Grouping of nanomaterials to read-across hazard endpoints: from data collection to assessment of the grouping hypothesis by application of chemoinformatic techniques

Table 1 Physicochemical properties (“what they are”) of the source and target analogues [19, 23]

Property	NM-100	NM-101	NM-102	NM-103	NM-104	NM-105	TiO₂ R nano	TiO₂ A nano
Crystal type	Anatase	Anatase	Anatase	Rutile	Rutile	83% anatase 17% rutile	Rutile	Anatase
Total non-TiO₂ content including coating and impurities (% w/w)	1.5	9	5	11	11	0.11	13	0.50
Surface chemistry (as declared by manufacturer)^f	uncoated	uncoated	uncoated	Al₂O₃, (C₂H₆OSi)_nand C₆H₁₆O₂Si	Al₂O₃, (C₂H₆OSi)_nand C₃H₈O₃	uncoated	SiO₂ (< 5%) Na₂SO₄ \( {\mathrm{SO}}_4^{-2} \)	uncoated
Surface coating (% w/w)	0	0	0	8	8	0	11	0
Primary particle diameter (TEM) (nm)	93 ± 23	5 ± 1	22 ± 10	24 ± 2	24 ± 2	20 ± 3	10 nm diameter 62 nm length	14
Crystallite size (XRD) (nm)^a	117 ± 40	7 ± 2	24 ± 5	24 ± 4	25 ± 4	22 ± 5	–	–
Particle Size Distribution (nm)	210 ± 10^b	278^b	440 ± 37^b	135 ± 25^b	145 ± 35^b	177 ± 39^b	125^c	145^c
Shape	Spheroidal	Spheroidal	Spheroidal	Spheroidal	Spheroidal	Spheroidal	Rod	Sphere
Aspect ratio	1.53	1.53	1.53	1.7	1.53	1.36	–	–
Specific surface area (m²/g)	9^d	242 ± 73^d	77 ± 10^d	54 ± 4^d	54 ± 2^d	47 ± 0.5^d	177^e	149^e
Total pore volume (ml/g)	0.0324	0.319	0.2996	0.2616	0.1935	0.1937	–	–

^avalues averaged from different instruments and principles (Peak fit, TOPAS, Fullprof, Scherrer eq., TOPAS, IB, TOPAS FWHM)
^bvalue from DLS
^cvalues averaged from ICP-MS and DLS experiments
^dvalues averaged from SAXS/USAXS and BET
^evalue from BET
^f(C₂H₆OSi)_n indicates presence of dimethicone, C₆H₁₆O₂Si of dimethoxydimethylsilane, and C₃H₈O₃ of glycerol

ISSN: 1743-8977