Stable silk protein fragment compositions
A composition is disclosed that includes pure silk fibroin-based protein fragments that are substantially devoid of sericin, wherein the composition has an average weight average molecular weight ranging from about 17 kDa to about 38 kDa, wherein the composition has a polydispersity of between about 1.5 and about 3.0, wherein the composition is substantially homogeneous, wherein the composition between 0 ppm to about 500 ppm of inorganic residuals, and wherein the composition includes between 0 ppm to about 500 ppm of organic residuals.
1. A composition comprising:
pure silk fibroin-based protein fragments having about 0.01% (w/w) to about 10% (w/w) sericin, wherein the fragments have an average weight average molecular weight ranging from about 35 kDa to about 40 kDa, wherein the fragments have a polydispersity of from about 1.5 to about 3.0,
wherein the composition is substantially homogeneous,
wherein the composition includes between 0 ppm to 500 ppm of inorganic residuals,
where-in the composition includes between 0 ppm to 500 ppm of organic residuals, and
wherein the composition does not spontaneously or gradually gelate and does not visibly change in color or turbidity when in a solution for at least 10 days.
2. The composition of claim 1 wherein the inorganic residuals include lithium bromide and wherein the organic residuals include sodium carbonate.
3. The composition of claim 2 wherein the lithium bromide residuals are measurable using a high-performance liquid chromatography lithium bromide assay, and the sodium carbonate residuals are measurable using a high-performance liquid chromatography sodium carbonate assay.
4. The composition of claim 1 wherein the solution is an aqueous solution.
5. The composition of claim 1 in a sealed container.
6. The composition of claim 1 further comprising polyanhydrides.
7. The composition of claim 6 further comprising vitamin C or a derivative thereof.
8. The composition of claim 6 further comprising an alpha hydroxy acid selected from the group consisting of glycolic acid, lactic acid, tartaric acid and citric acid.
9. The composition of claim 6 further comprising hyaluronic acid or its salt form at a concentration of about 0.5 wt. % to about 10.0 wt. %.
10. The composition of claim 6 further comprising at least one of zinc oxide or titanium dioxide.
11. The composition of claim 1 wherein the pure silk fibroin-based protein fragments are hypoallergenic.
12. The composition of claim 1 having less than 10 colony forming units per gram.
13. The composition of claim 1 , wherein the composition does not spontaneously or gradually gelate and does not visibly change in color or turbidity when in a solution for at least 30 days.
14. The composition of claim 1 wherein the average weight average molecular weight range and the polydispersity are measurable using a high-performance liquid chromatography assay.