Table 6. Activated UCNPs with Application in Sensing and/or Conjugation with Biomolecules.

s. no.	surface modification	materials used	synthesis method	particle size	application	ref
1	NaYF4:Yb,Er	streptavidin			DNA sensor	(87)
2	NaYF4:Yb,Er@SiO2	amino group		30 nm	delivery of siRNA	(84)
3	NaYF4:Yb,Tm@SiO2	PEG spacer carrying NHS groups	reverse microemulsion method	38 nm	protein conjugation	(88)
4	NaYF4:Yb,Er@SiO2	amino-ethoxy silane		50 nm	bioimaging and conjugate with biomolecules	(89)
5	NaYF4:Yb,Er@SiO2	antibody	glutaraldehyde spacer method		bioimaging and conjugate with biomolecules	(89)
6	NaYF4:Yb,Er@SiO2	anti-Cx43	glutaraldehyde spacer method		bioimaging and conjugate with biomolecules	(89)
7	NaYF4:Yb,Er	Fe3O4		100–150 nm	biolabeling, imaging of cancer cells, and conjugation with biomolecules	(85)
8	NaYF4:Yb,Er@SiO2@Ag	DNA	reverse microemulsion process		conjugate with DNA and cell imaging	(86)