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![NMR comparison of the (a) macroinitiator HO-G3Boc, (b) LDBC precursor 70-DL-G3-Boc and (c) amphiphilic LDBC 70-DL-G3 as a reverse micelle. Peaks from 2.19 ppm to 3.69 ppm refer to the protons signals for PAMAM-G3-Boc (Supporting Information Fig. S7, SI sample 8). The resonance peaks corresponding to the primary and tertiary hydrogens on the liner polylactide chain appear at 1.57 and 5.15 ppm (Supporting Information Fig. S9, SI LDBC samples 9 and 10). [Color figure can be viewed at wileyonlinelibrary.com]](profile/Indika-Chandrasiri-2/publication/333228067/figure/fig1/AS:773018888450049@1561313473937/NMR-comparison-of-the-a-macroinitiator-HO-G3Boc-b-LDBC-precursor-70-DL-G3-Boc-and.png)
NMR comparison of the (a) macroinitiator HO-G3Boc, (b) LDBC precursor 70-DL-G3-Boc and (c) amphiphilic LDBC 70-DL-G3 as a reverse micelle. Peaks from 2.19 ppm to 3.69 ppm refer to the protons signals for PAMAM-G3-Boc (Supporting Information Fig. S7, SI sample 8). The resonance peaks corresponding to the primary and tertiary hydrogens on the liner polylactide chain appear at 1.57 and 5.15 ppm (Supporting Information Fig. S9, SI LDBC samples 9 and 10). [Color figure can be viewed at wileyonlinelibrary.com]
Source publication
Herein, we present a facile and comprehensive synthetic methodology for the preparation of polyester‐polyamidoamine (PAMAM) (i.e., polyester: polylactide [PLA] (hydrophobic) and polyamidoamine, PAMAM [hydrophilic]) polymers. A library of PLA‐PAMAM linear dendritic block copolymers (LDBCs) in which both l and d, l polylactide were employed in mass r...
Contexts in source publication
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... shown in Figure 2, an overlay of NMR spectra shows characteristic peaks of PAMAM (2.19-3.69 ppm) and PLA (1.57, 5.15 ppm). ...
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... segments are present in the spectrum of the coupled product for precursor 70-DL-G3-Boc where 70 denotes the percentage of DL-lactide composing the LDBCs [ Fig. 2(b)]. Boc-protected LDBCs show high solubility in common solvents such as chloroform and THF; however, upon deprotection of the PAMAM block with TFA to yield 70-DL-G3, solubility dramatically decreased due to the formation of NH 3 + terminal groups (Scheme 1). NMR spectra of deprotected 70-DL-G3 ( Fig. 2c; chloroform-d) give indirect ...
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... of DL-lactide composing the LDBCs [ Fig. 2(b)]. Boc-protected LDBCs show high solubility in common solvents such as chloroform and THF; however, upon deprotection of the PAMAM block with TFA to yield 70-DL-G3, solubility dramatically decreased due to the formation of NH 3 + terminal groups (Scheme 1). NMR spectra of deprotected 70-DL-G3 ( Fig. 2c; chloroform-d) give indirect evidence of solvent-driven aggregation by the disappearance of resonance peaks for PAMAM, whereas PLA peaks remain visible. No precipitation is observed in the chloroform-d solution, which suggests the formation of a reverse-micelle where PAMAM is shielded from the solvent (i.e., micelle core) and PDLLA acts as a ...
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... understand the morphology of the self-assembled nanoparticles, TEM analysis was conducted. Additionally, the TEM observations are further confirmed by SAXS analysis (vide infra). TEM captured aggregate morphologies of sizes (radii) ranging from 4.8 to 10.4 nm (Fig. 4 and enlarged images S25-30). Uranyl formate was used as a stain to increase the contrast between the hydrophilic and hydrophobic portions. LDBC 70-L-G3 shows a distribution of bilayered vesicles and elongated worm-like particles [ Fig. 4(a)]. 50-L-G3 produces bilayered vesicles with radii ranging from 4.8 to 6.1 nm [ Fig. 4(b)]. 30-L-G3 yields core-shell micelles ...
