Table 1.

Typical applications of gold nanoparticle-based colorimetric and electrochemical sensors for the detection of illegal food additives.

Sample source	Adulterant	Biosensors	Nanomaterials	Concentration range	Detection limit	Pretreatment to real samples	Ref.
infant formula	melamine	colorimetric	bare GNPs	5.0 × 10−6 2.0 × 10−4 g/L	2.0 × 10−7 g/L	precipitate proteins by trichloroacetic solution, then collect the supernatant	[17]
milk	melamine	colorimetric	1,4-dithiothreitol modified GNPs	8.0 × 10−8 6.0 × 10−7 M; 6.0 × 10−7 1.5 × 10−6 M	2.4 × 10−8 M	dilute 1000 times with distilled water	[19]
processed raw milk	melamine	colorimetric	asymmetrically PEGylated GNPs	1.05 × 10−3 −1.00 × 103 μmol/L	1.05 × 10−3 μmol/L	precipitate proteins with 10% trichloroacetic acid and acetonitrile, then sonicate, centrifuge, and filtrate	[21]
liquid milk	melamine	colorimetric	methanobactin-mediated synthesis of GNPs	3.90 × 10−7 −3.97 × 10−6 mol/L	2.38 × 10−7 mol/L	precipitate proteins with 10% trichloroacetic acid, then shake, centrifuge, and filtrate	[22]
food contact materials (plate or fruit tray)	melamine	electrochemical	GNPs/RGO/GCE	5–50 nmol/L	1.0 nmol/L	immerse in food simulants (water or 3% acetic acid) then heat and filtrate	[23]
ketchup and chilly sauce	Sudan I	electrochemical	GNPs/GCE	4.0 × 10−5 −1 × 10−3; 2 × 10−5 −7 × 10−7 mol/L	1.0 × 10−8 mol/L	ultrasonic extraction with ethanol and filtrate	[31]
chili and ketchup sauce	Sudan II	electrochemical	treated pencilgraphite electrode with DNA, o-phenylenediamine, and GNP bioimprinted polymer	1.0–20.0; 20.0 −500.0 nmol/L	0.3 nmol/L	ultrasonic extraction with ethanol and filtrate	[32]
chilli powder and ketchup sauce	Sudan I	electrochemical	GNPs/RGO/GCE	0.01–70 μmol/L	1 nmol/L	ultrasonic extraction with ethanol and filtrate	[37]
chopped red chili, tomato sauce; the apple juice and grape juice	Sudan I	electrochemical	ILRGO@GNPs/GCE	1.0 × 10−10 −1.0 × 10−6 mol/L	5.0 × 10−11 mol/L	for chopped red chili and tomato sauce, ultrasonic extraction with ethanol and filtrate; for the apple juice and grape juice, use directly without pretreatment	[39]
beef	ractopamine	colorimetric	Apt–GNPs	0–400 ng/mL	10 ng/g	homogenize with acetate ammonium buffer (pH = 5.2), then enzymatically digest, centrifuge and filtrate	[56]
pork	clenbuterol	electrochemical	MoS2–Au-PEI-hemin/GCE	0.01–2 μg/mL	0.00192 μg/mL	homogenize with 0.1 M HClO4 solution, then sonicate and centrifuge	[57]
meat products including ham sausage and red-braised pork	nitrite	colorimetric/fluorescent/SERS triple sensing	GNRs-Azo-GNPs	0.5–100 μmol/L	0.05 μmol/L	cut into 1 cm disk and 2 × 2 cm square piece	[65]
sausages	nitrite	colorimetric	Janus PEGylated GNP probe	10.8–174 μmol/L	10.8 μmol/L	shred, then dissolve with a saturated boric acid solution	[66]
packaged drinking water, processed meats and aquatic products	nitrite	electrochemical	ERGO/GNPs/SPCE	1–6000 μmol/L	0.13 μmol/L	homogenize, then ultrasonication, heat, cool to room temperature, filtrate, centrifuge and filtrate again	[68]
sausage	nitrite	electrochemical	GNP/p-ATP-modified gold electrode	0.5–50 mg/L	2.6 μmol/L	shred, add saturated borax solution, heat, precipitate proteins with 30% ZnSO4 solution, centrifuge and filtrate	[69]
pickled radish	nitrite	electrochemical	GNPs/GO-SH nanocomposites	5–1000 μmol/L	0.25 μmol/L	flush with ultrapure water, then squeeze into juice, ultrasonic treatment, heat and filtrate	[70]
milk	urea	colorimetric	GNPs–aptamer	20–150 mmol/L	20 mmol/L	precipitate proteins with methanol, vortex and centrifuge	[72]
milk	anionic detergents	colorimetric	bare GNPs	92–900 μg/mL	92 μg/mL	precipitate proteins using ice-cold methanol supplemented with NaCl, then vortex and centrifuge	[73]
fish	formalin	electrochemical	FDH/GNPs/[EMIM][Otf]/CHIT/GCE	0.01–10 ppm	0.1 ppm	thawed, then select the flesh to cut into small pieces, homogenize with Tris–HCl (pH 7, 0.5 M) and filtrate	[76]