Fabrication, characterization, and potential applications of re-assembled casein micelles

Re-assembled casein micelles (rCMs), were formulated in the 1970s as a model system to understand native casein micelles (nCMs) in milk. These early works allowed an understanding of the critical factors involved in the formation of rCMs, such as minerals (citrate, phosphate, and calcium), casein type (α_s-, β-, and κ-casein) and the extent of their phosphorylation. rCMs were also used to understand the effect of treatments such as ethanol, high hydrostatic pressure and heating on the stability and integrity of the micelles. More recently, the applications of rCMs have been investigated, these include their use as a nanocarrier of bioactive molecules and as electrode-bound substrates to monitor chymosin activity by electrochemistry, to cite a few. Moreover, the potential to use rCMs in both food and non-food applications remains to be fully exploited. The advantage of choosing rCMs over nCMs as an encapsulant and a lucrative food ingredient is due to their more efficient preparation and being free from impurities. In this review, we report on the formulation of rCMs, their physico-chemical properties and their behavior under different physico-chemical treatments, along with the applications and challenges of rCMs in food systems and their industrial production as a dairy ingredient.

Coupled catalytic dephosphorylation and complex phosphate ion-exchange in networked hierarchical lanthanum carbonate grafted asymmetric bio-composite membrane

The remediation of non-reactive phosphate pollutants in the aquatic system is essential for protecting the ecological niche. In this work, a highly robust protein nanoparticles networked rare-earth metal carbonate-grafted bio-composite membrane (abbreviated as REMC) was fabricated via chemical crosslinking of three-dimensional (3D) hierarchical lanthanum carbonate (mREM) and casein nanoparticles (CsNPs) for selective rejection of non-reactive phosphates. The main components of the REMC membrane are mREM and CsNPs, which were prepared via SDS/CTAB templated homogeneous precipitation and the coacervation/desolvation hybrid method, respectively. The active lanthanum ion (La³⁺) on the 3D spherulitic surface of mREM exhibited excellent phosphate adsorption capacity (maximum adsorption capacity was 358 mg.g^-1) across a wide pH range and in a multi-ionic environment. A series of batch testing and characterizations revealed that the active La³⁺ and dominating phosphate centers in the REMC membrane framework enable non-enzymatic phosphatase-like activity, cleaving the phosphate ester bond of organic phosphates and releasing free phosphate anions. These released phosphate ions are retained in the REMC membrane via an ion exchange mechanism, where they contribute to improved phosphate removal capacities. Furthermore, CsNPs have a dual function in the membrane, acting as a matrix in the REMC membrane framework and contributing to phosphate ion sequestrations in a synergistic manner. The catalysis of para-nitrophenyl phosphates (pNPP) to paranitrophenol (pNP) in a sequential dephosphorylation by REMC offers an estimate of reaction kinetics and elucidates the underlying mechanism of improved phosphate selectivity in a multi-ionic environment. Furthermore, phosphate specificity, homogeneous binding capacity, reusability, and visual observation of REMC membrane saturation binding direct it's useful economic, industrial applications in aqueous phosphate contaminant removal, which could be beneficial for the active recovery of the aquatic ecosystem.

Formulation and In Vitro Evaluation of Casein Nanoparticles as Carrier for Celecoxib

Purpose: The objective of this work was to formulate casein (CAS) nanocarriers for the dissolution enhancement of poorly water soluble drug celecoxib (CLXB).

Methods: The CLXB loaded CAS nanocarriers viz., nanoparticles, reassembled CAS micelles and nanocapsules were prepared using sodium caseinate (SOD-CAS) as a carrier to enhance the solubility of CLXB. The prepared formulations were characterized for particle size, polydispersity index, zeta potential, percentage entrapment efficiency, and surface morphology for the selection of best formulation. Fourier transform infrared spectroscopy, differential scanning calorimetry and X-ray powder diffraction study was used to for the confirmation of encapsulation of CLXB. Further,in vitro drug dissolution, ex-vivo permeation studies on chicken ileum and stability studies were carried out.

