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Application of Bioresponsive Polymers in Gene Delivery
Published in Deepa H. Patel, Bioresponsive Polymers, 2020
Tamgue Serges William, Drashti Pathak, Deepa H. Patel
MAA based polycation is obtained by a reaction between primary amine and maleic anhydride which leads to the formation of a polyanion. This latter will show a relative stability at neutral pH 7.4 but will be hydrolyzed as soon as it will be in contact with acidic pH. This will lead to the degradation of MAA and exposure of primary amines, thereby regenerating the parent polycation. Some studies reported that, in general the hydrolysis kinetics of MAA derivatives is related to the nature of the substituted groups at the double bonds of MAA moiety [21, 22]. Rozema and collaborators [22] have reported a faster hydrolysis from a MAA from dimethyl maleic acid derivatives that showed a degradation half-life of 1.5 min, compared to a MAA from monomethyl maleic acid derivatives (citraconic acid amide) which showed degradation half time of 300 min.
Risedronate-loaded aerogel scaffolds for bone regeneration
Published in Drug Delivery, 2023
Nahla El-Wakil, Rabab Kamel, Azza A. Mahmoud, Alain Dufresne, Ragab E. Abouzeid, Mahmoud T. Abo El-Fadl, Amr Maged
Figure 4 shows the thermal analysis of risedronate, NFC, chitosan, citric acid, and SC-T3 aerogel scaffold. The DSC thermogram of risedronate revealed many endothermic peaks at 123.99 °C, 148.22 °C, 188.56 °C, and 198.53 °C. These peaks represent the gradual dehydration, as risedronate is a water-soluble drug containing a large amount of water known as hemipentahydrate (Redman-Furey et al., 2005). The thermal analysis of NFC showed a characteristic peak at 78.50 °C, which indicates the evaporation of water. Chitosan showed a broad peak at 105.27 °C, as a result of dehydration due to the weak hydrogen bonds between water and chitosan molecules (Zawadzki & Kaczmarek, 2010; Maged et al., 2019). The thermogram of citric acid demonstrated three endothermic peaks at 62.47 °C, 141.51 °C, and 170.16 °C. The peak below 100 °C indicates the water loss during the dehydration process; the second one represents the melting of citric acid, and is followed by decomposition occuring at the highest temperature into aconitic acid and citraconic acid anhydride (Sadik et al., 2018). The DSC analysis of the SC-T3 aerogel scaffold showed the formation of a new endothermic peak at 201.97 °C and the absence of the characteristic peaks of the individual components. This result confirms the generation of a new biopolymeric structure due to the cross-linking between chitosan and NFC.