In vitro testing of fluorescent emission showed the particles with the thinner coating were considerably more efficient, which is consistent with self-quenching reducing emission shown in the thicker ICG coatings. Conversely, for thicker walls on 2 μm diameter silica shells, the ICG layer was only bound to the outer surface and was 6 nm thick. For ultra-thin wall 100 nm diameter silica shells, a bimodal ICG layer of <3 nm is was formed. Using a positively charged amine linker, ICG was non-covalently adsorbed onto the nanoparticle surface. A novel infrared marker was developed using FDA approved indocyanine green (ICG) dye and ultrathin hollow silica nanoshells (ICG/HSS). However, non-fluorescent dyes such as India ink cannot be imaged below the tissue surface and there is evidence for physiological complications such as abscess, intestinal perforation and inconsistency of dye injection. Marking colon tumors for surgery is normally done with the use of India ink. Although tattooing is widely used and relatively safe, the presented case indicates the risk of infection or inflammation by tattooing.

Histologic examination of the edematous tattooing area revealed an ink abscess spreading laterally above the muscularis propria. The distal resection margin was extended approximately 5 cm more than expected because of long extent of edematous mucosa. During the laparoscopic operation, the proximal and distal margin of the lesion appeared edematous with bluish color. Authors encountered a case of a 60-year-old man with a resectable sigmoid colon cancer which was tattooed with India ink for subsequent localization in the intraoperative setting. Although the mechanism of complication is not completely understood, it may be related to the chemical compounds contained in the ink solution and enteric or extraenteric bacterial inoculation by injection needle or the ink itself. However, significant complications have been reported, including local inflammatory pseudotumor formation, peritonitis, rectus muscle abscess, small bowel infarction, and phlegmonous gastritis. Endoscopic tattooing with India ink is generally regarded as a safe procedure that enables ready identification of endoluminal cancer from the serosal surface.

India ink for tattoos