Correction: Characterization of chitosan- and ß-cyclodextrin-modified forms of magnesium-doped hydroxyapatites as enhanced carriers for levofloxacin: loading, release, and anti-inflammatory properties.

[This corrects the article DOI: 10.1039/D4RA02144D.].

Characterization of chitosan- and ß-cyclodextrin-modified forms of magnesium-doped hydroxyapatites as enhanced carriers for levofloxacin: loading, release, and anti-inflammatory properties.

An advanced form of magnesium-rich hydroxyapatite (Mg·HAP) was modified with two types of biopolymers, namely chitosan (CH/Mg·HAP) and ß-cyclodextrin (CD/Mg·HAP), producing two types of bio-composites. The synthesized materials were developed as enhanced carriers for levofloxacin to control its loading, release, and anti-inflammatory properties. The polymeric modification significantly improved the loading efficiency to 281.4 mg g-1 for CH/Mg·HAP and 332.4 mg g-1 for CD/Mg·HAP compared with 218.3 mg g-1 for Mg·HAP. The loading behaviors were determined using conventional kinetic and isotherm models and mathematical parameters of new equilibrium models (the monolayer model of one energy). The estimated density of effective loading sites (Nm (LVX) = 88.03 mg g-1 (Mg·HAP), 115.8 mg g-1 (CH/Mg·HAP), and 138.5 mg g-1 (CD/Mg·HAP)) illustrates the markedly higher loading performance of the modified forms of Mg·HAP. Moreover, the loading energies (<40 kJ mol-1) in conjunction with the capacity of each loading site (n > 1) and Gaussian energies (<8 kJ mol-1) signify the physical trapping of LVX molecules in vertical orientation. The addressed materials validate prolonged and continuous release behaviors. These behaviors accelerated after the modification procedures, as the complete release was identified after 160 h (CH/Mg·HAP) and 200 h (CD/Mg·HAP). The releasing behaviors are regulated by both diffusion and erosion mechanisms, according to the kinetic investigations and diffusion exponent analysis (>0.45). The entrapping of LVX into Mg·HAP induces its anti-inflammatory properties against the generation of cytokines (IL-6 and IL-8) in human bronchial epithelia cells (NL20), and this effect displays further enhancement after the integration of chitosan and ß-cyclodextrin.

Synthesis and Characterization of Mg-Hydroxyapatite and Its ß-Cyclodextrin Composite as Enhanced Bio-Carrier of 5-Fluorouracil Drug; Equilibrium and Release Kinetics.

An advanced form of magnesium-doped hydroxyapatite (Mg·HAP) was integrated in composite with ß-cyclodextrin producing a safe biocomposite (ß-CD/HAP) as an enhanced delivery structure of traditional 5-fluorouracil (5-FU) chemotherapy during the treatment stages of colorectal cancer cells. The qualifications of ß-CD/HAP as a carrier for 5-FU were followed based on the loading, release, and cytotoxicity as compared to Mg·HAP. ß-CD/HAP composite exhibits notably higher 5-FU encapsulation capacity (272.3 mg/g) than Mg·HAP phase (164.9 mg/g). The 5-FU encapsulation processes into ß-CD/HAP display the isotherm behavior of the Freundlich model (R2 = 0.99) and kinetic assumptions of pseudo-first order kinetic (R2 > 0.95). The steric studies reflect a strong increment in the quantities of the free sites after the ß-CD integration steps (Nm = 61.2 mg/g) as compared to pure Mg·HAP (Nm = 42.4 mg/g). Also, the capacity of each site was enhanced to be loaded by 5 of 5-FU molecules (n = 4.45) in a vertical orientation. The 5-FU encapsulation energy into ß-CD/HAP (<40 kJ/mol) reflects physical encapsulation reactions involving van der Waals forces and hydrogen bonding. The 5-FU release profiles of ß-CD/HAP exhibit slow and controlled properties for about 80 h either in gastric fluid (pH 1.2) or in intestinal fluid (pH 7.4). The release kinetics and diffusion exponent (>0.45) signify non-Fickian transport and complex erosion/diffusion release mechanism. The free ß-CD/HAP particles display a considerable cytotoxic effect on the HCT-116 cancer cells (33.62% cell viability) and its 5-FU-loaded product shows a strong cytotoxic effect (2.91% cell viability).

Insight into the synergetic, steric and energetic properties of zeolitization and cellulose fiber functionalization of diatomite during the adsorption of Cd(ii): advanced equilibrium studies.

