Preparation and evaluation of tacrolimus-loaded thermosensitive solid lipid nanoparticles for improved dermal distribution

Figures & data

Table 1 Formulations of blank-SLNs

	Excipient	SLN-B1	SLN-B2	SLN-B3	SLN-B4	Solvent
Oil phase	Cocoglyceride	0.4 g	0.4 g	0.4 g	0.4 g	Methylene chloride
Lipid phase	Lecithin	0.3 g	0.3 g	0.3 g	0.3 g	Ethanol
Brij^® 93	1.0 g	1.0 g	1.0 g	1.0 g
Aqueous phase	Poloxamer 188	1.0 g	–	–	–	Distilled water
	PEG-40 stearate	–	1.0 g	–	–
	Brij^® 58	–	–	1.0g	–
	PEG-1000	–	–	–	1.0 g

Table 2 Formulations of TCR-SLNs

	Excipient	TCR-SLN-1	TCR-SLN-2	Solvent
Drug-oil phase	Coco glyceride	0.4 g	0.4 g	Methylene chloride
Tacrolimus	0.1 g	0.1 g
Lipid phase	Lecithin	0.3 g	0.3 g	Ethanol
Brij^® 93	1.0 g	1.0 g
Aqueous phase	Poloxamer 188	1.0 g	–	Distilled water
Brij^® 58	–	1.0 g

Table 3 Grading scale for the Draize test

Grade	Formation of erythema
0	No erythema
1	Very slight erythema
2	Well-defined erythema
3	Moderate to severe erythema
4	Severe erythema

Figure 1 DSC thermograms of: (A) the raw surfactant and blank SLNs prepared with surfactant; (B) the raw materials and prepared TCR-SLNs.

Table 4 Particle properties of TCR-SLNs (mean ± standard deviation)

	TCR-SLN-1	TCR-SLN-2
Mean particle size (nm)	152.9±4.09	143.1±7.98
Polydispersity index	0.25±0.03	0.27±0.02
Entrapment efficiency (%)	88.9±0.7	88.5±0.2

Figure 2 XRD patterns of the raw materials and prepared TCR-SLNs.

Figure 3 FT-IR spectra of the raw materials, prepared TCR-SLNs, and physical mixtures of TCR-SLN materials.

Figure 4 TEM images of TCR-SLNs dried at different temperatures (magnification: ×12,500, scale bar =500 nm).

Table 5 Amount of TCR accumulated in 24 h in the in vitro and ex vivo test conducted at 37 °C on TCR-SLNs stored at different temperatures for 2 h (mean ± standard error; *Student’s t-test, p-value <0.05 with TCR-SLN-2; **Student’s t-test, p-value <0.005 with TCR-SLN-2)

	Amount accumulated at 24 h after in vitro release test		Amount accumulated at 24 h after ex vivo skin deposition test
Storage temperature before test	TCR-SLN-1	TCR-SLN-2	TCR-SLN-1	TCR-SLN-2
25 °C	22.52% ±1.17%	20.11% ±0.82%	21.82% ±4.38%	8.31% ±1.26%
37 °C	29.00% ±2.26%*	37.80% ±2.08%	16.89% ±1.45%**	3.80% ±0.58%
50 °C	48.55% ±0.30%	46.96% ±1.10%	14.16% ±1.84%**	4.57% ±0.21%

Figure 5 FT-IR imaging of the stratum corneum and skin at different depths after ex vivo skin penetration test at 37 °C using the reference product and TCR-SLNs.

Figure 6 In vivo skin penetration test using reference product and TCR-SLN-1 (mean ± standard error; S.C.: stratum corneum, *Student’s t-test, p-value <0.05 compared with the reference product; **Student’s t-test, p-value <0.01 compared with the reference product).

Figure 7 FT-IR imaging of the stratum corneum and skin at different depths after in vivo skin penetration test using the reference product and TCR-SLN-1.

Table 6 Skin irritation test of the reference product and TCR-SLN-1 (mean ± standard error; **Student’s t-test, p-value <0.005 compared with the reference product)

	TCR-SLN-1	Reference product
Score	1.24±0.14**	2.71±0.07

Figure S1 Images of skin samples from each group (24h after drug application)