Table 3.

Recently published techniques for sensitive detection of interleukin 6 with immuno-LFAs

Detection method	LOD	Matrix	Special remarks	Ref
Fluorescence (Eu-NPa)	0.37 pg mL−1	Buffer, human serum	70 µL sample LFA run 15 min, commercial strip reader	[19]
Fluorescence Quantum dots (QD)	100 pM (2.1 ng mL−1)b	Buffer, 10% serum	LFA run 20 min 100 µL sample, multiplex, protype detector with UV-LED	[20]
Photon-upconverion (UCP)c	n. a	Diluted whole blood	50-fold diluted benchtop reader, UPCON, Labrox	[21]
SERSd Au/Au core satellite nanoparticelse	n. a	PBS	Proof of principle, multiplex, non-commercial portable SERS reader	[22]
Fluorescence (fluorescent microspheresf)	7.15 pg mL−1 48.5 pg mL−1	Human plasma, hydrogel samples	Up to 33 µL, extra washing steps, commercial strip reader	[23]
Fluorescence (Near-infrared dyeg)	4 pg mL−1 (182 fmol L−1)	10% human plasma	75 µL sample, LFA run ≥ 15 min, benchtop image scanner	[24]
Fluorescence Quantum dots (QD)	4.5 pM (0.09 ng mL−1)	Buffer, 10% human serum	120 µL sample, LFA run 20 min benchtop image scanner	[25]
Photometry (commercial colloidal gold)	0.025 ng mL−1 (buffer) 0.081 ng mL−1 (HS)	Buffer, 100% human serum (HS)	36 µL sample LFA run 15 min, commercial strip reader	This work
Photometry (dye-loaded liposomes)	1 pg mL−1 (buffer) 7 pg mL−1 (HS)	Buffer, 100% human serum (HS)	36 µL sample LFA run 15 min, commercial strip reader	This work

^aEuropium(III) chelate–doped nanoparticles; ^bmolecular weight of 21 kDa for IL-6 was presumed; ^cup-converting phosphor nanoparticles; ^dsurface enhanced Raman scattering: ^ecore functionalized with Raman-active 4-nitrothiophenol for IL-6 or thio-2-naphthol for IL-8; ^fFluoSpheres®; fluorophore-doped particles (200 nm); ^gIRDye 800CW (Li-Cor Biosciences)