The ‘Back-to-nature’ concept has currently been adopted intensively in various industries, especially the pharmaceutical industry. In the past few decades, the overuse of synthetic chemicals has caused severe damage to the environment and ecosystem. One class of natural materials developed to substitute artificial chemicals in the pharmaceutical industries is the natural polymers, including cellulose and its derivatives. The development of nanocelluloses as nanocarriers in drug delivery systems has reached an advanced stage. Cellulose nanofiber (CNF), nanocrystal cellulose (NCC), and bacterial nanocellulose (BC) are the most common nanocellulose used as nanocarriers in drug delivery systems. Modification and functionalization using various processes and chemicals have been carried out to increase the adsorption and drug delivery performance of nanocellulose. Nanocellulose may be attached to the drug by physical interaction or chemical functionalization for covalent drug binding. Current development of nanocarrier formulations such as surfactant nanocellulose, ultra-lightweight porous materials, hydrogel, polyelectrolytes, and inorganic hybridizations has advanced to enable the construction of stimuli-responsive and specific recognition characteristics. Thus, an opportunity has emerged to develop a new generation of nanocellulose-based carriers that can modulate the drug conveyance for diverse drug characteristics. This review provides insights into selecting appropriate nanocellulose-based hybrid materials and the available modification routes to achieve satisfactory carrier performance and briefly discusses the essential criteria to achieve high-quality nanocellulose.

The utilization of natural gum polysaccharides as the vehicle for drug delivery systems and other biomedical applications has increased in recent decades. Their biocompatibility, biodegradability, and price are much cheaper than other materials. It is also renewable and available in massive amounts, which are the main reasons for its use in pharmaceutical applications. Gum can be easily functionalized with other natural polymers to enhance their applications. Various aspects of the utilization of natural gums in the forms of polyelectrolyte complexes (PECs) for drug delivery systems are discussed in this review. The application of different mathematical models were used to represent the drug release mechanisms from PECs; these models include a zero-order equation, first-order equation, Higuchi, simplified Higuchi, Korsmeyer–Peppas, and Peppas–Sahlin.

Kaffir lime peels extract was used as an agent for the reduction of graphene oxide (GO) into reduced graphene oxide (rGO) via a simple room temperature-dispersion process. The GO obtained from the Hummers process is dispersed in polyphenols rich extract at a varied GO-to-extract ratio of 1:1, 1:2, 1:3, and 1:4. The formation of rGO was confirmed through SEM, FTIR, XPS, XRD, and N₂ sorption characterization. The restoration of C=C group and the reduction of several oxygen-containing groups confirmed the successful formation of rGO from GO. The resultant rGOs were used in the adsorption system for methylene blue uptake. The results indicated that the rGOs prepared at a GO-to-extract ratio of 1:2 had the highest adsorption capacity than rGO at other ratios. The XPS spectrum analysis of rGO 1:2 showed a higher C-C/C-O ratio than the other rGOs, indicating a higher number of adsorption sites which aid in improving the adsorption performance. The adsorption isotherm and kinetic studies were conducted to gain insight into the mechanism and rate of methylene blue uptake by the rGOs. The adsorption isotherm systems were consistent with Langmuir isotherm model with the highest adsorption capacity of 118 mg g^–1 by rGO 1:2. The kinetic adsorption data are well represented by the pseudo-second order model, the adsorption equilibrium was achieved within 400 min with the overall uptake rate of 0.3 mg g^–1 min^–1.

In this study, a novel MIL-100(Fe)@TiO₂ composite was synthesized and used as the adsorbent to remove Rhodamine B from synthetic wastewater through adsorption and photocatalytic degradation. The composite was synthesized successfully using solvothermal methods. MIL-100(Fe)@TiO₂ composite has excellent adsorption and photodegradation capability for Rhodamine B removal. The reusability of the materials was observed, with the conclusion that the material still had good adsorption and photocatalytic performance after five cycles of consecutive experiments. The adsorption isotherm, kinetic, and thermodynamic studies of the removal of Rhodamine B were also conducted. The Langmuir model represented the adsorption equilibrium data better than other models. The kinetics of adsorption of Rhodamine B was presented well by pseudo-first-order. The thermodynamic study verified that the physisorption mechanism was more dominant than chemisorption. The addition of Fenton was also proven to be successful in increasing the photocatalytic abilities of the synthesized materials.