The effect of methacrylation on the behavior of Gum Arabic as pH-responsive matrix for colon-specific drug delivery

Pectin Hydrogels Ph Stability as Affected by Methacrylic Grafting to Low Methoxy Pectin Structure

“…Conversely, only, 5.05±0.29% of BSA loaded MP gels was released after 7 h of exposure at acidic medium; the greatest amount (94.41±0.63%) of BSA released was recorded for 1.5 h of exposure to neutral pH medium. These results are comparable to Gerola et al (2016), who developed hydrogels by modified Gum Arabic with glycidyl methacrylate that are more sensitive to neutral pH inducing the maximum amount of the compound released, contrary to the previous reports by Santacruz-Vázquez et al (2013), who found that nano-capsules by Arabic Gum without modification promote a faster and higher compound release at acidic pH than neutral pH, such occurs with P gel without modification. Protein released decreased over time (Fig.…”

“…At pH values below the pKa, the carboxylic groups are unionized, which reduces the attraction among pectin with water molecules and calcium ions, and diminishes electrostatic repulsion between pectin molecules, all which triggers hysteresis and pectin aggregation (Sriamornsak, 2003). In contrast, at neutral pH exposure, the pectin chains turn negatively charged, which causes a strong repulsion between the chains of pectin and the stability of the hydrogel structure is lost (Fares et al, 2010;Gerola et al, 2016).…”

“…Eventually, a three-stage release matrix could be developed for biomedical applications. The methacrylation of polysaccharides is an effective method to make hydrogels with an effective prevention of erosion/degradation (Gerola et al, 2016). In addition, the pectin has shown resistance to proteases and amylases from the upper gastrointestinal tract, while selective digestion by the microbiota present in the colon (Wong et al, 2011).…”

Uncommon Sorption Mechanism of Aromatic Compounds onto Poly(Vinyl Alcohol)/Chitosan/Maleic Anhydride-β-Cyclodextrin Hydrogels

“…Firstly, oscillatory measurements were carried out at 25 °C; the frequency sweep (τ = 1 Pa) showed a typical viscoelastic behavior at the whole range of applied frequency. It was verified that the gels exhibited a typical solid-like rheological behavior, being the values of the storage modulus G' higher than the loss modulus G´´ [63,64], as expected. Amplitude sweep measurements (f = 1 Hz) followed a similar trend, with a weak dependence of the G´ and G´´ in most of the applied stress range.…”

“…This suggests that the adsorption capacity can be affected by the interaction degree between adsorbate-adsorbent and mainly by adsorbate-absorbate interactions [53]. The PHAs show smaller interaction with the hydrogel than the BTXs [63]. Besides, the interaction between aromatics is likely more significant than the adsorbate-adsorbent one [65].…”