NEW YORK--More than 1,000 attendees from around the world gathered in an unseasonably warm New York City on Dec. 11–12, 2008, for the annual SCC Scientific Meeting and Technology Showcase. The program offered a variety of subjects in personal care; from multicultural formulating and sustainability, to tissue engineering and a special polymer/surfactant interaction tribute session in memory of Des Goddard.
Multicultural Skin Care/Technology
The event opened with a scientific session focused on multicultural skin care technology, moderated by Zoe Diana Draelos, MD, a dermatologist in private practice and a primary investigator for Dermatology Consulting Services. The final talk of the opening session featured the Frontiers of Science Award Lecture, sponsored by Cosmetics & Toiletries magazine.
Pyridoxine: The first speaker, Hitoshi Masaki, PhD, president of Nikkol Chemicals Group, Cosmos Technical Center Co., presented on pyridoxine’s ability to induce filaggrin in human keratinocytes. According to Masaki, pyridoxine, also known as vitamin B6, supports protein synthesis and amino acid and lipid metabolism. Masaki’s team investigated the physiological effects of vitamin B6 to find a derivative that can be used to treat dermatitis. They found that synthesized vitamin B6 tri-isopalmitate (VB6-IP) maintained stability in formulations, in addition to performing in a similar fashion to vitamin B6. The group noted that VB6-UO accelerates filaggrin production similarly to vitamin B6 and improves the water contact of the skin surface.
Confocal Raman Spectroscopy: David J. Moore, PhD, senior director of materials science at ISP’s corporate research center, followed Masaki’s presentation with his findings on confocal Raman spectroscopy. Moore explained that a resolution of 1 micron can be achieved with Raman, and 2–3 microns can further be obtained with confocal, enabling a closer look at biological tissue samples. According to Moore, confocal Raman allows researchers to take an intact tissue sample and observe the molecular organization of the tissue for information on the fluidity of the lipids in the sample. This reportedly is useful in examining mechanisms of penetration. The molecular structure can be used to view the pro-drug to drug conversion within skin, and the ability to monitor changes in chemistry is direct and non-destructive.
“If the drug crystallizes out, you can see that in the confocal spectroscopy,” commented Moore, whose initial studies were more relevant to pharmaceutical applications but whose current work focused on cosmetic applications. “We have a lot of interest in lamellar lipid gel technologies to mimic the physical organization of intercellular skin lipid lamellar phases,” added Moore. His team took tape-stripping data to determine stratum corneum delivery. Salicylic acid penetration into the stratum corneum was measured up to 30 mum. Also, a tocopheryl phosphate lipophilic complex was tested for its confocal depth and found mostly in the stratum corneum. Moore’s team concluded that confocal Raman spectroscopy is a powerful technique for ex vivo skin delivery experiments and has become much more widely used in cosmetics.
Skin color variations: Draelos, the session’s moderator, then defined the variables found in different skin tones and discussed technologies to address them. “If you head under the dermis, it looks and feels the same," said Draelos, who explained that melanin production is the primary differentiating factor in multicultural skin. She noted there is only a 30 melanin unit difference between European and African skin. The melanocortin-1 receptor has 954 nucleotides and controls melanin production, according to Draelos.
Relating to the differing mechanisms in skin, Draelos discussed sunlight and skin's reaction to it. “Vitamin D is not a vitamin, it is a hormone,” she said, adding that decreased sunlight will lead to decreased vitamin D hormones and as a result, vitamin D deficiency occurs in 50% of fair-skinned persons over the age of 50. Draelos went on to define pheomelanin, a polymer of benzothiazine, which accounts for red skin tones. “It is genetically linked with immunologic deficiencies, high incidence of skin cancer and higher allergies, “ added Draelos, who found that pheomelanin is problematic and becomes a cancer-causing substance when exposed to UV radiation.
Draelos noted that small mutations and damages in the DNA lead to wrinkles and the inability of skin to reproduce collagen. These mutations result from melanin’s decreasing abilty to protect the nuclear DNA. Melanin production is also a response to injury. “Tanning is a result of injury, not a result of skin health. It is a result of skin protection, not a sign of beauty,” stated Draelos. Melanin production can occur without sun exposure through the melanocyte stimulating hormone (MSH). This hormone is released during pregnancy, darkening the face, areola and central abdomen. Skin lightening products do not work on this type of pigmentation, Draelos explained, noting that only the alteration of estrogen production will accomplish this.
