Surface Modification of SPIONs in PHBV Microspheres for Biomedical Applications

Active Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) Films Containing Phenolic Compounds with Different Molecular Structures

To obtain more sustainable and active food packaging materials, PHBV films containing 5% wt. of phenolic compounds with different molecular structures (ferulic acid, vanillin, and catechin) and proved antioxidant and antimicrobial properties were obtained by melt blending and compression molding. These were characterized by their structural, mechanical, barrier, and optical properties, as well as the polymer crystallization, thermal stability, and component migration in different food simulants. Phenolic compounds were homogenously integrated within the polymer matrix, affecting the film properties differently. Ferulic acid, and mainly catechin, had an anti-plasticizing effect (increasing the polymer glass transition temperature), decreasing the film extensibility and the resistance to breaking, with slight changes in the elastic modulus. In contrast, vanillin provoked a plasticizing effect, decreasing the elastic modulus without notable changes in the film extensibility while increasing the water vapor permeability. All phenolic compounds, mainly catechin, improved the oxygen barrier capacity of PHBV films and interfered with the polymer crystallization, reducing the melting point and crystallinity degree. The thermal stability of the material was little affected by the incorporation of phenols. The migration of passive components of the different PHBV films was lower than the overall migration limit in every simulant. Phenolic compounds were released to a different extent depending on their thermo-sensitivity, which affected their final content in the film, their bonding forces in the polymer matrix, and the simulant polarity. Their effective release in real foods will determine their active action for food preservation. Catechin was the best preserved, while ferulic acid was the most released.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Blends with Poly(caprolactone) and Poly(lactic acid): A Comparative Study

Poly(hydroxybutyrate-co-hidroxyvalerate) (PHBV) is a biodegradable polymer, which is a potential substitute for plastics made from fossil resources. Due to its practical interest in the field of tissue engineering, packaging, sensors, and electronic devices, the demand for PHBV with specific thermal, electrical, as well as mechanical requirements is growing. In order to improve these properties, we have developed PHBV blends with two thermoplastic biodegradable polyesters, including poly(caprolactone) (PCL) and poly(lactic acid) (PLA). We analysed the effect of these biopolymers on the morphological, wetting, structural, thermal, mechanical, and electrical characteristics of the materials. Further, the biodegradation of the samples in simulated body fluid conditions was evaluated, as well as the antibacterial activity. The results demonstrate that the blending with PCL and PLA leads to films with a dense morphology, increases the hydrophilic character, and induces a reinforcement of the mechanical characteristics with respect to pristine PHBV. In addition, a decrease in dielectric constant and a.c. electrical conductivity was noticed for PHBV/PLA and PHBV/PCL blends compared to neat PHBV polymer. All neat polymers and blends showed antibacterial properties against S. aureus, with more than 40% bacterial reduction, which increased to 72% in the presence of PCL polymer for a blend ratio of 50/50. Thus, it is demonstrated a suitable way to further tailor a variety of functionalities of PHBV for specific applications, by the development of polymer blends with PLA or PCL.

Overview of Antimicrobial Biodegradable Polyester-Based Formulations

As the clinical complications induced by microbial infections are known to have life-threatening side effects, conventional anti-infective therapy is necessary, but not sufficient to overcome these issues. Some of their limitations are connected to drug-related inefficiency or resistance and pathogen-related adaptive modifications. Therefore, there is an urgent need for advanced antimicrobials and antimicrobial devices. A challenging, yet successful route has been the development of new biostatic or biocide agents and biomaterials by considering the indisputable advantages of biopolymers. Polymers are attractive materials due to their physical and chemical properties, such as compositional and structural versatility, tunable reactivity, solubility and degradability, and mechanical and chemical tunability, together with their intrinsic biocompatibility and bioactivity, thus enabling the fabrication of effective pharmacologically active antimicrobial formulations. Besides representing protective or potentiating carriers for conventional drugs, biopolymers possess an impressive ability for conjugation or functionalization. These aspects are key for avoiding malicious side effects or providing targeted and triggered drug delivery (specific and selective cellular targeting), and generally to define their pharmacological efficacy. Moreover, biopolymers can be processed in different forms (particles, fibers, films, membranes, or scaffolds), which prove excellent candidates for modern anti-infective applications. This review contains an overview of antimicrobial polyester-based formulations, centered around the effect of the dimensionality over the properties of the material and the effect of the production route or post-processing actions.

