Table 7.

Biomaterial passport: spongin.

Scientific Name	Spongin
Chemical structure	Spongin is a collagen derivative protein which can be referred to halogenated scleroproteins or neurokeratin-like proteins [231,232]. However, halogens (I, Br), detected within spongin structure, do not occur in collagens or keratins [232]. The biochemistry of spongin as well as its molecular weight remains to be unknown.
Physicochemical properties	Spongin is not soluble neither by proteases (collagenase, pepsin, trypsin, amylase, lysozyme), nor by aggressive reagents, i.e., HCl, sulfuric acid, hydrogen peroxide [233,234,235]. Treatment with alkalis dissolves spongin resulting in hydrolysates of amino acids. In the natural habitat of sponges, spongin can be destroyed by bacteria and fungi [235]. Its thermostability is species dependent and ranges between 150 °C and 360 °C [236]. Owing to spongin, the scaffolds of bath sponge Spongia officinalis are characterized by unique material properties, such as the ability to hold water, toughness, compressibility and resiliency [232]. Heating of spongin scaffolds up to 1200 °C under exclusion of oxygen leads to obtaining of turbostratic graphite [86].
Spongin extraction/Physical form after extraction	Spongin skeletons can be purified using 3M HCl as was shown for Hippospongia communis [237].
Biomaterials properties (biocompatibility, biodegradability, toxicity, immune responses)	Spongin was reported to be biocompatible, biodegradable, non-toxic and of low immunogenicity [4,232,238,239].
Market situation (world market reports)	According to Technavio report, global commercial sponge market is predicted to reach USD 3.18 billion during 2020–2024 [240]. In addition, sponges can be cultivated and such sponge farms already exist in Japan, France, Greece, the Philippines, Micronesia, Australia, New Zealand, and East Africa [232].
Patents	Currently, about several hundreds of patents on sponge cultivation, sponge scaffolds extraction, their treatments, and applications exist.
	For search, use: https://patents.google.com/
	Selected examples:
	WO2015151030A1. Method to obtain collagen/gelatin from marine sponges
	WO2006089660A2. Method for cleaning marine collagen and the treatment thereof to form porous sponges
	US20030032601A1. Method for isolating sponge collagen and producing nanoparticulate collagen, and the use thereof
	US20080261876A1. Method for purifying marine collagen and the processing thereof into porous sponges
	US20100260823A1. Preparation with marine collagen for protease inhibition
	JPH07100B2. Method of drying collagen sponge
	DE10010113A. Native sponge collagen, process for its isolation and its use, as well as native nanoparticulate sponge collagen, process for its preparation and its use