Finally, in considering the variants between different skin ethnicities, Draelos noted there are definite sunscreen opportunities on the market. Since black skin becomes hotter with UV exposure than white skin, Draelos suggests that sun protection products for darker skin focus on heat dissipation. Black skin also dissipates sweat better than white skin, and dark skin color confers better thermoregulation. Besides sunscreens, Draelos also finds there is a need for more effective pigment lightening preparations for dark skin. “It is easier to stimulate melanin production than to discontinue it,” said Draelos. She explained that hydroquinone is cytotoxic to melanocytes, adding that “black skin gets paradoxically darker when hydroquinone is applied.” And to address the aforementioned vitamin D deficiency, Draelos recommends that the daily allowance be revised—from 400 mL to 1000 mL per day.
C&T magazine Frontiers of Science Award Lecture—Tissue engineering: Buddy Ratner, PhD, director of the University of Washington Engineered Biomaterials Engineering Research Center, and professor of bioengineering and chemical engineering at the University of Washington, spoke to attendees about the new era of tissue engineering. “I believe that tissue engineering will revolutionize cosmetic strategies and medicine in the next 10 years, which is a [relatively] short period of time,” began Ratner. He explained how tissue engineering uses ideas from biology, medicine and engineering to grow living tissues and gave examples of tissue engineering that is already taking place; for instance, a bladder, a trachea, a human fibroblast-derived dermal substitute, and teeth have already been engineered and implanted into living organisms.
Tissue engineering has saved lives; however Ratner pointed out that alternate solutions such as using pigs organs for transplant simply do not work as well. Ratner suggested that tissue engineering cannot only be used for tissue and organ repair, but can also be used for cosmetic enhancement, devices to treat diseases, food production, implantable drug delivery devices, cosmetic toxicology testing and basic studies on tissue formation. In addition, engineered tissues also could be used in wrinkle fillers and stem cell creams. For Ratner, tissue engineering ultimately will reduce deaths by replacing heart muscles or potentially, the entire heart. The possibilities are endless.
After the morning session, attendees gathered at the awards luncheon. The prestigious Maison G. deNavarre Medal Award was presented to Kevin D. Cooper, MD, a professor and chairman of the department of dermatology, and professor of oncology and pathology, at the Case School of Medicine at Case Western Reserve University and University Hospitals Case Medical Center. Cooper was recognized for his work in the biology of UV-induced immune suppression, which has been critical in the design of sunscreens with photoprotection beyond sunburn protection. He was also recognized for his research on UV radiation, including studies on antigen-presenting cells and psoriatic skin.
Additional awards were presented during the luncheon for outstanding work in the industry. These included the Shaw Mudge Award, sponsored by Ciba Corp., which was presented to Shaow B. Lin, PhD, Stephanie Postiaux and Joanna Newton, PhD, for their paper titled, Vesicular Delivery Systems: From Phospholipids to Silicones for Targeted Skin Sites. This paper was named Best Paper at the 2008 Annual Scientific Seminar.
The Allan B. Black Award, sponsored by Presperse LLC, was given to Leila S. Song, PhD, Gabriel E. Uzunian, Betty F. Aucar and James B. Carrol, Jr., PhD, for their paper titled, Complex Effect Pigments: Innovative Solutions for Ethnic Color Cosmetics. The award recognizes the best paper on makeup technology.
Arch Personal Care Products also presented the Hans A. Schaeffer Award to Michel Daley, PhD, and David W. Koenig, PhD, for their paper titled, Removal of Microbial Pathogens from Skin Using Magnet. This award recognizes the most innovative paper. Finally, the last award at the luncheon was the Joseph P. Ciaudelli Award, sponsored by Croda Inc., which was given to Karin Keis, PhD, Craig L. Huemmer and Yash K. Kamath, PhD, for their paper titled, Effect of Oil Films on Moisture Vapor Absorption on Human Hair. This award recognizes the best article submitted to the Journal of Cosmetic Science on hair care.
In addition, Cosmetics & Toiletries magazine group publisher Dave Brambert presented Buddy Ratner, PhD, with the Frontiers of Science Award Lecture. Attendees adjourned into the concurrent afternoon sessions, featuring both in vitro alternatives and multicultural hair care technology.
