Deproteinization of Natural Rubber Latex and Its Pale-Colored Thin Films

Abstract

The non-rubber components present in natural rubber latex can contribute to the dark color of dried films and may cause allergic reactions. This project aimed to develop light-color rubber films with minimal protein contamination. Various additives were incorporated, and a leaching procedure was implemented to address this issue. The evaluation focused on protein content, color changes, and swelling properties of thin natural rubber films. Texapon N70 proved effective as both a latex stabilizer and leaching agent, while Uniphen P-23 served as a preservative. The combined use of these additives facilitated the removal of soluble serum through appropriate incubation, leaching, and centrifugation processes. The introduction of additional centrifugation cycles improved deproteinization and color reduction; however, it led to a loss of rubber mass and an increase in manufacturing costs. Increasing the amount of Texapon N70 and introducing alkali potassium hydroxide (KOH) further enhanced the efficiency of deproteinization and color reduction. The optimal conditions determined in this investigation were as follows: 0.5% w/w Texapon N70, 0.5% w/w KOH, 1% w/w Uniphen P-23, a 60-min incubation period, and a single leaching cycle with distilled water. These conditions resulted in a 90.57 ± 1.20% decrease in protein contamination and a color change (ΔE) of 433.69 ± 20.23. This successful condition can be replicated and scaled up for further applications.

Porous Deproteinized Natural Rubber Film Loaded with Silver Nanoparticles for Topical Drug Delivery

“…As previously mentioned, deproteinized natural rubber latex was made in-house using an enzyme treatment and centrifugation technique that was safe for skin contact [16][17][18]. In brief, fresh natural rubber was deproteinized with 0.2 parts of alcalase enzyme per hundred of rubber, control pH 7-8 with 0.01 N sodium hydroxide solution, 1% w/v sodium dodecyl sulfate as a stabilizer, and 2% w/v Uniphen P-23 as a preservative and incubated for 48 h at 37 ± 2 • C. The washed natural rubber latex was centrifuged to separate it, then it was redistributed in distilled water and stored in the refrigerator at about 4 • C until it was used.…”

“…During the manufacturing process of the deproteinized natural rubber latex, the pH was adjusted to 7-8 using a 0.01 N sodium hydroxide solution because this pH value is most effective for the process of alcalase enzyme digesting proteins in natural rubber latex [16][17][18]. Consequently, when the deproteinized natural rubber latex was produced as a film, the prepared film's surface pH was 7.22 ± 0.06.…”