Characterization, optimization, and in vitro evaluation of Technetium-99m-labeled niosomes

Figures & data

Figure 1 Chemical structure of synthesized TPGS-DTPA.

Abbreviation: TPGS-DTPA, d-α-tocopherol polyethylene glycol 1000 succinate-diethylenetriaminepentaacetic acid.

Figure 2 FTIR spectra of DTPA anhydride, TPGS and synthesized TPGS-DTPA.

Abbreviations: DTPA, diethylenetriaminepentaacetic acid; FTIR, Fourier-transform infrared spectroscopy; TPGS, d-α-tocopherol polyethylene glycol 1000 succinate.

Figure 3 ¹H NMR spectra of (A) TPGS and (B) TPGS-DTPA synthesized via microwave technology.

Abbreviations: DTPA, diethylenetriaminepentaacetic acid; NMR, nuclear magnetic resonance; TPGS, d-α-tocopherol polyethylene glycol 1000 succinate.

Figure 4 ¹³C NMR spectra of (A) TPGS and (B) TPGS-DTPA synthesized via microwave technology.

Abbreviations: DTPA, diethylenetriaminepentaacetic acid; NMR, nuclear magnetic resonance; TPGS, d-α-tocopherol polyethylene glycol 1000 succinate.

Table 1 Formulation of niosomes (expressed as molar ratio) and their corresponding particle size, PDI, and zeta potential

Formulation	Span 60:cholesterol: TPGS-DTPA	Particle size (nm), mean ± SD	PDI, mean ± SD	Zeta potential, mean ± SD
N1	1:1:0.1	173.0±5.9*	0.232±0.028	−56.8±5.4
N2	1:1:0.2	142.2±6.9*	0.308±0.033	−58.3±2.3
N3	1:1:0.3	108.8±1.7	0.196±0.023	−61.8±2.9
N4	1:1:0.4	109.5±0.8	0.199±0.019	−65.3±4.8
N5	1:1:0.5	108.8±2.4	0.201±0.034	−69.5±3.4

Note:

* P<0.05, statistically significant (N1, N2, N4, N5 were compared with N3).

Abbreviations: DTPA, diethylenetriaminepentaacetic acid; PDI, polydispersity index; TPGS, d-α-tocopherol polyethylene glycol 1000 succinate.

Table 2 Radiolabeling efficiency of ^99mTc-labeled niosomes with increasing concentrations of TPGS-DTPA

Formulation	^99mTcO4^− (%)	Radiocolloids (%)	^99mTc-labeled niosomes (%)	Loaded amount of ^99mTc (mCi)
N1	5.14±1.15	17.71±1.85	77.16±0.87*	1.54±0.02
N2	5.86±0.47	5.99±1.87	88.15±2.01*	1.76±0.04
N3	5.99±1.95	2.13±0.34	91.88±1.64	1.84±0.03
N4	5.93±1.96	1.38±0.41	92.69±1.84	1.85±0.04
N5	5.85±0.63	1.54±0.36	92.62±0.90	1.85±0.02

Notes: Formulations N1–N5: SnCl₂·H₂O 30 µg/mL; pH 5; and incubation time 15 min. Data presented as mean ± SD.

* P<0.05, statistically significant (N1, N2, N4, N5 were compared with N3).

Abbreviations: DTPA, diethylenetriaminepentaacetic acid; SnCl₂·H₂O, stannous chloride; ^99mTc, Technetium-99m; TPGS, d-α-tocopherol polyethylene glycol 1000 succinate.

Figure 5 TEM micrograph of niosomes (N3) at a magnification of 800×.

Abbreviation: TEM, transmission electron microscope.

Figure 6 TEM micrograph and measurement of a single niosome (N3) at a magnification of 25,000×.

Abbreviation: TEM, transmission electron microscope.

Table 3 The effect of varying concentrations of SnCl₂·H₂O on the radiolabeling efficiency of ^99mTc-labeled niosomes (N3)

Concentration of SnCl2·H2O (μg/mL)	^99mTcO4^− (%)	Radiocolloids (%)	^99mTc-labeled niosomes (%)	Loaded amount of ^99mTc (mCi)
10	5.10±0.22	1.39±0.20	93.50±0.38	1.87±0.01
^Citation20	2.13±0.27	1.82±0.07	96.05±0.26	1.92±0.01
30	1.59±0.22	1.03±0.04	97.38±0.25	1.95±0.01
^Citation40	1.62±0.06	2.28±0.13	96.10±0.15	1.92±0.003
50	1.05±0.20	5.34±0.12	93.61±0.14	1.87±0.002
60	1.17±0.12	7.67±0.30	91.16±0.42	1.82±0.01

Notes: Formulation N3: SnCl₂·H₂O 10–60 µg/mL; pH 5; and incubation time 15 min. Data presented as mean ± SD.

Abbreviations: SnCl₂·H₂O, stannous chloride; ^99mTc, Technetium-99m.