In Vitro Alternatives
During the afternoon session on in vitro alternatives, moderator Mindy S. Goldstein, PhD, of Esteé Lauder, introduced talks ranging from the activity of glycokines, as measured by a noninvasive, non-touch "elasticity" technology, anin vitro stressor model to measure cellular senesce and a new study focused on the papillary dermis to target aging; to in vitro evaluations to evaluate UVA protection, based on FDA guidelines and a novel ex vivo pig skin organ culture model to test cosmetic materials for safety and efficacy.
Cell elasticity and cohesion: Denise Gabriele, vice president of sales and marketing for Sederma Inc., introduced studies on glycokines—sugar molecules that have been shown to exhibit specific messenger activity and improve tissue cohesion. Fitting with the session's theme, the material's efficacy was measured via the company's patented Aeroflexmeter, a device mounted and positioned to send compressed air to the skin. When the air blows against the skin, the skin flexes and when the air stops, the skin returns to its initial state. The device uses a laser to measure the skin's elasticity before, during and after being exposed to the compressed air. This model, according to Gabriele, can be used to test materials targeted to increase skin's elasticity and described the device as measuring "resistance to deformation." "Older skin was found to have no resistance [to the air], whereas younger skin is more taught," said Gabriele. She added that the device also can look at the displacement of water in skin. In the test setup, glycokines were tested and found to repair damaged skin tissue by increasing skin elasticity; corneometer and moisture meter measurements also were taken. Attendees were interested in this model of testing product efficacy. Gabriele conceded that the opportunites for its use were only just begnning to be realized.
Stress-induced senescence: Following Gabriele, Karl Lintner, PhD, technical advisor to Croda/Sederma, described methods to study cellular senescence in vitro. To set the stage, Lintner introduced the two primary approaches to aging. "You can reduce aging by preventing stressors, or you can reverse/slow the signs of aging," said Lintner, who chose stress as the focus of his in vitro work. According to Lintner, to study the mechanisms of aging, several stress-induced premature senescence (SIPS) methods are used. These range from monolayer cell culture studies, fibroblast lifespan and DNA arrays to measure gene activity, to ex vivo studies on human skin explants. Specifically, genes can artificially be aged by hydrogen peroxide treatments, UV irradiation and glucocorticoid treatment.
Lintner concluded, after reviewing the pros and cons of each of the treatment types, that although SIPS can be useful to screen for antiaging activity based on antioxidant or enzyme inhibitory activity, that it is difficult to know whether treatment materials are targeting the aging mechanism or the effects of the SIPS themselves. A more realistic approach to senescence studies, according to Lintner, is obtained with longer-term cell culture studies involving proliferation rates, marker proteins and telomere analysis. This topic of telomeres also was a topic of discussion during the IFSCC Congress held in Barcelona. Lintner shared an interesting fact, which may already be known to some: telomeres are longer in lobsters and these sea creatures are noted for their long lifespan. "Lobsters have been called immortal," said Lintner, who noted myths about their everlasting lives.
During his closing, Lintner referenced many recent studies that have surfaced involving resveratrol and its potential to lengthen lifespan. "It's the youth molecule," said Lintner. He concluded that more clinical studies are needed, and that perhaps the answer does not lie in studies in vivo, or in vitro, but perhaps "in vino," much to attendees' satisfaction.
Matrix proteins and expression profiles: David Boudier, scientific communications manager for Silab, next presented research focused on the superior dermis in close contact with the Dermal Epidermal Junction (DEJ); the papillary dermis. In his presentation, Boudier described an in vitro model of intrinsic aging focused on the papillary dermis to study the profiles of different matrix proteins. Specifically, the in vitro model of senescent papillary fibroblasts by replication was validated by visualization of the marker of senescence, beta-galactosidase. The described model showed how early deterioration of the oxytalan fibers begins at 30–40 years of age, and that they gradually disappear; the expression of collagens by the papillary fibroblasts also is impaired. As a consequence, the number and size of the dermal papillae are reduced and expressed in the form of DEJ flattening. Thus, a treatment based on tiger nut tubers (Cyperus esculentis) was designed to restore the normal expression of these dermal markers.
