Table 2.

Some plasmonic immunosensors developed for veterinary control applications of various β2-agonists i.e. clenbuterol, salbutamol, zilpaterol and ractopamine, in animal feedstuffs, and biological samples.

Sensing pathway	Transducer	LOD (ng/mL)	Linear range (ng/mL)	Analyte/sample	MRPLp (ng/mL)	Ref.
Direct immunoassaya	LSPR	20	50–800	MA/human urine	500	[103]
Direct immunoassayb	LSPR	10	20–800	Salbutamol/pig complex feed and pork liver	20	[104]
Antibody-based inhibitionc	SPR	10k	–	Clenbuterol/bovine hair	0.2	[105]
Indirect competitive immunoassayd	SPR	0.12	0.28–4.29	Ractopamine/pork liver	3	[106]
Antibody-based inhibitione	SPR	–	2–8	Zilpaterol/sheep urine	2	[107]
Competitive inhibition formatf	SPR	–	90–9325n 1.8–7515o	Ractopamine/sheep & Cattle urine	3	[108]
Competitive inhibition formatg	SPR	0.27	–	Clenbuterol/bovine urine	0.2	[109]
Indirect competitive inhibition immunoassayh	SPR	3 × 10−3	–	Clenbuterol/meat from food producing animals	0.2	[110]
Two different inhibition assays based on either immobilization of anti-clenbuterol or clenbuterol-BSAi	SPR	6.7 × 103l 4.5 × 103m	6.25 × 103–105	Clenbuterol	0.2	[111]
Competitive inhibition formatj	SPR	6.32 × 103	6.25 × 103–5 × 104	Clenbuterol	0.2	[112]

^aAntibody specific for salbutamol was immobilized on hollow gold nanoparticles (HGNs), which were deposited on transparent indium tin oxide (ITO) film.

^bSalbutamol specific antibodies were immobilized on triangular silver nanoparticles deposited on transparent ITO film on glass.

^cCM5 chip surface was coated with clenbuterol and first antibody and second antibody were sequentially applied.

^dRactopamine–ovalbumin (RCT–OVA) conjugate was immobilized onto an Au-thiolate sensor chip and the antigen (ractopamine) was detected upon adding the antibody.

^eCM-5 sensor chip was used to immobilize zilpaterol conjugate and the antibody was added.

^fThe antibody is bound to the ractopamine derivative immobilized on the sensor chip.

^gClenbuterol antibody was added to capture the drug stabilized on the sensor chip surface.

^hClenbuterol was immobilized on the surface treated with succinimidyl-modified propanethiol monolayer on a gold chip.

ⁱ1) immobilization of anti-clenbuterol antibody on the sensor chip as a probe (the target site compensation method) 2) immobilization of clenbuterol-BSA conjugate on the sensor chip with a competition assay.

^jSensing surface modified with 3D bioprobe consisting of BSA-CLEN conjugate.

^kng/g hair.

^lFor target site compensation method.

^mFor the solution competition method.

ⁿFor sheep urine.

^oFor cattle urine.

^pWADA general Minimum Required Performance Limit (MRPL) values.