Evaluation of Heavy Metal Removal of Nanoparticles Based Adsorbent Using Danio rerio as Model

Nanoparticles are potential candidates for wastewater treatment especially for the removal of heavy metals due to their strong affinity. Many biopolymers are used as adsorbents and encapsulation of nanoparticle onto them can increase their efficiency. In this study, SPIONs, alginate, and SPIONs incorporated on alginate beads have been synthesized and characterized both microscopically and spectroscopically. These were then used for the removal of chromium metal and the percentage of removal was evaluated using a batch adsorption study. The percent removal of chromium using SPIONs, alginate and alginate-SPIONs beads were recorded to be 93%, 91% and 94%, respectively. The adsorption of chromium using SPIONs and alginate-SPIONs beads followed the Tempkin isotherm, whereas adsorption of chromium metal by alginate beads was found to be homogeneous in nature and followed the Langmuir isotherm with an R² value of 0.9784. An in-vivo study using Danio rerio as a model organism was done to examine the toxicity and the removal efficiency of the samples. It was observed that chromium water treated with alginate-SPIONs beads, which were removed after water treatment showed less damage to the fishes when compared to SPIONs and alginate beads treated with chromium water where the SPIONs and alginate beads were not removed after the treatment period.

Engineering alginate hydrogel films with poly(3-hydroxybutyrate-co-3-valerate) and graphene nanoplatelets: Enhancement of antiviral activity, cell adhesion and electroactive properties

A new biodegradable semi-interpenetrated polymer network (semi-IPN) of two US Food and Drug Administration approved materials, poly(3-hydroxybutyrate-co-3-valerate) (PHBV) and calcium alginate (CA) was engineered to provide an alternative strategy to enhance the poor adhesion properties of CA. The synthesis procedure allows the additional incorporation of 10 % w/w of graphene nanoplatelets (GNPs), which have no cytotoxic effect on human keratinocytes. This quantity of multilayer graphene provides superior antiviral activity to the novel semi-IPN against a surrogate virus of SARS-CoV-2. Adding GNPs hardly affects the water absorption or electrical conductivity of the pure components of CA and PHBV. However, the semi-IPN's electrical conductivity increases dramatically after adding GNP due to molecular rearrangements of the intertwined polymer chains that continuously distribute the GNP nanosheets, This new hydrophilic composite biomaterial film shows great promise for skin biomedical applications, especially those that require antiviral and/or biodegradable electroconductive materials.

Development of an antibiotics delivery system for topical treatment of the neglected tropical disease Buruli ulcer

Skin infection by Mycobacterium ulcerans causes Buruli ulcer (BU) disease, a serious condition that significantly impact patient' health and quality of life and can be very difficult to treat. Treatment of BU is based on daily systemic administration of antibiotics for at least 8 weeks and presents drawbacks associated with the mode and duration of drug administration and potential side effects. Thus, new therapeutic strategies are needed to improve the efficacy and modality of BU therapeutics, resulting in a more convenient and safer antibiotic regimen. Hence, we developed a dual delivery system based on poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) microparticles and a gellan gum (GG) hydrogel for delivery of rifampicin (RIF) and streptomycin (STR), two antibiotics used for BU treatment. RIF was successfully loaded into PHBV microparticles, with an encapsulation efficiency of 43%, that also revealed a mean size of 10 µm, spherical form and rough topography. These microparticles were further embedded in a GG hydrogel containing STR. The resultant hydrogel showed a porous microstructure that conferred a high water retention capability (superior to 2000%) and a controlled release of both antibiotics. Also, biological studies revealed antibacterial activity against M. ulcerans, and a good cytocompatibility in a fibroblast cell line. Thus, the proposed drug delivery system can constitute a potential topical approach for treatment of skin ulcers caused by BU disease.

Biosynthesis of folic acid appended PHBV modified copper oxide nanorods for pH sensitive drug release in targeted breast cancer therapy

Multifunctional nanoplatforms as nanocarriers have attracted the interest of many scientists because they can achieve greater therapeutic effect in anticancer drug delivery to tumors with potential to improve cancer treatment, while currently available therapies are nonspecific and ineffectual. In present study, notable cancer therapeutic strategy which combines PEG functionalized poly (3-hydroxybutyric acid-co-hydroxyvaleric acid) (PHBV) nanospheres decorated with folic acid for delivery of paclitaxel (PTX) drug conjugated with copper oxide (CuO) nanoparticles (NPs) is proposed. Moreover, PTX loading with CuO NPs in PHBV nanosphere was done to increase its solubility and analyze its apoptotic effects in human breast cancer (MCF-7) cells. The pH-sensitive CuO-PTX@PHBV-PEG-FA nanosystem was successfully developed, as evidenced by number of characterizations. Resultant CuO-PTX@PHBV-PEG-FA NPs were 148.93 ± 10.5 nm in size, having 0.206 PDI, with -20.3 ± 0.6 mV zeta potential. MTT assay in MCF-7 cells was used to assess cell viability, while anticancer potential of CuO-PTX@PHBV-PEG-FA nanosystem was confirmed through different staining techniques. According to invitro studies, FA-conjugated PHBV modified CuO-PTX targeted nanoparticles exhibited higher anticancer effect than free PTX probably due to binding interaction of folate receptor with cells that overexpress the target. This nanosystem has the potential to be a promising breast cancer treatment agent.