In vitro UVA evaluation: Olga Dueva-Koganov, personal scientist in the home and personal care division at Ciba, next presented how to meet the US FDA's highest standard of UVA rating by optimizing sunscreen compositions and by assuring their photostability. This very complex method included, in brief: a discussion of pre-irradiation, spectral power distribution normalization, test mediums--including a replica skin substrate and quartz plates, application time, transmittance calculations, test articles and more. During the Q&A session, attendees commended the "enormous" amount of work put into this study. In the end, Dueva-Koganov concluded that her research established test conditions to closely and successfully measure what the FDA requires of sunsreens.
Pig skin organ culture model: Ending the day's session on in vitro testing, Gabriele Vielhaber, PhD, vice president of innovation/R&D life essentials at Symrise, presented "A Novel Ex vivo Pig Skin Organ Culture Model for Use in Efficacy and Safety Testing." This approach to testing meets two needs, according to Vielhaber, namely consumer demand for ethics and the Cosmetics Directive in Europe, banning the use of animals. This technology won Cosmetics & Toiletries magazine's International Technology Award at HBA in September. In essence, the pig skin organ culture model (PSOCM) utilizes skin taken from animals dedicated to food production, maintains its viability, and employs it to test for safety and efficacy of cosmetic products and materials. In the end, Vielhaber concluded the technology to be an "ethical, versatile and economical alternative" to animal testing.
Multicultural Hair Care Technology
The session on multicultural hair care technology was moderated by Colleen M. Rocafort, global business head of polymer systems for the Home and Personal Care Business Line at Ciba Corp. Rocafort welcomed the first speaker, Andrea Keenan, technical service/sales service support of the personal care polymers at Rohm and Haas.
Shine and hold for ethnic hair: Keenan and her team compared a number of polymers in Latin, African, Asian and Caucasian hair for percentage changes in luster and surface roughness. She compared a number of copolymers after finding that polymers are good film-formers and have the ability to spread on hair fibers during evaporation; they optimize viscosity and balance the coverage and thickness of films. In addition, their surface tension allows for increased wetting/spreading. Keenan’s team found that polymers deliver a discernible shine across a variety of ethnic hair types. They are multifunctional by providing superior hold and style. However, it was the acrylates/hydroxyesters acrylates copolymer that delivered not only shine but also strong hold and style control.
Water/sweat-resistant styling: Following Keenan was Duane G. Krzysik, senior research and development associate for hair care applications for Noveon Consumer Specialties of Lubrizol Advanced Materials Inc. Similar to Keenan, Krzysik spoke to attendees about a polymer comparison, namely water-resistant polymers associated with extreme styling. His team tested three polymers: polyacrylate-14, polyacrylate-2 crosspolymer and acrylate copolymer. He addressed the polymers separately and in combination for sweat resistance and style hold and found that polyacrylate-2 crosspolymer provided water/sweat-resistance alone or in combination with acrylate polymers. The researchers deduced that specialized, hydrophobically modified acrylate film-forming polymers improved the water/sweat resistance properties of styling formulations.
Hair moisture content: Michael Davis, lead scientist of the product claims support division of hair care for P&G Beauty, then presented on hair moisture measurement. According to Davis, hair increased in diameter 15% or more when wet. As water content becomes higher, so does the frictional force. “What really is moisturized hair? Why would people want all that moisture in it when it seems to have negative effects?” asked Davis during his his presentation. Davis’s team investigated hair at different levels of humidity. They also asked blindfolded panelists to assess whether they thought their hair felt moisturized.
Researchers determined that there was no correlation between the moisture content of the hair and the sensation of moisturization. Rather, there is a correlation of moisturization and smoothness or softness. The researchers also found that constant environmental fluctuation inhibited hair to reach the equilibrium state. “Everyone’s got their unique humidity pattern. Consumers can have up to 20 mL of water in their hair, and that’s a lot of water. There is no real steady state. How can we achieve moisturization when the consumer’s humidity [in the] environment is always changing?” said Davis, who believes that this work could lead to a middle ground on the true meaning of moisturized hair.
