Soft matter implants are a rapidly growing field in medicine for reconstructive surgery, aesthetic treatments, and regenerative medicine. Though these procedures are efficacious, all implants carry risks associated with microbial infection which are often aggressive. Preventative and responsive measures exist but are limited in applicability to soft materials. Photodynamic therapy (PDT) presents a means to perform safe and effective antimicrobial treatments in proximity to soft implants. HEMA‐DMAEMA hydrogels are prepared with the photosensitizer methylene blue included at 10 and 100 µM in solution used for swelling over 2 or 4 days. Thirty minutes or 5 h of LED illumination at is then used for PDT‐induced generation of reactive oxygen species in direct contact with hydrogels to test viable limits of treatment. Frequency sweep rheological measurements reveal minimal overall changes in terms of loss modulus and loss factor but a statistically significant drop in storage modulus for some PDT doses, though within the range of controls and biological variation. These mild impacts suggest the feasibility of PDT application for infection clearing in proximity to soft implants. Future investigation with additional hydrogel varieties and current implant models will further detail the safety of PDT in implant applications.

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Implant infections pose a serious health risk to patients, both immediately after surgery and even years later. Hard materials provide the opportunity for more potent infection clearing, but soft materials like hydrogels are more delicate and may be more susceptible to the formation of sturdy bacterial biofilms. Photodynamic therapy (PDT) is a proven technique for infectious load reduction, biofilm penetration, and sensitization to antibiotic therapies. However, evaluation is lacking in efficacy of PDT in proximity to hydrogels, based on the risks of oxidative degradation. This preliminary study assesses the effects of PDT on HEMA-DMAEMA hydrogel viscoelastic properties. PDT is applied by soaking of hydrogels in PBS containing 10 μM methylene blue and subsequent 660 nm light exposure at 9.20 𝑚𝑊/𝑐𝑚2 for 30 minutes. PDT and all component controls cause reduction in values of storage modulus, loss modulus, and loss factor, but only differences in storage modulus are statistically significant as compared to baseline controls. Additionally, PDT component controls are comparable to the PDT test group, implying that photosensitizer integration and light degradation of hydrogels may be the primary source of interference. Overall, the changes noted in viscoelasticity are moderate and encourage further exploration with larger PDT doses, greater sample numbers, and testing of commercially available implant materials.