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Fluorescence tomographic imaging of sentinel lymph node using near-infrared emitting bioreducible dextran nanogels.

Li J, Jiang B, Lin C, Zhuang Z - Int J Nanomedicine (2014)

Bottom Line: However, SLN mapping agents used in the clinic frequently cause side effects and complications in the patients.Fluorescence imaging analysis showed that Dex-Cy7 nanogels had an enhanced photostability when compared to Cy7 alone.The results of this study suggest that NIR-emitting polymeric nanogels based on bioreducible dextran-deoxycholic acid conjugates show high potential as fluorescence nanoprobes for safe and noninvasive SLN mapping.

View Article: PubMed Central - PubMed

Affiliation: Department of Breast Surgery, Shanghai First Maternity and Infant hospital, Tongji University, Shanghai, People's Republic of China.

ABSTRACT
Sentinel lymph node (SLN) mapping is a critical procedure for SLN biopsy and its diagnosis as tumor metastasis in clinical practice. However, SLN mapping agents used in the clinic frequently cause side effects and complications in the patients. Here, we report the development of a near-infrared (NIR) emitting polymeric nanogel with hydrodynamic diameter of ~28 nm - which is the optimal size for SLN uptake - for noninvasive fluorescence mapping of SLN in a mouse. This polymeric nanogel was obtained by coupling Cy7, an NIR dye, to the self-assembled nanogel from disulfide-linked dextran-deoxycholic acid conjugate with the dextran of 10 kDa, denoted as Dex-Cy7. Fluorescence imaging analysis showed that Dex-Cy7 nanogels had an enhanced photostability when compared to Cy7 alone. After intradermal injection of Dex-Cy7 nanogel into the front paw of a mouse, the nanogels were able to migrate into the mouse's axillary lymph node, exhibiting longer retention time and higher fluorescence intensity in the node when compared to Cy7 alone. An immunohistofluorescence assay revealed that the nanogels were localized in the central region of lymph node and that the uptake was largely by the macrophages. In vitro and in vivo toxicity results indicated that the dextran-based nanogels were of low cytotoxicity at a polymer concentration up to 1,000 μg/mL and harmless to normal liver and kidney organs in mice at an intravenous dose of 1.25 mg/kg. The results of this study suggest that NIR-emitting polymeric nanogels based on bioreducible dextran-deoxycholic acid conjugates show high potential as fluorescence nanoprobes for safe and noninvasive SLN mapping.

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1H NMR spectrum of (A) Dex–SS–NH2 and (B) Dex10k–SS–DCA.Abbreviations: Dex–SS–NH2, dextran-cysteamine conjugate; Dex–SS–DCA, disulfide-linked dextran-deoxycholic acid conjugate; DMSO, dimethyl sulfoxide; ppm, parts per million; D2O, deuterium oxide.
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f2-ijn-9-5667: 1H NMR spectrum of (A) Dex–SS–NH2 and (B) Dex10k–SS–DCA.Abbreviations: Dex–SS–NH2, dextran-cysteamine conjugate; Dex–SS–DCA, disulfide-linked dextran-deoxycholic acid conjugate; DMSO, dimethyl sulfoxide; ppm, parts per million; D2O, deuterium oxide.

Mentions: Dex–SS–DCA conjugates were prepared via a four-step synthesis (Figure 1). First, thiolated dextran (Dex–SH) with the substitution degree (DS, defined as the number of thiol groups per 100 anhydroglucose rings of dextran) of five was synthesized via a two-step procedure according to our previous report.16 Next, Dex–SH was reacted with PDA to give dextran-cysteamine conjugate (Dex–SS–NH2). Finally, Dex10k–SS–NH2 was coupled with DCA via an EDC/NHS activation reaction to yield Dex–SS–DCA. As a typical example for the synthesis of Dex10k–SS–NH2, Dex10k–SH (DS 5, 0.0125 mmol SH) was reacted overnight with PDA (0.25 mmol) in acidic water (pH5, 5 mL) under nitrogen protection at room temperature. The solution was diluted with acidic water (pH~5) and purified by ultrafiltration (molecular weigh cut-off 1,000), and the dextran-cysteamine conjugate (Dex10k–SS–NH2) was obtained as a white powder after freeze-drying (yield: 90%). For the synthesis of Dex10k–SS–DCA, DCA (0.25 mmol) was activated by EDC/NHS in dimethyl sulfoxide (DMSO, 1 mL) for 1 hour. The DCA solution was reacted with Dex10k–SS–NH2 (0.125 mmol NH2) and pyridine (0.25 mmol) in deionized water (0.2 mL) for 2 days under nitrogen protection at room temperature. The residue mixture was purified by dialysis in ethanol (3×500 mL), and the precipitate was dissolved in DMSO (2 mL) for exhaustive dialysis in deionized water (3×5 L). Finally, Dex10k–SS–DCA was obtained as a white solid powder after freeze-drying. 1H NMR of Dex10k–SS–NH2 (D2O, δ): 2.8–3.0 (4H, CH2SSCH2), 3.37 (4H, CH2CH2SS-CH2CH2NH2), 5.0 (s, 1H, dextran anomeric proton). 1H NMR of Dex10k–SS–DCA (D2O, δ): 0.58 (3H, 8–CH3), 0.84(1H, 7–CH3), 0.90 (1H, 6–CH3), 5.0 (s, 1H, dextran anomeric proton), as shown in Figure 2.


