Seven-day controlled silver-ion release

For an antimicrobial silver surface, the central question is not only how much silver it contains. The useful questions are: in what form is the silver present, how do ions become available in the contact environment, and how is that availability managed across the use period? Lunwell’s seven-day technology addresses all three within one design window.

1. From metallic surface to Ag⁺ ion

Surface reactions begin when the elemental-silver coating contacts wound fluid. A small fraction becomes bioavailable as positively charged Ag⁺ ions. This ionic form binds to bacterial membranes, proteins and energy systems. The coating functions as the surface reservoir that supplies ions across the use period.

2. Why controlled release?

Availability distributed across the use window supports continuity of the antimicrobial surface without relying on a single high release. Lunwell’s design dossier specifies a product acceptance criterion of <10 ppm for silver release and a seven-day antimicrobial-barrier effect. Together these criteria describe the engineering balance between ionic activity at the surface and controlled total exposure.

3. How was the seven-day test designed?

In the 2026 chemical characterisation, the largest 10 × 30 cm model was selected as the worst-case device. To reflect normal clinical use and silver release for up to seven days, samples were extracted in water and hexane for seven days at 37 ± 1 °C. Inorganic constituents were analysed by ICP-MS, while surface and potential particle release were examined with complementary methods including ATR-FTIR and SEM-EDX.

4. Measured results

• Ag concentration was measured at 1013.1 ± 123.5 ng/mL.
• Total extracted silver was calculated as 7.55 µg per 10 × 30 cm device.
• The value remained below the report’s analytical evaluation threshold.
• In the Ag-specific assessment, the margin of safety remained above 1 across all evaluated contact durations and toxicological risk was concluded to be tolerable.
• No nanoscale silver-particle release was detected under the applied test conditions.

These results clarify the distinction between surface nanotechnology and the released species: the material architecture is silver-coated, while the antimicrobial form measured in the contact environment is ionic silver.

5. What does seven days mean in clinical use?

Seven days is the period for which Lunwell’s antimicrobial barrier is designed. It does not mean every wound is left without assessment for exactly seven days. Wound condition, exudate level, secondary-dressing capacity and clinical monitoring determine change timing. In appropriate conditions, Lunwell may remain in place as the wound-contact layer for up to seven days.

6. Why the complete dressing system matters

Lunwell’s porous polyester architecture does not absorb exudate; it allows fluid to pass to the secondary dressing. Seven-day performance therefore gains its full meaning when the silver surface is combined with appropriate exudate management, a suitable secondary dressing and clinical monitoring.

Author: Lunwell Science Editorial Team