Table 1.

Summary of cross-linked gels and applications.

Class of Cross-Linked Gel	Advantages	Disadvantages	Applications	Ref
Emulgel	Thixotropic Easily spreadable Long shelf life Improved loading efficiency Great stability	Allergic reactions Poor permeability Contact dermatitis Not easily absorbed	Topical emulgel of mefenamic acid. Topical emulgel microemulsion	[34,36,37,39,40]
Organogel	Ease of preparation May be used for transdermal, oral, and parenteral. Non-irritating Good resistance to microbial contamination.	Lack of biocompatibility formulations. Poor stability to temperature Greasy in nature	Intraocular flunarizine hydrochloride-loaded organogel Biodegradables in-situ forming organogel.	[42,43,44,45]
Hydrogel	Capable of retaining a high amount of water Hydrophilicity Biocompatibility potential Controlled drug release Smart drug delivery	It may be difficult to handle It may be difficult to sterilize Usually mechanically weak.	Chemically cross-linked by glutaraldehyde for biomedical applications. Physically cross-linked hydrogel consisting of poly (acrylamide-co-acrylic acid) (PAM-co-PAA) and poly(vinyl alcohol) (PVA).	[43,45,62,63,64,65,66,67,68,69]
Aerogel	High porosity Low bulk density Exceptional textural features	Low mechanical strength High environmental and economic costs of operation	Incorporation of niacin/nicotinic acid and ibuprofen in an aerogel	[73,74]
Cryogels	Substantial pore size and porosity High water content Great pore connectivity and consistency Flexibility of preparation Economically and environmentally friendly	Insufficient retention at injection site. Injectable cryogels may cause serios side effects. Need for repeated injections Increased costs	Thermoresponsive cryogels containing oligoehylene glycol Polyacrylic acid cryogels as PH oscillatory bromate-sulphite ferrocynide processes.	[63,66,69]