions using atomic force microscopy • 1tablc c:mulaion • Em.ulaion+ exc:cu waler • Em.ulaion+ cxceu oil 100 Silicone surfactant (1 % modified) II Propyl ..... modiW 1-,illlliMfflOlihl Ummilllll o---r---�--r----.---......---, 0 m Bl D Bl .D nme,milllll• Figure 2: Extraction of linalyl acetate(LA) by modified and lDIDlodified poly(acrylic acid) nanogels(PAANG). PAANG: 10mg in lOtnL of pH 7 buffer. LA: 0.010mg n■l\lral pH • pt-t-3.8 g't,7 Nae Figme 4: Extraction of organic actives by diluting the solution of hydrophobically modified polymers