The story behind the story of Avitene - ACS Publications

These crystals which are held together in the matrix are unhinged by chemical and mechanical means. The freed crystals can then act as single units, a...
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JOHN H. WOTlZ Southern Illinoh University

The Story Behind the Story of Avitene J e a n Bernius Alcon Laboratories 6201 S. Freeway Fort Worth, Texas 76101 What is white, fluffy, like a pile of whipped cream cheese, and the most hydrophilic polymer known to man? Avitene-it can absorb 99.75% water. Avitene is a n entirely new form of natural collagen. In its gel form, it is a water dispersion of collagen microcrystals. The polymer molecules are allowed to fall out of solution from a molten state to form crystals of a predetermined size. These crystals which are held together in the matrix are unhinged by chemical and mechanical means. The freed crystals can then act as single units, allowing interaction of surface colloidal forces. Highly viscous gels are formed as each tiny crystal picks up an envelope of water.' Dr. 0. A. Battista designed the process for making Avitene in 1955. He had been working with rayon to make a tougher tire. As he looked out the window, an assistant whirled some rayon and acid in a blender. The result was a white fluffy mess. The assistant was disgusted; he was elated. It was a brand new form of rayon. The tires idea was abandoned and Dr. Battista tried out his process on other synthetic and natural polymers. He made a dispersion of cellulose, added some salt and carotene, molded it, and brought home the first no-calorie butter to his wife. Though this no-cal butter would not add pounds, it would not melt, it would not do anything. As a butter it failed, hut its inability to liquefy with heat was a real advantage. As Avicel, to date, 120 million pounds have been sold for use as bulk in low-calorie foods, and for food stabilization. With Avicel added, foods like tuna fish salad, cream sauce, and salad dressing can he sterilized in their containers without separation or running. About ten years ago Dr. Battista discovered a use for Avitene. He cut himself shaving one morning, slapped a little Avitene on the cut, and the bleeding stopped painlessly. After years of inhouse work and clinical testing, a New Drug Application has been filed with the FDA for Micrystat, that is, Avitene for use as a hemostatic agent. Avitene controls bleeding by activating the natural blood coagulation p r o c e s s e ~ . ~ In 1969, Dr. Battista received the ACS Chemical Pioneer Award, and in 1971, the Captain of Achievement for his work in microcrystalline colloidal polymer chemistry. He was the 1973 recipient of the James T. Grady award for interpreting chemistry to the public. He recently retired from position as vice president of science and technology Avicon, Inc., Fort Worth, Texas, and will continue his work as a science writer.

' Battista, 0. A., Am. Scientist, 53, 151 (1965).

Battista, 0. A,, Erdi, N. Z., Ferraro, C. F., and Karasinski, d., J. A D D ~Polvrn. Sc.. 11. 481 (19671. . . Merritt. R. H.. Robb. C. A.. ~axie'r,C. R., ~orgrnann,A. R.. and ~ippktt,L. '0.. A;. J. o i 2

Surgen. 125.284


Frederick Augustus Genth and the Discovery of Cobalt-Ammines George B. Kauffman California State University, Fresno Fresno, 93740 Different historians ascribe different dates to the discovery of the first coordination compound. If we limit ourselves to the ammines of cohalt(III), the question of priority receives a more definitive answer. Most historians attribute the first observation of a cobalt-ammine to an otherwise unknown "Citizen" Tassaert, who in I798 described the analysis of a cohalt ore and mentioned the change in color on addition of ammonia to a cobalt solution ( I ) . Tassaert did not follow up his accidental discovery or isolate the hexaamminecobalt(III) compound formed. Credit for "the first distinct recognition of the existence of perfectly well-defined and crystallized salts of cobalt-ammonia bases" belongs to the German-American chemist and mineralogist Frederick Augustus Genth (1820-93) f2), who later collaborated with another American chemist, Oliver Wolcott Gihhs (1822-1908). In 1847, while he was Robert Bunsen's assistant a t the Universitat Marburg and during Bunsen's absence in Iceland, Genth obtained his first results on the cobalt-ammines. The "story behind the story" of his discovery, almost a case study of serendipity, was passed by oral tradition from Geuth to Edgar Fahs Smith to Thomas P. McCutcheou to Louis C. W. Baker, the latter two of whom were my instructors in general chemistry a t the University of Pennsylvania. Genth was instructing students in qualitative analysis by demonstration. Immediately before vacation, possibly Christmas, he had just removed the precipitated metals of Analytical Group ll by filtration from acidic solution and was about to make the solution basic with potassium hydroxide solution before resaturating with hydrogen sulfide. Since the demonstration laboratory had run out of potassium hydroxide, Genth substituted ammonia water ("spirits of hartshorn"), hut he had no time to resaturate the basic solution with hydrogen sulfide, so he put it aside. After vacation he found larae, beautiful. colored. inex~licablecrvstals. Careful repections of theprocedu;e, with exposureof the ammonia-containing cobalt solutions to air. but with varying conditions, enabled Genth to prepare several different types of crystals (3). He communicated his results to others and deposited samples of the salts in the lahoratory a t the University of Giessen.' Before Genth was able to complete his research on and analyses of these new compounds, he emigrated to the United States. Thus he did not publish his results until January, 1851 as "Vorlaufige Notiz uber gepaarte Kohaltverbindungen" in an obscure German language journal ~ u h l i s h e din Philadel~hia141. Here he described salts of (aquopentaamminecohalt(III)) two bases-roseocobalt salts and luteocohalt (hexaamminecobalt(II1)) salts. According to Gihhs and Genth, "though the analyses here given were from necessity not sufficiently complete and Volume 52, Nurnber3, March 7975