Results: The CLXB loaded casein nanoparticles (CNP) (batch A2) showed a particle size diameter 216.1 nm, polydispersity index 0.422 with percentage entrapment efficiency of 90.71% and zeta potential of -24.6 mV. Scanning electron microscopy of suspension confirmed globular shape of CNP. Thein vitro release data of optimized batch followed non Fickian diffusion mechanism. The ex vivo permeation studies on chicken ileum of CLXB loaded CNP showed permeation through mucous membrane as compared to pure CLXB. The apparent permeability of best selected freeze dried CLXB loaded CNP (batch A2) was higher and gradually increased from 0.90 mg/cm² after 10 min to a maximum of 1.95 mg/cm² over the subsequent 90 min. A higher permeation was recorded at each time point than that of the pure CLXB.

Conclusion: The study explored the potential of CAS as a carrier for solubility enhancement of poorly water soluble drugs.

Mathematical Modeling and Release Kinetics of Green Tea Polyphenols Released from Casein Nanoparticles

Drug release kinetics plays an important role in determining the mechanism of drug release, which in turn helps in formulating controlled/sustained release formulations. In our study, different concentrations of green tea polyphenols (GTP) were encapsulated into casein nanoparticles which showed a maximum encapsulation efficiency (76.9%) at a GTP concentration of 5 mg/mL. The casein nanoparticles were characterized through particle size analysis, zeta potential, AFM, and HR SEM, followed by molecular docking studies, which confirmed the binding of GTP to casein nanoparticles. In-vitro release studies carried out at different temperatures and pH showed no significant difference in the release pattern, but the release was prolonged even up to 48 h. On varying pH of the release medium, an increase in the percentage of release was observed as the pH shifted from acidic to basic. All release data showed good correlation with Zero order kinetics, an ideal model for release of drugs from nanoparticulate sustained release formulations, with anomalous mode of drug transport. Antioxidant activity of the released GTP determined through DPPH assay showed potent antioxidant effect of GTP even after 48 h of its release. Our data indicated that casein nanoparticles could be used as a potent vehicle for the delivery of GTP for achieving a sustained release.

Casein nanoparticles as oral delivery carriers of mequindox for the improved bioavailability

Mequindox (Meq) is a promising broad-spectrum antibacterial agent, but the clinical application of Meq has been hampered by its low oral bioavailability. Casein (Cas) can bind to a variety of poorly water-soluble drugs to improve their water solubility through a micellar solubilization mechanism. Here, a low-cost and convenient method was introduced to prepare mequindox-loaded casein nanoparticles (Meq-Cas). Meq-Cas was characterized by several methods including differential scanning calorimetry (DSC), X-ray diffraction (XRD), and fourier transform infrared (FTIR) to illuminate the mutual effect between the drug and carriers. Meq-Cas presented nearly spherical nanoparticles with smooth surfaces and its mean particle size was lower than untreated Cas. Meq-Cas showed a nearly complete release of Meq, which displayed a biphasic drug release pattern in both phosphate-buffered solution (PBS) and simulated gastric fluid (SGF). The relative oral bioavailability of Meq-Cas was found to be about 1.20 times higher than that of the animals treated with Meq suspension (control). These results suggest that Cas is a good candidate to load in Meq for pharmaceutical purposes.

Doxorubicin-loaded casein nanoparticles for drug delivery: Preparation, characterization and in vitro evaluation

Casein, a milk protein that self-assembles to form micelles in aqueous solution, can bind to a wide range of drugs (hydrophilic and hydrophobic). Herein, a low cost and facile method was reported to prepare casein nanoparticles loaded with an anticancer drug, doxorubicin (DOX). The particles were fabricated by adding an excess of Ca²⁺ ions which brings the soluble casein present in the solution into the micellar framework to form dense nanoparticles. The binding between the drug and the macromolecule was confirmed using fluorescence studies. Circular Dichroism (CD) shows that upon addition of excess Ca²⁺ the protein chains rearrange. The nanoparticles were characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and dynamic light scattering (DLS). The release at pH 1 was higher than the physiological pH making this formulation potent for delivering the drug to the stomach via the oral route. The DOX attached with casein showed improved efficacy, i.e., better cytotoxicity against human pancreatic carcinoma cell line, PANC 1 cells as compared to the free drug of the same concentration, owing to higher cell uptake of the macromolecule.