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... Such values of AE20 to 30 mV are viewed as highly stable and are common in drug delivery literature 48 as general guidelines classifying nanoparticle dispersions employ zeta potential data to correlate colloidal stability. The critical aggregate concentrations (CAC) for the LDBCs ranged from 0.91 to 9.75 mg/L (Supporting Informa- tion Table S6, Figs. S32-334) providing further evidence of stable nanoparticles. 49 The values are comparable to those found in the literature and correlate to the candidacy of the copolymers as potential biomaterials. Specifically with the dependence of CAC on the length and weight ratio of PLA where an increase in hydrophobicity is shown to lead to a ...
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... shown in Figure 2, an overlay of NMR spectra shows characteristic peaks of PAMAM (2.19-3.69 ppm) and PLA (1.57, 5.15 ppm). ...
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... segments are present in the spectrum of the coupled product for precursor 70-DL-G3-Boc where 70 denotes the percentage of DL-lactide composing the LDBCs [ Fig. 2(b)]. Boc-protected LDBCs show high solubility in common solvents such as chloroform and THF; however, upon deprotection of the PAMAM block with TFA to yield 70-DL-G3, solubility dramatically decreased due to the formation of NH 3 + terminal groups (Scheme 1). NMR spectra of deprotected 70-DL-G3 ( Fig. 2c; chloroform-d) give indirect ...
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... of DL-lactide composing the LDBCs [ Fig. 2(b)]. Boc-protected LDBCs show high solubility in common solvents such as chloroform and THF; however, upon deprotection of the PAMAM block with TFA to yield 70-DL-G3, solubility dramatically decreased due to the formation of NH 3 + terminal groups (Scheme 1). NMR spectra of deprotected 70-DL-G3 ( Fig. 2c; chloroform-d) give indirect evidence of solvent-driven aggregation by the disappearance of resonance peaks for PAMAM, whereas PLA peaks remain visible. No precipitation is observed in the chloroform-d solution, which suggests the formation of a reverse-micelle where PAMAM is shielded from the solvent (i.e., micelle core) and PDLLA acts as a ...
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... understand the morphology of the self-assembled nanoparticles, TEM analysis was conducted. Additionally, the TEM observations are further confirmed by SAXS analysis (vide infra). TEM captured aggregate morphologies of sizes (radii) ranging from 4.8 to 10.4 nm (Fig. 4 and enlarged images S25-30). Uranyl formate was used as a stain to increase the contrast between the hydrophilic and hydrophobic portions. LDBC 70-L-G3 shows a distribution of bilayered vesicles and elongated worm-like particles [ Fig. 4(a)]. 50-L-G3 produces bilayered vesicles with radii ranging from 4.8 to 6.1 nm [ Fig. 4(b)]. 30-L-G3 yields core-shell micelles ...
Context 10
... Such values of AE20 to 30 mV are viewed as highly stable and are common in drug delivery literature 48 as general guidelines classifying nanoparticle dispersions employ zeta potential data to correlate colloidal stability. The critical aggregate concentrations (CAC) for the LDBCs ranged from 0.91 to 9.75 mg/L (Supporting Informa- tion Table S6, Figs. S32-334) providing further evidence of stable nanoparticles. 49 The values are comparable to those found in the literature and correlate to the candidacy of the copolymers as potential biomaterials. Specifically with the dependence of CAC on the length and weight ratio of PLA where an increase in hydrophobicity is shown to lead to a ...
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Citations
... Recently, we reported an accessible and robust synthetic methodology for the preparation of a library of LDBCs. 15 Bilayer vesicles were observed for the systems consisting of hydrophobic portions >50 wt % (CAC <6.59 mg/L) and attracted particular interest due to their biomimetic nature (i.e., resembling biological vesicles). This work has laid the foundation for a diverse library of biocompatible and biodegradable materials, which provides evidence of potential applications in nanomedicine. ...
... PAMAM-G3-Boc and C3 were prepared as previously reported. 15,29 All of the synthetic procedures were conducted under an ultrapurified nitrogen atmosphere using standard organic synthesis techniques (e.g., Schlenk line) unless otherwise specified. Chloroform (99.9%, ...
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... All values are, as expected, positive and large, in the same range as those reported for other positively charged polymeric nanoparticles. 42,43,54,55 The micelles exhibit the highest ζ values, which are not significantly affected by the molar mass of the hydrophobic PS block, but note that these micelles are differently aggregated (cf. Figures 3 and S16). ...
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Abstract
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