Fabrication, microstructure characterization, and degradation performance of electrospun mats based on poly(3-hydroxybutyrate-co-3 hydroxyvalerate)/polyethylene glycol blend for potential tissue engineering

There have been strong demands for nanofibrous scaffolds fabricated by electrospinning for various fields due to their various advantages. Electrospun poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) fibre mats were prepared. The effects of processing variables as well as the inclusion of poly(ethylene glycol) (PEG) on the morphologies of generated fibres were investigated using Fourier-transform infrared spectroscopy and scanning electron microscopy. The average fibrous diameter was monitored in the range 400-3000 nm relying on the total content of PEG. The fluorescence cell imaging of electrospun mats was also explored. The results of cell viability demonstrated that skin fibroblast BJ-1 cells showed different adhesions and growth rates for the three kinds of PHBV fibres. Electrospun PHBV mats with low amount of PEG offer a high-quality medium for cell growth. Therefore, those mats exhibited high potential for soft tissue engineering, in particular wound healing.

A Tri-Stimuli Responsive (Maghemite/PLGA)/Chitosan Nanostructure with Promising Applications in Lung Cancer

A (core/shell)/shell nanostructure (production performance ≈ 50%, mean diameter ≈ 330 nm) was built using maghemite, PLGA, and chitosan. An extensive characterization proved the complete inclusion of the maghemite nuclei into the PLGA matrix (by nanoprecipitation solvent evaporation) and the disposition of the chitosan shell onto the nanocomposite (by coacervation). Short-term stability and the adequate magnetism of the nanocomposites were demonstrated by size and electrokinetic determinations, and by defining the first magnetization curve and the responsiveness of the colloid to a permanent magnet, respectively. Safety of the nanoparticles was postulated when considering the results from blood compatibility studies, and toxicity assays against human colonic CCD-18 fibroblasts and colon carcinoma T-84 cells. Cisplatin incorporation to the PLGA matrix generated appropriate loading values (≈15%), and a dual pH- and heat (hyperthermia)-responsive drug release behaviour (≈4.7-fold faster release at pH 5.0 and 45 °C compared to pH 7.4 and 37 °C). The half maximal inhibitory concentration of the cisplatin-loaded nanoparticles against human lung adenocarcinoma A-549 cells was ≈1.6-fold less than that of the free chemotherapeutic. Such a biocompatible and tri-stimuli responsive (maghemite/PLGA)/chitosan nanostructure may found a promising use for the effective treatment of lung cancer.

Solid-in-Oil-in-Water Emulsion: An Innovative Paradigm to Improve Drug Stability and Biological Activity

Abstract

An emulsion is a biphasic dosage form comprising of dispersed phase containing droplets that are uniformly distributed into a surrounding liquid which forms the continuous phase. An emulsifier is added at the interface of two immiscible liquids to stabilize the thermodynamically unstable emulsion. Various types of emulsions such as water-in-oil (w-o), oil-in-water (o-w), microemulsions, and multiple emulsions are used for delivering certain drugs in the body. Water (aqueous) phase is commonly used for encapsulating proteins and several other drugs in water-in-oil-in-water (w-o-w) emulsion technique. But this method has posed certain problems such as decreased stability, burst release, and low entrapment efficiency. Thus, a novel “solid-in-oil-in-water” (s-o-w) emulsion system was developed for formulating certain drugs, probiotics, proteins, antibodies, and tannins to overcome these issues. In this method, the active ingredient is encapsulated as a solid and added to an oil phase, which formed a solid-oil dispersion. This dispersion was then mixed with water to form a continuous phase for enhancing the drug absorption. This article focuses on the various studies done to investigate the effectiveness of formulations prepared as solid-oil-water emulsions in comparison to conventional water-oil-water emulsions. A summary of the results obtained in each study is presented in this article. The s-o-w emulsion technique may become beneficial in near future as it has shown to improve the stability and efficacy of the entrapped active ingredient.

