Biocompatible photoresponsive materials are of interest for targeted drug delivery, tissue engineering, 2D and 3D protein patterning, and other biomedical applications. We prepared light degradable hydrogels using a natural alginate polysaccharide cross-linked with iron(III) cations. The "hard" iron(III) cations used to cross-link the alginate hydrogel were found to undergo facile photoreduction to "soft" iron(II) cations in the presence of millimolar concentrations of sodium lactate. The "soft" iron(II) cations have a decreased ability to cross-link the alginate which results in dissolution of the hydrogel and the formation of a homogeneous solution. The photodegradation is done using long wave UV or visible light at neutral pH. The very mild conditions required for the photodegradation and the high rate at which it occurs suggest applications for iron(III) cross-linked alginate hydrogels as light-controlled biocompatible scaffolds.

Iron(III) cross-linked alginate hydrogel incorporating sodium lactate undergoes photoinduced degradation, thus serving as a biocompatible positive photoresist suitable for photochemical patterning. Alternatively, surface etching of iron(III) cross-linked hydrogel contacting lactic acid solution can be used for controlling the thickness of the photochemical pattering. Due to biocompatibility, both of these approaches appear potentially useful for advanced manipulation with cell cultures including growing cells on the surface or entrapping them within the hydrogel.

Background The Food and Drug Administration (FDA)-approved submucosal injection of lifting agents such as ORISE ® has become a widespread, routine and standard practice in endoscopic mucosal resection and endoscopic submucosal dissection of gastrointestinal lesions. Lifting agent granulomas result from transformation of injected material into a mass-forming amorphous hyaline-like material eliciting a strong foreign body giant cell reaction. This report of three cases shows how lifting agent granulomas can act as potential clinical and gross mimickers of invasive adenocarcinoma. Cases Description Three cases were identified in a six-month span based on the histological presence of a lifting agent granuloma in a colonic/colorectal resection specimen with associated clinical, imaging and gross concern for invasive malignancy. Each case resulted in an escalation of clinical and surgical management due to the suspicion of an unresectable neoplastic process that was at least partially involved by an exuberant granulomatous reaction due to the utilization of a lifting agent. Colonic transmural involvement and sub-serosal vascular infiltration by the granulomas are described. Conclusions Lifting agent granulomas have become a routine endoscopic technique to help achieve full resection of flat/sessile colorectal polyps and early-stage cancers. This report confirms that these granulomas exhibit colonic transmural involvement. Sub-serosal blood vessel involvement is reported for the first time. It is important to recognize the unique characteristics of these new synthetic lifting agents. Their propensity to develop a mass-forming granulomatous reaction has the potential to mimic invasive adenocarcinoma clinically, radiologically and pathologically. This can significantly impact patient care and management both clinically and surgically.

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