The presence of residual gold nanoparticles in samples interferes with the RT-qPCR assay used for gene expression profiling

Table 8 Summarised results for the universal RNA standard spiked at the amplification step (part 2) during AuNP-interference assessment, using CFX Manager™ software

	18S	ACTB	GAPDH	GUSB	HPRT1	HSP90	PPI	SDH	TBP	YWHAZ
E (90 to 110%)^a	116 to 124.7	84.7 to *106.8*	84.2 to *98.2*	*108.8* to 117.5	*96.2* to *100.9*	*99.1* to *106.4*	*105.3* to 154.1	135.0 to 145.9	*105.6* to 364.8	*90.0* to *98.5*
R² (> 0.980)^b	*0.994* to *1.000*	0.961 to *0.998*	*0.995* to *1.000*	*0.986* to *1.000*	*0.990* to *1.000*	*0.995* to *1.000*	0.970 to *1.000*	0.956 to *0.994*	0.945 to *0.997*	*0.989* to *1.000*
Slope (− 3.1 to − 3.6)^a	− 2.845 to − 2.986	− *3.169* to − 3.751	− *3.365* to − 3.770	− 2.964 to − *3.129*	− *3.300* to − *3.416*	− *3.177* to − *3.343*	− 2.469 to − *3.200*	− 2.559 to − 2.695	− 1.499 to − *3.195*	− *3.358* to − *3.588*
NTC C_q	35.44 to 37.60	*N/A*	*N/A*	Peaks ^c	38.05	33.04 to 39.44	*N/A*	35.04	26.39 to 39.27	39.24

Bold italic acceptable result; italics unacceptable result
^aFor an PCR efficiency (E) of 100%, the slope is − 3.32. A good reaction should have an efficiency between 90 and 110%, which corresponds to a slope between − 3.58 and − 3.10
^bThe linearity of the assay (R²), where R² < 0.980 unacceptable; R² ≥ 0.980 acceptable; R² > 0.990 expected; R² > 0.995 exceptional
^cThe peaks had shoulders, i.e. indication of secondary structures within the molecule

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