Graphical abstract

Shaping Magnetite by Hydroxyl Group Numbers of Small Molecules

Despite numerous reports on magnetite formation with the assistance of various additives, the role of hydroxyl group (-OH) numbers in small polyol molecules has not yet been understood well. We selected small molecules containing different -OH numbers, such as ethanol, ethylene glycol, propanetriol, butanetetrol, pentitol, hexanehexol, and cyclohexanehexol, as additives in coprecipitation. By increasing the -OH number in these small polyol molecules, the formation of crystallization was slowed, and the size and shape of magnetite were regulated as well possibly due to the changed complexation strength and the stability of the precursor. The increase in temperature and the Fe²⁺/Fe³⁺ ratio can reduce the complexation strength. The nucleation and growth of magnetite proceed possibly through the aggregation of polyol-stabilized amorphous complexes and two-line ferrihydrite with low crystallinity based on the -OH numbers, suggesting a nonclassical pathway. The as-prepared magnetite showed a r₂/r₁ ratio after in vitro MRI measurement as follows: Fe₃O₄@He-6OH rod < Fe₃O₄@Pr-3OH sheet < Fe₃O₄@Pe-5OH cube. The Fe₃O₄@He-6OH rod and Fe₃O₄@Pr-3OH sheet displayed T₁-T₂ dual modal contrast ability, while the Fe₃O₄@Pe-5OH cube can be T₂-dominated. This research provides a simple but an essential approach for designing MRI contrast agents.

Nanocarriers for effective nutraceutical delivery to the brain

Neurodegenerative disorders are common among aging populations around the globe. Most are characterized by loss of neurons, protein aggregates, oxidative stress, mitochondrial damage, neuroinflammation among others. Although symptomatic treatment using conventional pharmacotherapy has been widely employed, their therapeutic success is limited due to varied reasons. In the need to identify an alternative approach, researchers successfully demonstrated the therapeutic utility of plant-derived nutraceuticals in cell and animal models of neurodegenerative conditions. However, most nutraceuticals failed during clinical trials in humans owing to their poor bioavailability in vivo and limited permeability across the blood brain barrier (BBB). The current emphasis is therefore on the improved delivery of nutraceuticals to the brain. In this regard, development of nanoparticle conjugated nutraceuticals to enhance bioavailability and therapeutic efficacy in the brain has gained attention. Here, we review the research advances in nanoparticles conjugated nutraceuticals applied in neurodegenerative disorders and discuss their advantages and limitations, clinical trials and toxicity concerns.

Structural Regulation of Magnetic Polymer Microsphere@Ionic Liquids with an Intermediate Protective Layer and Application as Core-Shell-Shell Catalysts with High Stability and Activity

A novel ionic liquid immobilized on a magnetic polymer microsphere catalyst is reported in this paper. The obtained core-shell-shell catalyst consisted of magnetic nanoparticles (MNPs) as the core, catalytic inert St-co-DVB as the intermediate protective layer, and cross-linked polyaryl imidazole ionic liquids as the active catalytic layer located at the outermost [Im[OH]/MNPs@P(St-DVB)@P(VBC-DVB)]. This catalyst exhibited a high ion-exchange rate (64.65%), high saturation magnetic strength, and excellent acid and alkali corrosion resistance. In the catalyzed Knoevenagel condensation of benzaldehyde and ethyl cyanoacetate, the conversion of benzaldehyde maintained at 92.1% during six times reuse. Optimizing the materials of the protective layer and regulating the thickness of the inert protective layer decreased the corrosion ratio of MNPs in acidic media from 44.82 to 0.44%. Adjusting the thickness of the catalytic layer realized excellent catalytic activity (97%) and high magnetic response performance. In summary, introducing an inert protective layer to the structure of ionic liquids immobilized on the magnetic polymer microsphere catalyst, regulating its thickness, and optimizing its structure achieved a catalyst with high activity, excellent stability, and easy magnetic separation.

Modeling the release of curcumin from microparticles of poly(hydroxybutyrate) [PHB]

Polyhydroxybutyrate (PHB) is biodegradable and biocompatible polyester that has been recently used for developing different drug delivery systems (DDS). Microspheres as DDS, consist of a polymeric matrix with a diameter of 1-125 μm which contains a substance entrapped, and then released mainly through diffusion. In order to make DDS viable for commercial applications, it is essential to develop models that describe and predict the substance release kinetic. In this study, microspheres of PHB with curcumin entrapped were synthesized; the release of curcumin was studied and modeled. As a first approach, a physical model was introduced, in which mass transference was considered analogous to heat transference. The proposed model was based on local mass balance through the classical diffusion equation and total mass balance imposed through an integro-differential equation. The total mass balance introduced nonlinearities in the dynamics of the drug within the fluid; therefore, a semi-analytical approach based on the heat balance integral method was applied to solve the proposed model. Finally, by using the experimental rate of release of curcumin, the semi-analytical solutions to the proposed model were compared with the experimental release data, showing the importance of adding mass balance in the nonlinear mathematical model in order to describe more accurately the release kinetics.

