Abstract: The present disclosure relates to a solution comprising a water insoluble carbohydrate and a fluorescent dye, such as a near infrared (NIR) contrast agent, wherein the solution sets under aqueous conditions, such as in vivo, to form e.g. a gel, a glass, a semi-solid, a solid, a crystal or any mixtures thereof. The disclosure further relates to preparation of such solution and use of such solution for in vivo imaging and/or guidance of surgery or interventional therapeutic procedures.