Design and evaluation of an intravesical delivery system for superficial bladder cancer: preparation of gemcitabine HCl-loaded chitosan–thioglycolic acid nanoparticles and comparison of chitosan/poloxamer gels as carriers

Figures & data

Table 1 Particle size, polydispersity index, and zeta potential values of blank and Gem-HCl-loaded NPs (repeated n=6)

Formulation	Particle size (d·nm) ± SD	Polydispersity index ± SD	Zeta potential (mV) ± SD
Chitosan–TGA NPs	188.3±2.054	0.229±0.020	33.500±1.030
Gem-HCl-loaded chitosan–TGA NPs	174.5±3.762	0.239±0.012	32.100±0.575

Abbreviations: TGA, thioglycolic acid; NPs, nanoparticles; Gem-HCl, gemcitabine hydrochloride; SD, standard deviation.

Figure 1 Particle size distribution of blank and Gem-HCl-loaded NPs (repeated n=6).

Notes: Green line, blank NPs; red line, Gem-HCl-loaded NPs.

Abbreviations: Gem-HCl, gemcitabine hydrochloride; NP, nanoparticle.

Figure 2 SEM images of blank NPs and Gem-HCl loaded chitosan–TGA NPs.

Notes: Magnification ×25,000 (A and C); magnification ×50,000 (B and D).

Abbreviations: SEM, scanning electron microscopy; TGA, thioglycolic acid; NP, nanoparticle; Gem-HCl, gemcitabine hydrochloride.

Table 2 Viscosity values of chitosan and Plx gels at 25°C and 37°C (n=6)

Formulation	Viscosity [± SD (cP)]
	25°C	37°C
Chitosan gel	1,200±0	973.666±2.081
NP-loaded chitosan gel	841.333±2.516	736.333±2.516
Chitosan gel-Tyrode solution	–	102.666±0.577
NP-loaded chitosan	–	131.333±1.527
gel-Tyrode solution
Plx gel	636±0	NA
NP-loaded Plx gel	178.666±1.527	268±2.645
Plx gel-Tyrode solution	–	27.2±0.1
NP-loaded Plx gel-Tyrode solution	–	35±0.264

Note: –, no data.

Abbreviations: NP, nanoparticle; Plx, poloxamer; NA, not applicable; SD, standard deviation.

Figure 3 Frequency-dependent changes of the viscoelastic properties of chitosan versus Plx gels at 25°C and 37°C (n=6).

Note: G′ is the storage modulus and G″ is the loss modulus.

Abbreviations: NP, nanoparticle; Plx, poloxamer.

Table 3 Mechanical properties of chitosan and Plx gels at 25°C and 37°C (n=6)

Formulation	Hardness (N) ± SD	Compressibility (N·sec) ± SD	Adhesiveness (N·sec) ± SD	Cohesiveness ± SD	Elasticity ± SD
Chitosan gel
25°C	0.044±0.002	0.132±0.007	0.121±0.028	1.008±0.024	0.896±0.112
37°C	0.018±0.002	0.075±0.011	0.119±0.039	1.016±0.005	1.041±0.037
NP-loaded chitosan gel
25°C	0.036±0.002	0.120±0.004	0.106±0.005	0.988±0.012	0.995±0.017
37°C	0.011±0	0.018±0.001	0.054±0.007	1.058±0.101	0.944±0.031
Chitosan gel-Tyrode solution
37°C	0.006±0.001	0.011±0.002	0.007±0.001	0.987±0.012	0.999±0.207
NP-loaded chitosan gel-Tyrode solution
37°C	0.008±0	0.018±0.001	0.007±0	1.000±0	0.987±0.048
Plx gel
25°C	0.018±0	0.114±0.003	0.006±0.001	1.058±0.027	0.951±0.021
37°C	0.189±0.009	0.355±0.019	0.297±0.017	1.008±0.005	0.905±0.017
NP-loaded Plx gel
25°C	0.013±0	0.064±0.004	0.005±0.001	1.032±0.056	0.966±0.014
37°C	0.111±0.009	0.193±0.044	0.104±0.008	1.096±0.224	0.997±0.089
Plx gel-Tyrode solution
37°C	0.005±0	0.006±0.001	0.004±0	1.025±0.051	0.974±0.084
NP-loaded Plx gel-Tyrode solution
37°C	0.007±0	0.028±0	0.004±0	1.033±0.027	0.982±0.079

Abbreviations: NP, nanoparticle; Plx, poloxamer; SD, standard deviation.

Table 4 Bioadhesion values and detachment forces of chitosan and Plx gels (n=6)

Formulation	Bioadhesion mN.mm ± SD	Detachment force (mN) ± SD
Chitosan gel	2,066.18±236.34	673.57±83.99
NP-loaded chitosan gel	1,795.901±42.771	1,684.092±123.612
Chitosan gel-Tyrode solution	1,406.736±39.712	512.834±60.238
NP-loaded chitosan gel-Tyrode solution	1,003.622±48.189	462.074±33.617
Plx gel	1,951.74±186.17	840.63±150.93
NP-loaded Plx gel	1,103.670±81.016	975.559±3.315
Plx gel-Tyrode solution	1,072.62±51.76	346.33±52.83
NP-loaded Plx gel-Tyrode solution	378.234±22.462	423.760±48.509

Abbreviations: NP, nanoparticle; Plx, poloxamer; SD, standard deviation.

Figure 4 In vitro release (A) and ex vivo permeation (B) profiles of Gem-HCl from NPs and NP-loaded chitosan and Plx gels (n=6).

Notes: ∆, Gem-HCl solution; ○ Chitosan–TGA NPs; ▲, NP-loaded chitosan gel; ■, NP-loaded Plx gel. The error bars at some timepoints cannot be seen because they are smaller than the markers.

Abbreviations: Gem-HCl, gemcitabine hydrochloride; NP, nanoparticle; TGA, thioglycolic acid; Plx, poloxamer; min, minutes.

Figure 5 Microscopic images of bovine bladder mucosa.

Notes: Healthy bladder mucosa (A); bladder mucosa treated with chitosan–TGA NPs (B); bladder mucosa treated with NP-loaded chitosan gel (C); bladder mucosa treated with NP-loaded Plx gel (D). ➔, urothelium, and ★, lamina propria. H&E staining; magnification ×40.

Abbreviations: TGA, thioglycolic acid; NP, nanoparticle; Gem-HCl, gemcitabine hydrochloride; Plx, poloxamer; H&E, hematoxylin eosin.