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Synthesis of double-clickable functionalised graphene oxide for biological applications.

Mei KC, Rubio N, Costa PM, Kafa H, Abbate V, Festy F, Bansal SS, Hider RC, Al-Jamal KT - Chem. Commun. (Camb.) (2015)

Bottom Line: Fourteen-percentage increase in azide content was found, after pre-treatment of GO with meta-chloroperoxybenzoic acid (mCPBA), determined with elemental analysis.No effect on A549 cell viability was found, up to 100 μg mL(-1) and 72 h of incubation, determined with the modified lactate dehydrogenase (mLDH) assay.The final conjugate was characterised with ATR-FTIR and TGA.

View Article: PubMed Central - PubMed

Affiliation: Institute of Pharmaceutical Science, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, UK. khuloud.al-jamal@kcl.ac.uk.

ABSTRACT
Azide- and alkyne-double functionalised graphene oxide (Click(2) GO) was synthesised and characterised with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA) and Raman spectroscopy. Fourteen-percentage increase in azide content was found, after pre-treatment of GO with meta-chloroperoxybenzoic acid (mCPBA), determined with elemental analysis. No effect on A549 cell viability was found, up to 100 μg mL(-1) and 72 h of incubation, determined with the modified lactate dehydrogenase (mLDH) assay. Two sequential copper(i) catalysed azide-alkyne cycloaddition (CuAAC) reactions were performed to conjugate the propargyl-modified blood-brain barrier targeting peptide Angiopep-2, and a bis-azide polyethylene glycol (MW = 3500), to the Click(2) GO. The final conjugate was characterised with ATR-FTIR and TGA.

No MeSH data available.


Thermogravimetric analysis. (A) GO and (B) GO-N3 exhibit four linear decomposition ranges when heated from 100–978 °C. A steeper curve was found in linear range Ib than Ia. (C) Click2 GO. Only two linear thermal-decomposition ranges were found throughout the heating range. It was noticed that the introduction of alkyne groups eliminated stage IV decomposition event observed in IVa and IVb.
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fig2: Thermogravimetric analysis. (A) GO and (B) GO-N3 exhibit four linear decomposition ranges when heated from 100–978 °C. A steeper curve was found in linear range Ib than Ia. (C) Click2 GO. Only two linear thermal-decomposition ranges were found throughout the heating range. It was noticed that the introduction of alkyne groups eliminated stage IV decomposition event observed in IVa and IVb.

Mentions: After confirming the introduction of azide groups on GO, Click2 GO was prepared via Steglich esterification as described in ESI,† Methods and Scheme 1. Samples were prepared with or without mCPBA, to mimic GO-N3 preparation condition. The IR spectra of Click2 GO are shown in Fig. 1B. The azide peak at 2117 or 2120 cm–1 was found in Click2 GO (–mCPBA) or Click2 GO (+mCPBA), respectively. Similar to GO-N3, the epoxidation treatment slightly increased the wavenumber of azide peak. The alkyne signal of Click2 GO could not be picked up by Raman spectroscopy (Fig. S7, ESI†). This was expected as the –C 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 C– stretching vibration on macromolecules generally has a weak IR transmittance. Furthermore, the peak location overlaps with the azide groups. The Raman spectra ID/IG (peak height) ratio was 1.32 ± 0.03 and 1.28 ± 0.01 (n = 3) for Click2 GO, without and with mCPBA, respectively. TGA was used to characterise GO, GO-N3, and Click2 GO. As shown in Fig. 2, GO exhibited 4 stages of thermal-decomposition, represented by the 4 disconnected linear weight-loss intervals with curvy turning points. GO-N3 also showed 4 linear weight-loss intervals with relatively sharp turning points. A higher and a sharper weight-loss slope was found in the linear range Ib than in Ia. These changes could be due to the decomposition of azide groups when the temperature approaches 200 °C, as previously reported in the literature.43 Click2 GO also showed a deep and steep drop in weight within the linear range Ic, however; only two linear ranges were found in Click2 GO; the stage 4 decomposition observed in GO (IVa) and GO-N3 (IVb) could not be seen in Click2 GO. The introduction of TMS-protected propargyl alcohol on the carboxylic groups seems to have stabilised the GO at 800 °C or higher. Detailed information on slopes analysis is summarised in Tables S4–S6 (ESI†).