The adsorption potentiality of zeolitized diatomite (ZD) frustules and their cellulose hybridized (C/ZD) product for Cd(ii) ions was assessed in synergetic studies to investigate the impact of the modification processes. The adsorption properties were illustrated based on the steric and energetic parameters of the applied advanced equilibrium modeling (monolayer model of one energy). The cellulose hybridization process increased the adsorption properties of Cd(ii) significantly to 229.4 mg g-1 as compared to ZD (180.8 mg g-1) and raw diatomite (DA) (127.8 mg g-1) during the saturation state. The steric investigation suggested a notable increase in the quantities of the active sites after the zeolitization (Nm = 62.37 mg g-1) and cellulose functionalization (Nm = 98.46 mg g-1), which illustrates enhancement in the Cd(ii) uptake capacity of C/ZD. Moreover, each active site of C/ZD can absorb about 4 ions of Cd(ii) ZD, which occur in a vertical orientation. The energetic studies, including Gaussian energy (<8 kJ mol-1) and retention energy (<8 kJ mol-1), demonstrate the physical uptake of Cd(ii), which might involve cooperating van der Waals forces (4-10 kJ mol-1), hydrophobic bonds (5 kJ mol-1), dipole forces (2-29 kJ mol-1), and hydrogen bonding (<30 kJ mol-1) in addition to zeolitic ion exchange mechanisms (0.6-25 kJ mol-1). The behaviors and values of entropy, internal energy, and free enthalpy as the assessed thermodynamic functions validate the exothermic and spontaneous properties of the Cd(ii) retention by ZD and the C/ZD composite.

Characterization of cellulose-functionalized phillipsite biocomposite as an enhanced carrier of oxaliplatin drug during the treatment of colorectal cancer: loading, release, and cytotoxicity.

Natural phillipsite (N.Ph) was hybridized with cellulose fibers to produce a safe biocomposite (CF/N.Ph) as an enhanced delivery structure of traditional oxaliplatin (OXPN) chemotherapy during the treatment stages of colorectal cancer cells. The requirements of CF/N.Ph as a carrier for OXPN were followed based on the loading, release, and cytotoxicity compared to N.Ph. CF/N.Ph composite exhibits a notably higher OXPN encapsulation capacity (311.03 mg g-1) than the N.Ph phase (79.6 mg g-1). The OXPN encapsulation processes into CF/N.Ph display the isotherm behavior of the Freundlich model (R2 = 0.99) and the kinetic assumptions of pseudo-first order kinetic (R2 > 0.95). The steric studies reflect a strong increment in the quantities of the free sites after the cellulose hybridization steps (Nm = 100.01 mg g-1) compared to pure N.Ph (Nm = 27.94 mg g-1). Additionally, the capacity of each site was enhanced to be loaded by 4 OXPN molecules (n = 3.11) compared to 3 by N.Ph (n = 2.85) in a vertical orientation. The OXPN encapsulation energy into CF/N.Ph (<40 kJ mol-1) reflects physical encapsulation reactions involving electrostatic attraction, van der Waals forces, and hydrogen bonding. The OXPN release profiles of CF/N.Ph exhibit slow and controlled properties for about 150 h either at pH 5.5 or at pH 7.4. The release kinetics and diffusion exponent (>0.45) signify non-Fickian transport and a complex erosion/diffusion release mechanism. The free CF/N.Ph particles display a considerable cytotoxic effect on HCT-116 cancer cells (46.91% cell viability), and its OXPN-loaded product shows a strong cytotoxic effect (3.14% cell viability).

Synthesis and characterization of cellulose functionalized zeolitic diatomite as an enhanced carrier of oxaliplatin drug; loading, release, and cytotoxicity.

Natural diatomite frustules (D) were incorporated in zeolitization and cellulose functionalization processes to obtain zeolitized diatomite (ZD) and cellulose fibrous/zeolitized diatomite composite (CF/ZD). The modified products were assessed as potential carriers of oxaliplatin drug (OXPL) with enhanced properties. The prepared ZD (112.5 mg/g) and CF/ZD (268.3 mg/g) structures exhibit significantly enhanced encapsulation capacities as compared to raw diatomite (65.9 mg/g). The occurred encapsulation reactions follow the classic Pseudo-first order kinetic (R2 > 0.93) and traditional Langmuir isotherm (R2 = 0.99). The estimated effective encapsulation site density of CF/ZD is 104.8 mg/g which is a notably higher value than ZD (44.6 mg/g) and D (28.4 mg/g). Moreover, each effective site can be occupied with up to 3 molecules of OXPL molecules in vertical forms involving multi-molecular mechanisms. The encapsulation energy (<40 KJ/mol) suggested the predominant effects of the physical mechanisms during the encapsulation reactions. The release profiles of ZD as well as CF/ZD exhibit slow and controlled properties for about 100 h either at pH 5.5 or at pH 7.4. The release kinetic studies involving the obtained diffusion exponent values (>0.45) suggested non-Fickian transport and complex erosion/diffusion release mechanism. These structures exhibit enhanced cytotoxic effects on the HCT-116 cancer cell lines (D (18.78 % cell viability), ZD (9.76 % cell viability), and CF/ZD (3.16 % cell viability).