Glucose-Sensitive Nanoparticles Based On Poly(3-Acrylamidophenylboronic Acid-Block-N-Vinylcaprolactam) For Insulin Delivery

Figures & data

Scheme 1 Schematic representation of temperature- and glucose-sensitive poly (3-acrylamidophenylboronic acid-block-N-vinylcaprolactam) p(AAPBA-b-NVCL) nanoparticles.

Scheme 2 Synthesis of p(AAPBA).

Scheme 3 Synthesis of p(AAPBA-b-NVCL).

Table 1 LCST, The Molecular Weights (Mw And Mn), Molecular Weight Distributions And Size Distribution Of Self-Assembled Nanomicelles With Different Ratios

Samples	p(AAPBA)/NVCL	Mw	Mn	PDI
p(AAPBA)	100/0	5.4×10^4	4.5×10^4	1.20
p(AAPBA-b-NVCL)1	100/50	6.4×10^4	5.3×10^4	1.21
p(AAPBA-b-NVCL)2	100/100	6.7×10^4	5.5×10^4	1.22
p(AAPBA-b-NVCL)3	100/200	7.2×10^4	5.9×10^4	1.22
p(AAPBA-b-NVCL)4	100/500	7.9×10^4	6.4×10^4	1.23

Notes: Mn, Mw, and PDI were determined by gel permeation chromatography. LCST was determined by UV-vis spectroscopy.

Figure 1 FT-IR spectra of NVCL, AAPBA, pAAPBA, and p(AAPBA-b-NVCL)3.

Figure 2 ¹H-NMR spectra of (A) NVCL, (B) AAPBA, (C) pAAPBA, and (D) p(AAPBA-b-NVCL)3.

Table 2 The LCST And Zeta Potential Of p(AAPBA-b-NVCL) Nanoparticles With Different Ratios

Samples	LCST	Zeta Potential (mV)
p(AAPBA)	–	−40.6±1.2
p(AAPBA-b-NVCL)1	33.5°C	−37.5±0.5
p(AAPBA-b-NVCL)2	35.5°C	−36.0±0.7
p(AAPBA-b-NVCL)3	37.5°C	−35.2±0.7
p(AAPBA-b-NVCL)4	40.5°C	−34.5±0.5

Note: LCST was determined by UV-vis spectroscopy.

Figure 3 Hydrodynamic diameters at different: (A) pH, (B) temperatures, (C) glucose concentration, and (D) reversible glucose sensitivity.

Figure 4 TEM of p(AAPBA-b-NVCL)3 nanoparticles (A) before and (B) after treatment with 3 mg/mL glucose.

Table 3 Insulin Loading Capacity And Encapsulation Efficiency Of p(AAPBA-B-NVCL) Nanoparticles

Group	LC(%)	EF(%)
p(AAPBA)	12.4±1.0	80.9±6.8
p(AAPBA-b-NVCL)1	12.6±1.6	72.2±7.1
p(AAPBA-b-NVCL)2	12.8±1.4	71.7±6.2
p(AAPBA-b-NVCL)3	13.1±1.7	73.5±7.4
p(AAPBA-b-NVCL)4	12.5±1.2	71.6±7.3

Figure 5 In vitro cumulative release of insulin at pH 7.4 in PBS from (A) was p(AAPBA), p(AAPBA-b-NVCL)1, p(AAPBA-b-NVCL)2, p(AAPBA-b-NVCL)3, and p(AAPBA-b-NVCL)4 at 0 mg/mL glucose concentration; (B) was p(AAPBA), p(AAPBA-b-NVCL)1, p(AAPBA-b-NVCL)2, p(AAPBA-b-NVCL)3, and p(AAPBA-b-NVCL)4 at 1 mg/mL glucose concentration; (C) was p(AAPBA), p(AAPBA-b-NVCL)1, p(AAPBA-b-NVCL)2, p(AAPBA-b-NVCL)3, and p(AAPBA-b-NVCL)4 at 3 mg/mL glucose concentration; and (D) was p(AAPBA-b-NVCL)3 nanoparticles at 0, 1, and 3 mg/mL glucose concentrations.

Figure 6 Cell viability of p(AAPBA-b-NVCL) nanoparticles by MTT assay at 37°C after incubation for 24 hrs. All values are presented as mean±SD (n = 5).

Figure 7 Representative images of HE staining results from (A) heart, (B) liver, (C) spleen, (D) lung, and (E) kidney with 1) control group (0mg); 2) p(AAPBA-b-NVCL)1 group (10mg); 3) p(AAPBA-b-NVCL)2 group (10mg); 4) p(AAPBA-b-NVCL)3 group (10mg); and 5) p(AAPBA-b-NVCL)4 group (10mg).

Table 4 Effect Of Administration By Injection Of Nanoparticles On The Biochemical Parameters Of Rats After 10 d (n=5, mean±SD)

Parameter	Control Group	Observation Group (mg/kg)
p(AAPBA-b-NVCL)1	p(AAPBA-b-NVCL)2	p(AAPBA-b-NVCL)3	p(AAPBA-b-NVCL)4
Serum creatinine (mg/dL)	3.48±0.17	3.50±0.21	3.52±0.33	3.49±0.27	3.55±0.26
Serum glutathione (mg/dL)	0.65±0.08	0.62±0.07	0.64±0.11	0.62±0.08	0.64±0.13
Total cholesterol (mg/dL)	72.39±5.87	72.57±5.16	72.42±7.82	71.48±6.31	72.48±5.94
Glucose (mg/dL)	254.25±10.67	252.35±9.26	251.39±11.27	250.35±9.23	252.37±9.262
Uric acid (mg/dL)	5.18±0.45	5.23±0.29	5.18±0.56	5.22±0.48	5.51±0.49
AST (U/L)	40.15±5.21	43.14±6.31	42.26±5.81	41.57±5.05	40.95±4.92
ALT (U/L)	92.65±5.18	97.24±6.92	95.86±4.35	95.43±5.72	93.35±5.18

Figure 8 Blood glucose concentration after injection (A over 96 hrs, B over 6 hrs, because A did not show hypoglycemic effect within the first 6 hrs, and so we placed it separately, that is as B).