TABLE 2.

Some top keywords in terms of frequency and centrality.

Rank	Keywords	Count	Keywords	Centrality
1	drug delivery	379	polymer	.12
2	nanocomposite hydrogel	293	nanocomposite hydrogel	.09
3	nanoparticle	144	nanoparticle	.09
4	release	121	drug delivery system	.09
5	controlled release	70	release	.08
6	chitason	64	behavior	.08
7	behavior	60	delivery	.08
8	composite	59	acid	.08
9	graphene oxide	57	controlled release	.07
10	mechanical property	57	mechanical property	.07