Table 4 The effect of varying pH on the radiolabeling efficiency of ^99mTc-labeled niosomes (N3)

pH	^99mTcO4^− (%)	Radiocolloids (%)	^99mTc-labeled niosomes (%)	Loaded amount of ^99mTc (mCi)
4	3.48±0.18	2.62±0.53	93.90±0.70	1.88±0.02
5	2.38±0.13	0.69±0.15	96.93±0.15	1.93±0.01
6	3.29±0.31	2.48±0.10	94.25±3.31	1.89±0.07
7	4.83±0.07	2.87±0.13	92.29±0.19	1.85±0.01
8	15.81±1.28	1.03±0.09	83.16±1.31	1.66±0.03

Notes: Formulation N3: SnCl₂·H₂O 30 µg/mL; pH 4–8; and incubation time 15 min. Data presented as mean ± SD.

Abbreviations: SnCl₂·H₂O, stannous chloride; ^99mTc, Technetium-99m.

Figure 7 The effect of incubation time on the radiolabeling efficiency of ^99mTc-labeled niosomes (N3).

Note: Data presented as mean ± SD.

Abbreviation: ^99mTc, Technetium-99m.

Figure 8 Stability of ^99mTc-labeled niosomes (N3) in saline and serum in vitro at 37°C.

Note: Data presented as mean ± SD. (n= mean ± SD).

Abbreviation: ^99mTc, Technetium-99m.

Figure S1 Full range FTIR spectra (400–4,000 cm⁻¹) of DTPA anhydride, TPGS, and synthesized TPGS-DTPA.

Abbreviations: DTPA, diethylenetriaminepentaacetic acid; FTIR, Fourier-transform infrared spectroscopy; TPGS, d-α-tocopherol polyethylene glycol 1000 succinate.

Figure S2 ¹H NMR spectrum (0–2.4 ppm) of TPGS.

Abbreviations: NMR, nuclear magnetic resonance; TPGS, d-α-tocopherol polyethylene glycol 1000 succinate.

Figure S3 ¹H NMR spectrum (2–4.4 ppm) of TPGS.

Abbreviations: NMR, nuclear magnetic resonance; TPGS, d-α-tocopherol polyethylene glycol 1000 succinate.

Figure S4 ¹H NMR spectrum (0–5 ppm) of synthesized TPGS-DTPA.

Abbreviations: NMR, nuclear magnetic resonance; TPGS-DTPA, d-α-tocopherol polyethylene glycol 1000 succinate-diethylenetriaminepentaacetic acid.

Figure S5 ¹³C NMR spectrum (0–180 ppm) of TPGS.

Abbreviations: NMR, nuclear magnetic resonance; TPGS, d-α-tocopherol polyethylene glycol 1000 succinate.

Figure S6 ¹³C NMR spectrum (0–180 ppm) of synthesized TPGS-DTPA.

Abbreviations: NMR, nuclear magnetic resonance; TPGS-DTPA, d-α-tocopherol polyethylene glycol 1000 succinate-diethylenetriaminepentaacetic acid.

Table S1 Effect of increasing probe sonication times on particle size and PDI of niosomes (N3)

Sonication time (minute)	Particle size (nm)	PDI
0	610.1±111.3	0.741±0.111
2	389.2±62.7	0.610±0.129
4	221.2±21.5	0.523±0.109
8	124.8±6.8	0.294±0.076
12	130.8±3.1	0.241±0.031

Abbreviation: PDI, polydispersity index.

Table S2 The effect of temperature on radiolabeling efficiency

Temperature (°C)	^99mTcO4^− (%)	Radiocolloids (%)	^99mTc-labeled niosomes (%)	Loaded amount of ^99mTc (mCi)
23	1.36±0.37	1.70±0.31	96.94±0.61	1.94±0.01
37	2.30±0.36	1.44±0.14	96.26±0.48	1.93±0.01

Notes: Formulation N3: SnCl₂·H₂O 30 µg/mL; pH 5; and incubation time 15 min.

Abbreviations: SnCl₂·H₂O, stannous chloride; ^99mTc, Technetium-99m.

Table S3 Effect of increasing probe sonication times on particle size and PDI of niosomes (N3)

Niosomes	Particle size (nm)	PDI	Zeta potential (mV)
Blank	129.1±3.7	0.193±0.011	−68.6±2.9
T3-loaded (15 mg/mL)	127.3±1.5	0.218±0.013	−67.2±3.6

Abbreviation: PDI, polydispersity index.

RichardsonVJJeyasinghKJewkesRFRymanBETattersallMHNProperties of [99mTc] Technetium-labelled liposomes in normal and tumour-bearing ratsBiochem Soc Trans197751290291892186

 PubMedGoogle Scholar

ChoNJHwangLYSolandtJJRFrankCWComparison of extruded and sonicated vesicles for planar bilayer self-assemblyMaterials2013683294330828811437

 PubMed Web of Science ®Google Scholar