Light activated composite tissue adhesives

A composition, comprising:

• collagen, wherein the concentration of the collagen in the composition is from 300 mg/ml up to and including 800 mg/ml;
• and
• a chromophore that produces a reactive oxygen species upon exposure to electromagnetic radiation, wherein the concentration of the chromophore is substantially equal to 1.0% (w/v) to 2.0% (w/v), and wherein the chromophore is selected from the croup consisting of:
• riboflavin, luminflavin, and lumichrome.

A composition comprising:

• a first layer including:
• a first collagen, wherein the concentration of the first collagen in the first layer is from 300 mg/ml up to and including 800 mg/ml, and
• a first chromophore that produces a reactive oxygen species upon exposure to electromagnetic radiation, the first layer having been exposed to electromagnetic radiation having a wavelength in a range of 350-375 nm or 440-489 nm, wherein the concentration of the first chromophore is substantially equal to 1.0% (w/v) to 2.0% (w/v), and wherein the first chromophore is selected from the group consisting of:
• riboflavin, luminflavin, and lumichrome;
• and
• a second layer including:
• a second collagen, wherein the concentration of the second collagen in the second layer is from 300 mg/ml up to and including 800 mg/ml, and
• a second chromophore that produces a reactive oxygen species upon exposure to electromagnetic radiation.