Water distribution in hair: Yash Kamath, PhD, founder of Kamath Consulting, rounded out the session’s presentations with a talk on small angle neutron scattering (SANS) studies of human hair. “We can get information about moisture distribution in human hair by replacing H2O with D2O and then carrying out SANS,” said Kamath. According to Kamath’s data, most of the water is present in the microporous regions (cuticle) and less in the nanoporous regions (cortex and CMC). He did not conduct a study of the CMC because it is too large. Kamath finds that this information could be useful in modifying the hair to control the amount of water present, and that the desired effect on the property of the hair can be achieved. Moisturization of the cortex, according to Kamath, can lead to improved bending properties. “There is a small amount of water in the cortex that can be manipulated easily to control the suppleness of the hair,” said Kamath.
The first day’s sessions were culminated with the Suppliers’ Cocktail Reception in the Grand Ballroom of the New York Hilton. Attendees mingled with one another while sampling the smorgasbord of sushi, pasta, shellfish and freshly carved meat and sipping on cocktails with lively background music. The night would not have been complete without dancing and a performance by the SCC band, the Chem-Tones.
Tribute to Des Goddard
Day Two of the SCC Annual Meeting and Technology showcase featured an all-day technical session dedicated to Des Goddard, focused on polymer and surfactant interactions.
Des Goddard, who passed away in December 2007, was a pioneer in the cosmetics and personal care industry. Born in South Africa in 1926, he attended Queen’s College as an undergraduate and began his research work at Rhodes University, leading to his masters of science degree on conductimetric chemistry, which he earned in 1948. From there, “Des,” as he became known, moved on to Downing College in Cambridge, working initially with A.E. Alexander in what was then the Department of Colloid Science.
Brian Pethica, PhD, senior scientist of the department of chemical engineering at Princeton, wrote in the 2008 SCC meeting proceedings book that Des “expanded out from that early effort in the broad field of polymer/surfactant interactions, particularly as they related to skin and hair properties. He became an acknowledged leader and contributor to the science of cosmetics and leading member of the society meeting here today.” Pethica added that Des built up a leading body of high quality papers on these leading systems relevant to the aspects of surface and colloid science in and beyond cosmetology.
From Cambridge, Des went to Unilever Research near Liverpool, where he met and married his wife, Norah. Together they moved to Canada, where Des first worked at the National Research Council in Ottawa, and then with Canadian Industries. Des then moved to New Jersey to renew his association with Unilever Research at the Edgewater facility, where he continued his scientific work, producing leading papers on surfaces, colloids and polymer solution chemistry. From Edgewater, Des moved to Tarrytown to begin work with the Union Carbide Research Laboratory, continuing to publish his work.
Pethica’s writing in the proceedings continued: “Many taking part in this conference could give better account of the contributions Des made to our knowledge of hair and skin,” which each speaker did throughout the day, recounting tales and experiences they had with Des personally, or in continuing his work. “His contribution and enthusiasm for science and technology did not end with his retirement in 1992,” Pethica continues. “Among other leading contributions, I note the widely read book co-authored by K.P. Ananth, PhD, of Unilever R&D, Interactions of Surfactants with Polymers and Proteins in 1993, and the volume he co-authored with James Gruber, PhD, director of R&D at Arch Personal Care, Principles of Polymer Science and Technology in Cosmetics and Personal Care in 1999.
Pethica ended, “In reflecting on these contributions to science, let us also celebrate the contribution to human health and well-being through the improvements to personal care brought to a countless multitude by the insights, scientific skills, teamwork and achievements of our late colleague, Desmond Goddard. For these, we thank him, and will recall him often in the years to come.”
Polymer/Surfactant Delivery Systems for Personal Care
Day two of the meetings kicked off with introductions by Wil Hemker, of the University of Akron Research Foundation, of speakers for the morning session tribute to Des Goddard. Topics in the first session ranged from advances in surfactant interactions with proteins and polymer-surfactant interactions, to the modeling of polycation surfactant complexes in shampoos with deposition properties and polymer-surfactant association for improved tissue compatibility.
Surfactant interactions with proteins and SC: K.P. Ananthapadmanabhan (Ananth), PhD, of Unilever in Trumbull, discussed the interaction of surfactants with proteins, which has been a topic of interest over the past several decades. According to Ananth, it is well-known that surfactants interact strongly with the stratum corneum (SC) proteins, leading to their swelling and denaturation, and that they have high potential to cause irritation, erythema and itch. This reaction occurs via a “series of events that lead to increasing pore size.” He noted that the tendency of surfactants to interact with proteins follows the order: anionic surfactants > amphoteric surfactants > nonionic surfactants.