Biodegradation of polyhydroxybutyrate by Pseudomonas sp. DSDY0501 and purification and characterization of polyhydroxybutyrate depolymerase

Strain DSDY0501 with polyhydroxybutyrate (PHB)-degrading ability was isolated from activated sludge. The morphological, physiological, and biochemical properties of the strain and phylogenetic analysis indicated that the strain belongs to Pseudomonas sp. The strain used PHB as the sole carbon source and degraded PHB films completely in 21 h in liquid culture. An extracellular PHB depolymerase was purified from the supernatant of the culture by ultrafiltration and Sephacryl S-200 gel filtration. The specific activity of the purified enzyme increased 24.2-fold, and the recovery yield was 16.61%. Extracellular PHB depolymerase, a monomeric enzyme with a molecular weight of approximately 57.9 kDa, showed optimum activity at 60 °C and pH 9.0, and was stable in the temperature range of 10-60 °C and a pH range of 6.0-10.0. The secondary structure of the enzyme contained approximately 60% α-helix and 40% β-pleated sheet according to the circular dichroism spectrum. Mass spectrum analysis showed that the main degradation product of the enzyme was PHB monomer, indicating the exo-type action of this PHB depolymerase.

Nanomaterials multifunctional behavior for enlightened cancer therapeutics

Cancer is an outrageous disease with uncontrolled differentiation, growth, and migration to the other parts of the body. It is the second-most common cause of death both in the U.S. and worldwide. Current conventional therapies, though much improved and with better prognosis, have several limitations. Chemotherapeutic agents, for instance, are cytotoxic to both tumor and healthy cells, and the non-specific distribution of drugs at tumor sites limits the dose administered. Nanotechnology, which evolved from the coalescence and union of varied scientific disciplines, is a novel science that has been the focus of much research. This technology is generating more effective cancer therapies to overcome biomedical and biophysical barriers against standard interventions in the body; its unique magnetic, electrical, and structural properties make it a promising tool. This article reviews endogenous- and exogenous-based stimulus-responsive drug delivery systems designed to overcome the limitations of conventional therapies. The article also summarizes the study of nanomaterials, including polymeric, gold, silver, magnetic, and quantum dot nanoparticles. Though an array of drug delivery systems has so far been proposed, there remain many challenges and concerns that should be addressed in order to fill the gaps in the field. Prominence is given to drug delivery systems that employ external- and internal-based stimuli and that are emerging as promising tools for cancer therapeutics in clinical settings.

Targeted delivery of doxorubicin by magnetic mesoporous silica nanoparticles armed with mucin-1 aptamer

Distinctive physicochemical features make mesoporous silica magnetic nanoparticles (SPION@SiO₂) as a multifunctional nanosystem (NS) for the targeted delivery of therapeutic agents. In the present study, we engineered the mucin-1 (MUC-1) conjugated SPION@SiO₂ (SPION@SiO₂-MUC-1) for the targeted delivery of doxorubicin (DOX) to the breast cancer cells. Superparamagnetic iron oxide nanoparticles (SPIONs) were synthesised using thermal decomposition technique, and then, coated with mesoporous silica to modify their biocompatibility and reduce undesired cytotoxic effects. Subsequently, DOX was loaded onto the silica porous structures, which was then nanoparticles (NPs) grafted with 5'-amine-modified MUC-1 aptamers. Transmission electron microscopy and particle size analysis by differential light scattering exhibited spherical and monodisperse NPs with a size range of 5-27 nm. The FT-IR spectroscopy confirmed the surface modification of the engineered NS. The surface area and pore size of the SPION@SiO₂-COOH NSs were calculated by BJH and BET calculations. The MTT assay revealed higher cytotoxicity of MUC-1 grafted SPION@SiO₂ NSs in the MUC-1-positive MCF-7 cells as compared to the control MUC-1-negative MDA-MB-231 cells. The flow cytometry analysis of the SPION@SiO₂-MUC-1 NSs revealed a higher uptake as compared to the non-targeted nanocomposite (NC) in MCF-7 cells. In conclusion, the engineered SPION@SiO₂-MUC-1 NS is proposed to serve as an effective multifunctional targeted nanomedicine/theranostics against MUC-1 overexpressing cancer cells.