Stimuli‐responsive materials in general and pH‐responsive polymers in particular have gained increasing interest during the last two decades. Their unique properties, which arise from their ability to exhibit sharp and reversible changes in response to environmental pH conditions, have made them suitable for various applications such as drug delivery and specific body‐site targeting, sensing and actuation, membrane functionalization, separation techniques, as well as in agriculture and food industry and even chemical industries. In the present review, the focus is on the general characteristics of pH‐responsive polymers in terms of their origin, chemical composition, and preparation. Moreover, some of the important and recent applications are reported and discussed.

In the last few years, essential oils (EOs) derived from plants have aroused great interest due to their well-known antimicrobial activity. Unfortunately, they present several limitations in their use, such as photosensitivity, temperature sensitivity, high volatility, and poor water solubility. The encapsulation technique represents a good solution to these problems and ensures protection of the functional properties of essential oils. In this work, bergamot essential oil (BEO) and sweet orange essential oil (OEO) loaded-Eudragit® RS 100 (EuRS100) nanoparticles (NPs) were prepared by using the nanoprecipitation technique. We obtained nanoparticles characterized by a mean diameter of 57 to 208 nm and a positive surface charge (39 to 74 mV). The antibacterial activity of the obtained systems against Escherichia coli was in vitro investigated. We demonstrated that both orange and bergamot essential oils were successfully encapsulated and our nanoparticles have good antibacterial activity. Finally, in order to evaluate the potential applicability of OEONps to prolong fresh orange juice shelf-life, survival of E. coli during a storage period of one week at 25 °C was investigated: Orange essential oil-loaded nanoparticles (OEONPs) have been able to prolong the orange juice shelf life.

The resolution of the Population Balance Equation (PBE) using moment-based methods offers a high computational efficiency however, information on the time evolution of the probability density function (PDF) is out of reach. For this, several PDF reconstruction methods using a finite number of moments are proposed in the literature. In this contribution, three different methods (i.e. Beta Kernel Density Function based method, Spline based technique and the Maximum Entropy based approach) are tested and compared to the analytical solution of a depolymerization process. The Maximum Entropy method gives the most accurate approximations using only a set of six moments. This method is combined with the Quadrature Method of Moments (QMOM) for a simultaneous reconstruction during the PBE resolution. A three nodes and a four nodes quadrature are tested. The results show that the quality of the reconstruction is highly dependent on the accuracy of the computed moments.

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Fungal infections in immune-compromised patients are an important cause of mortality and morbidity. Amphotericin B (Amp B) is considered a powerful fungicidal drug but its clinical usage has certain limitations when administered intravenously due to its toxicity and poor solubility. In consideration of such challenges, in cutaneous leishmaniasis, the topical application of Amp B can be a safer option in many aspects. Thus, herein, biopolymer of polycaprolactone (PCL) nanoparticles (NPs) were developed with the loading of Amp B by nanoprecipitation for the treatment of topical leishmanial infections. Various parameters, such as concentration of PCL and surfactant Poloxamer 407, were varied in order to optimize the formation of nanoparticles for the loading of Amp B. The optimized formulation exhibited a mean hydrodynamic particle size of 183 nm with a spherical morphology and an encapsulation efficiency of 85%. The applications of various kinetic models reveal that drug release from nanoformulation follows Korsmeyer–Peppas kinetics and has a high diffusion exponent at a physiological pH of 7.4 as well a skin relevant pH = 5.5. The activity of the prepared nanoparticles was also demonstrated in Leishmania infected macrophages. The measured IC50 of the prepared nanoparticle formulation was observed to be significantly lower when compared to control free Amp B and AmBisome® for both L. tropica KWH23 and L. donovani amastigotes in order to demonstrate maximum parasite inhibition. The prepared topical nanoformulations are capable of providing novel options for the treatment of leishmaniasis, which can be possible after in vivo assays as well as the establishment of safety profiles.

In this numerical work, a population balance‐based model is proposed in order to describe the cellulose particles size evolution during the enzymatic hydrolysis. Two kinds of actions are considered: endoglucanase activity that cleaves randomly β‐1,4‐glycosidic linkages of cellulose, and exoglucanase activity which reduces the particles size with chain‐end‐cleaving producing cellobiose (a dimer of two glucoses linked by a β‐1,4‐glycosidic bond). A discretization method with a fixed pivot technique is used for the endoglucanase action and a moving pivot technique for exoglucanase attack. The numerical resolution is then validated by analytical solutions available in literature. Afterwards, the combination of the two actions is investigated for different enzyme ratios in order to reproduce the endo‐exo synergism numerically. Since the biodegradation of cellulose releases D‐glucose as a final product due to β‐glucosidase which hydrolyzes cellobiose into two molecules of glucose, numerical kinetic model predicting the fractional conversion of cellulose is derived from the population balance developed model. The enzymes activity is strongly affected by the accumulation of the end‐products (cellobiose and glucose) during the hydrolysis, the inhibition effect is thereby incorporated in the model. The numerical model prediction is compared to experimental data in the case of combined activity and shows a promising approach for the modelling of cellulose‐cellulase systems.

This work deals with the numerical and experimental investigation of droplets breakage in SMX+ static mixers. While steady-state empirical correlations are commonly used for the prediction of the mean droplets size (e.g. Sauter mean diameter) during emulsification in static mixers, in the present study, a population balance equation (PBE) -based model is developed for the prediction of the dynamic evolution of the droplet size distribution (DSD). The system silicon oil-in-water stabilized by Polysorbate 20 (Tween20 R ) is considered under dilute conditions (< 5%vol.). Due to the physico-chemical properties of the system and the operating conditions, the droplets breakage process is dominant, while coalescence and Ostwald ripening are negligible. The breakage kernel proposed by Alopaeus et al. [1] is employed and its parameters are identified and validated for the present system under different operating conditions. The effects of the number of SMX+ elements, viscosity and fraction of the dispersed phase, the DSD at the inlet of the mixers as well as the volume-average energy dissipation rate within the SMX+ elements on the evolution of the DSD are investigated. The model was found to be able of predicting the DSD over a wide range of operating conditions.

The study aims to prepare a smart copolymeric for controlled delivery of Galantamine hydrobromide. The synthesis of the hydrogel was executed through free radical polymerization using HPMC (Hydroxypropyl methylcellulose) and pectin as polymers and acrylic acid as monomer. Cross-linking was performed by methylene bisacrylamide (MBA). HPMC-pectin-co-acrylic acid hydrogel was loaded with Galantamine hydrobromide (antidementia drug) as a model drug for treatment of Alzheimer based dementia. Formulated hydrogels (SN1–SN9) were characterized for Fourier transform-infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction, and energy dispersive X-ray. Drug loading efficiency, gel fraction, measurements of porosity, and tensile strength were reported. Swelling and release studies were performed at pH 1.2 and 7.4. Drug liberation mechanism was evaluated by applying different release kinetic models. Galantamine hydrobromide was released from prepared hydrogels by Fickian release mechanism. Swelling, gel fraction, porosity, and drug release percentages were found to be dependent on hydroxypropyl methylcellulose, pectin, acrylic acid, and methylene bisacrylamide concentrations. By increasing HPMC amount, swelling was increased from 76.7% to 95.9%. Toxicity studies were conducted on albino male rabbits for a period of 14 days. Hematological and histopathological studies were carried out to evaluate safety level of hydrogel. Successfully prepared HPMC-pectin-co-acrylic acid hydrogel showed good swelling and release kinetics, which may help greatly in providing controlled release drug effect leading to enhanced patient compliance for dementia patients.