His recent work shows that protein denaturation potential of surfactants scales with micelle charge density, and that this correlation has been found for a range of surfactants and surfactant mixtures. Thus, micellar charge density provides an “irritation ruler” and can allow for the prediction of skin irritation potential of surfactants.
Fine-tuning polymer/surfactant interactions: Following Ananth, Susan Jordan, PhD, of Dow Chemical, honored Des before beginning her discussion on polymer-surfactant interactions. “Over thirty years, Des Goddard introduced state-of-the-art methodologies to the personal care industry.” She referenced techniques he introduced, such as: streaming potential, atomic force microscopy (AFM), radio-labeled polymers and scanning electron microscopy (SEM). “Since [his] work … additional scientific approaches have been introduced including wet comb analysis, silicone deposition quantitation, fluorescence labeling, polymer dye techniques, head space analysis and spin coating.” Jordan added that new and novel polymers have been developed using these techniques to improve product performance.
“The consumer knows how a product feels on their hair, or if their hair looks frizzy. Scientists know parameters such as coefficient of friction, etc.” Jordan explained that these scientific parameters—such as changing polymer structures including charge density, hydrophobic character and molecular weight—can be changed to alter conditioning properties. In addition, increasing the molecular weight or charge density can increase the deposition of silicone. Coacervate formation also affects deposition on hair. And the introduction of additional polymers to hair also have profound effects on hair. These methods are what scientists need to fine tune to provide the end result the consumer senses. She concluded, “It has been a pleasure to be able to continue [Des’s] work.”
Modeling polycation surfactant complexes: Manuel Gamez-Garcia, PhD, of Ciba Corp., next examined the formation of polycation/surfactant complexes, which are used in 2-in-1 shampoo technologies. According to Gamex-Garcia, little is known about their structure, properties and modes of action. His work thus presented an analysis of key experimental observations to attempt to explain their mechanisms of action. His observations, including tests on a “dummy head” model, indicated that as with any cleansing system, the removal and deposition of actives on hair or scalp from shampoo result from the balance of hydrodynamic and double layer forces participating in the washing/deposition process.
“The cohesive and adhesion forces binding the polycationic/anionic surfactant complex to itself, to the droplets of particles, and to the hair surface should be able to withstand the hydrodynamic forces at the boundary layer at distances where the drag forces dominate,” wrote Gamez-Garcia in the meeting proceedings book. “Otherwise, complex particles and droplets will be removed.” He proposed that once the complex grows similar types of interactions producing a bridge between the hair surface, particles and droplets, that they will be able to resist the hydrodynamic drag at the boundary layer.
Improving tissue compatibility: Michael Fevola, PhD, of Johnson & Johnson presented the final paper of the morning session before the day two luncheon and business meeting. Fevola described polymer-surfactant association as a practical method to effectively reduce free micelle concentration. “Surfactants tend to penetrate into the tissue and cause damage to tissue structures, including disruption and disorganization of lipid bilayers and protein denaturation,” Fevola wrote. “This presentation will explain recent advances in understanding surfactant skin penetration, which have led us to employ polymer-surfactant association as a mechanism of mitigating surfactant irritation.
Successful irritation mitigation also requires hydrophobically-modified polymers (HMPs) with high surfactant binding efficacy. Fevola added that the use of HMPs in cleansing systems allows the formulator to attain new levels of mildness for enhanced consumer benefits—especially useful in the case of products for compromised skin, or for infant care.
Polymer-Surfactant Interaction—Fundamental Aspects
Part two of the Des Goddard tribute session opened with an introduction by Linda Rhein, PhD, then the past president of the SCC and most recently with Novartis and L’Oréal, of James Gruber, PhD, of Arch Personal Care, for his discussion on polyquaternium-10 in personal care.