Synthesis of double-clickable functionalised graphene oxide for biological applications.

Mei KC, Rubio N, Costa PM, Kafa H, Abbate V, Festy F, Bansal SS, Hider RC, Al-Jamal KT - Chem. Commun. (Camb.) (2015)

Thermogravimetric analysis. (A) GO and (B) GO-N3 exhibit four linear decomposition ranges when heated from 100–978 °C. A steeper curve was found in linear range Ib than Ia. (C) Click2 GO. Only two linear thermal-decomposition ranges were found throughout the heating range. It was noticed that the introduction of alkyne groups eliminated stage IV decomposition event observed in IVa and IVb.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4594119&req=5

fig2: Thermogravimetric analysis. (A) GO and (B) GO-N3 exhibit four linear decomposition ranges when heated from 100–978 °C. A steeper curve was found in linear range Ib than Ia. (C) Click2 GO. Only two linear thermal-decomposition ranges were found throughout the heating range. It was noticed that the introduction of alkyne groups eliminated stage IV decomposition event observed in IVa and IVb.
Mentions: After confirming the introduction of azide groups on GO, Click2 GO was prepared via Steglich esterification as described in ESI,† Methods and Scheme 1. Samples were prepared with or without mCPBA, to mimic GO-N3 preparation condition. The IR spectra of Click2 GO are shown in Fig. 1B. The azide peak at 2117 or 2120 cm–1 was found in Click2 GO (–mCPBA) or Click2 GO (+mCPBA), respectively. Similar to GO-N3, the epoxidation treatment slightly increased the wavenumber of azide peak. The alkyne signal of Click2 GO could not be picked up by Raman spectroscopy (Fig. S7, ESI†). This was expected as the –C 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 C– stretching vibration on macromolecules generally has a weak IR transmittance. Furthermore, the peak location overlaps with the azide groups. The Raman spectra ID/IG (peak height) ratio was 1.32 ± 0.03 and 1.28 ± 0.01 (n = 3) for Click2 GO, without and with mCPBA, respectively. TGA was used to characterise GO, GO-N3, and Click2 GO. As shown in Fig. 2, GO exhibited 4 stages of thermal-decomposition, represented by the 4 disconnected linear weight-loss intervals with curvy turning points. GO-N3 also showed 4 linear weight-loss intervals with relatively sharp turning points. A higher and a sharper weight-loss slope was found in the linear range Ib than in Ia. These changes could be due to the decomposition of azide groups when the temperature approaches 200 °C, as previously reported in the literature.43 Click2 GO also showed a deep and steep drop in weight within the linear range Ic, however; only two linear ranges were found in Click2 GO; the stage 4 decomposition observed in GO (IVa) and GO-N3 (IVb) could not be seen in Click2 GO. The introduction of TMS-protected propargyl alcohol on the carboxylic groups seems to have stabilised the GO at 800 °C or higher. Detailed information on slopes analysis is summarised in Tables S4–S6 (ESI†).

Bottom Line: Fourteen-percentage increase in azide content was found, after pre-treatment of GO with meta-chloroperoxybenzoic acid (mCPBA), determined with elemental analysis.No effect on A549 cell viability was found, up to 100 μg mL(-1) and 72 h of incubation, determined with the modified lactate dehydrogenase (mLDH) assay.The final conjugate was characterised with ATR-FTIR and TGA.

View Article: PubMed Central - PubMed

Affiliation: Institute of Pharmaceutical Science, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, UK. khuloud.al-jamal@kcl.ac.uk.

ABSTRACT
Azide- and alkyne-double functionalised graphene oxide (Click(2) GO) was synthesised and characterised with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA) and Raman spectroscopy. Fourteen-percentage increase in azide content was found, after pre-treatment of GO with meta-chloroperoxybenzoic acid (mCPBA), determined with elemental analysis. No effect on A549 cell viability was found, up to 100 μg mL(-1) and 72 h of incubation, determined with the modified lactate dehydrogenase (mLDH) assay. Two sequential copper(i) catalysed azide-alkyne cycloaddition (CuAAC) reactions were performed to conjugate the propargyl-modified blood-brain barrier targeting peptide Angiopep-2, and a bis-azide polyethylene glycol (MW = 3500), to the Click(2) GO. The final conjugate was characterised with ATR-FTIR and TGA.

No MeSH data available.