Fluorescence tomographic imaging of sentinel lymph node using near-infrared emitting bioreducible dextran nanogels.

Li J, Jiang B, Lin C, Zhuang Z - Int J Nanomedicine (2014)

1H NMR spectrum of (A) Dex–SS–NH2 and (B) Dex10k–SS–DCA.Abbreviations: Dex–SS–NH2, dextran-cysteamine conjugate; Dex–SS–DCA, disulfide-linked dextran-deoxycholic acid conjugate; DMSO, dimethyl sulfoxide; ppm, parts per million; D2O, deuterium oxide.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4260688&req=5

f2-ijn-9-5667: 1H NMR spectrum of (A) Dex–SS–NH2 and (B) Dex10k–SS–DCA.Abbreviations: Dex–SS–NH2, dextran-cysteamine conjugate; Dex–SS–DCA, disulfide-linked dextran-deoxycholic acid conjugate; DMSO, dimethyl sulfoxide; ppm, parts per million; D2O, deuterium oxide.
Mentions: Dex–SS–DCA conjugates were prepared via a four-step synthesis (Figure 1). First, thiolated dextran (Dex–SH) with the substitution degree (DS, defined as the number of thiol groups per 100 anhydroglucose rings of dextran) of five was synthesized via a two-step procedure according to our previous report.16 Next, Dex–SH was reacted with PDA to give dextran-cysteamine conjugate (Dex–SS–NH2). Finally, Dex10k–SS–NH2 was coupled with DCA via an EDC/NHS activation reaction to yield Dex–SS–DCA. As a typical example for the synthesis of Dex10k–SS–NH2, Dex10k–SH (DS 5, 0.0125 mmol SH) was reacted overnight with PDA (0.25 mmol) in acidic water (pH5, 5 mL) under nitrogen protection at room temperature. The solution was diluted with acidic water (pH~5) and purified by ultrafiltration (molecular weigh cut-off 1,000), and the dextran-cysteamine conjugate (Dex10k–SS–NH2) was obtained as a white powder after freeze-drying (yield: 90%). For the synthesis of Dex10k–SS–DCA, DCA (0.25 mmol) was activated by EDC/NHS in dimethyl sulfoxide (DMSO, 1 mL) for 1 hour. The DCA solution was reacted with Dex10k–SS–NH2 (0.125 mmol NH2) and pyridine (0.25 mmol) in deionized water (0.2 mL) for 2 days under nitrogen protection at room temperature. The residue mixture was purified by dialysis in ethanol (3×500 mL), and the precipitate was dissolved in DMSO (2 mL) for exhaustive dialysis in deionized water (3×5 L). Finally, Dex10k–SS–DCA was obtained as a white solid powder after freeze-drying. 1H NMR of Dex10k–SS–NH2 (D2O, δ): 2.8–3.0 (4H, CH2SSCH2), 3.37 (4H, CH2CH2SS-CH2CH2NH2), 5.0 (s, 1H, dextran anomeric proton). 1H NMR of Dex10k–SS–DCA (D2O, δ): 0.58 (3H, 8–CH3), 0.84(1H, 7–CH3), 0.90 (1H, 6–CH3), 5.0 (s, 1H, dextran anomeric proton), as shown in Figure 2.

Bottom Line: However, SLN mapping agents used in the clinic frequently cause side effects and complications in the patients.Fluorescence imaging analysis showed that Dex-Cy7 nanogels had an enhanced photostability when compared to Cy7 alone.The results of this study suggest that NIR-emitting polymeric nanogels based on bioreducible dextran-deoxycholic acid conjugates show high potential as fluorescence nanoprobes for safe and noninvasive SLN mapping.

View Article: PubMed Central - PubMed

Affiliation: Department of Breast Surgery, Shanghai First Maternity and Infant hospital, Tongji University, Shanghai, People's Republic of China.

ABSTRACT
Sentinel lymph node (SLN) mapping is a critical procedure for SLN biopsy and its diagnosis as tumor metastasis in clinical practice. However, SLN mapping agents used in the clinic frequently cause side effects and complications in the patients. Here, we report the development of a near-infrared (NIR) emitting polymeric nanogel with hydrodynamic diameter of ~28 nm - which is the optimal size for SLN uptake - for noninvasive fluorescence mapping of SLN in a mouse. This polymeric nanogel was obtained by coupling Cy7, an NIR dye, to the self-assembled nanogel from disulfide-linked dextran-deoxycholic acid conjugate with the dextran of 10 kDa, denoted as Dex-Cy7. Fluorescence imaging analysis showed that Dex-Cy7 nanogels had an enhanced photostability when compared to Cy7 alone. After intradermal injection of Dex-Cy7 nanogel into the front paw of a mouse, the nanogels were able to migrate into the mouse's axillary lymph node, exhibiting longer retention time and higher fluorescence intensity in the node when compared to Cy7 alone. An immunohistofluorescence assay revealed that the nanogels were localized in the central region of lymph node and that the uptake was largely by the macrophages. In vitro and in vivo toxicity results indicated that the dextran-based nanogels were of low cytotoxicity at a polymer concentration up to 1,000 μg/mL and harmless to normal liver and kidney organs in mice at an intravenous dose of 1.25 mg/kg. The results of this study suggest that NIR-emitting polymeric nanogels based on bioreducible dextran-deoxycholic acid conjugates show high potential as fluorescence nanoprobes for safe and noninvasive SLN mapping.

Show MeSH
Related in: MedlinePlus