PQ-10 and SLS: Gruber opened the afternoon discussion with a talk on polyquaterium-10 (PQ10) and SLS and their interaction with hair. According to Gruber, many methods have been developed in attempt to better understand the physical aspects of the coacervate that forms between PQ10 and SLS. The fundamental studies began with Des Goddard, who radiolabeled PQ10. Gruber wrote, “Coacervation helps to drive deposition of the cationic polymer/anionic surfactant complex into the hair, driving conditioning benefits to hair when delivered from an anionic shampoo.” In his research, Gruber studied the influence that molecular weight and cationic charge played on the cationic polymer itself, also via fluorescent tagging of the polymer. In addition, he developed a model in which macro-coacervates could be made by carefully blending 1% aqueous solutions of the cationic polymer with very low levels of SLS. Gruber closed with remarks about Des, recalling his welcoming attitude toward young scientists in personal care.
During the Q&A session, Meyer Rosen entertained attendees with a tale of Des Goddard finding ideas from a pet shampoo and incorporating them into personal care.
Anionic surfactant interactions and salt: Robert Lochhead, PhD, was up next and shared with attendees recollections of his work with Des. Lochhead presented his own famous work with phase diagrams and an animated salt shaker. Since the main theories of coacervate formation include a dependence on interactions between polymer and surfactant and hydrophobic associations between surfactant tail groups, the interference with these interactions would be expected to affect the coacervate formation: thus, enter Lochhead’s salt shaker. According to Lochhead, it generally is accepted that the addition of salt causes screening of either inter- or intramolecular interactions. Salts also have an effect on hydrophobic interactions. In the end, Lochhead concluded that the interactions between low charge substituted PQ10 and oppositely-charged surfactant are readily shielded by salt, whereas the interactions between high charge substituted PQ10 and oppositely charged surfactant persist and extend over a broader compositional range in the presence of salt, up to 130 mM. In the end, Lochhead graciously acknowledged the work of his student, Lisa Gandolfini, especially for having to prepare all the samples that were tested.
Polymer control of surfactant mesophases, liposomes: Following Lochhead, Robert K. Prud’homme, PhD, of the department of chemical engineering at Princeton, considered three systems for fine-tuning properties that are applicable in personal care: concentrated surfactant lamellar phases, rodlike micelle phases, and liposomes. In the case of hydrophobically modified polymer/lamellar surfactant systems, Prud’homme found that it is possible to create shear-induced “onions” which are attractive as potential delivery vehicles—especially suited for pharmaceuticals. Rodlike micelle phases, according to Prud’homme, affect solution viscosities based on whether they are the dominant phase or the polymer chains; if the rods are in the overlapping regime and the polymers are dilute, the polymers stitch together the rods and create a network with longer relaxation times and higher viscosities. Speaking to the topic of vesicles and liposomes, Prud’homme noted that hydrophobic polymers anchored on the surfaces of liposomes can be used either to protect liposomes from fusion or to create fluid gels. In closing, he thanked the organizers and said he was “honored” to present at Des’s session.
Sulfopolyester properties and applications: Next up was James McCaulley, PhD, of Eastman Chemical Co., who described water-dispersible sulfopolyesters—low molecular weight, aromatic copolyesters that contain random sulfonate groups. According to McCaulley, a broad range of properties is achieved by varying their composition and structure. He provided an overview of these compositions and described how their unique combination of properties determine their performance as functional film formers in a variety of personal care applications. Two important differences they offer are their exceedingly small particle size and effective plasticization by water. These differences are said to facilitate deformation and coalescence of the film. In the end, McCaulley noted these molecules offer great latitude in tailoring polymer properties to many cosmetic applications.
Lipid unsaturation, membrane protein and gel phase of mixed phospholipids: Finally, John W. Jones, PhD, of SCEAS and the University of Manchester, rounded out the scientific talks. According to Jones, glycerophospholipids have long been used in emulsification and encapsulation technologies and they are useful when a product is designed for in vivo or topical applications. Being natural, the materials are finding heavy used in cosmetics and drug delivery applications; however, little is known about the mechanism of phase transition of pure lecithin, and the phase diagram of the system is poorly understood. In the presented study, Jones and colleagues examined a mixed lecithin system containing both saturated and unsaturated chains and investigated the effect of a well-studies membrane protein, diacylglycerol kinase (DGK) on the phase behavior of the bilipids. He concluded that the membrane lipid appears to promote the fluidity within the bilayer, accelerating the lipid relaxation to the final equilibrium volume. Jones believes that the membrane protein regulates the packing of the lipid in the head group region. He adds that the phenomena represented by his studies have implications for the behavior of lipid liposomes as an encapsulation technology, and for drug transport across the lipid boundary.