Ramin Rohanizadeh

Combination of Silver Nanoparticles and Curcumin Nanoparticles for Enhanced Anti-biofilm Activities

Biofilm tolerance has become a serious clinical concern in the treatment of nosocomial pneumonia owing to the resistance to various antibiotics. There is an urgent need to develop alternative antimicrobial agents or combination drug therapies that are effective via different mechanisms. Silver nanoparticles (AgNPs) have been developed as an anti-biofilm agent for the treatment of infections associated with the use of mechanical ventilations, such as endotracheal intubation. Meanwhile curcumin, a phenolic plant extract, has displayed natural anti-biofilm properties through the inhibition of bacterial quorum sensing systems. The aim of this study was to investigate the possible synergistic/additive interactions of AgNPs and curcumin nanoparticles (Cur-NPs) against both Gram-negative (Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) microorganisms. The combination of AgNPs and Cur-NPs (termed Cur-SNPs) at 100 μg/mL disrupted 50% of established bacterial biofilms (formed on microtiter plates). However, further increase in the concentration of Cur-SNPs failed to effectively eliminate the biofilms. To achieve the same effect, at least 500 μg/mL Cur-NP alone was needed. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) revealed that combination therapy (Cur-SNPs) was the most potent to eradicate preformed biofilm compared to monodrug therapy. These agents are also nontoxic to healthy human bronchial epithelial cells (BEAS2B).

Biomedical applications of cationic clay minerals

Clay minerals have been a subject of interest owing to their ready availability in nature, a wide range of applications in various industries, and particularly their current and potential biomedical applications. They have been widely used for curative and protective purposes by humans since ancient times. Cationic clay minerals possess specific physicochemical characteristics such as high surface reactivity (high adsorption, cation exchange, colloidal or swelling capacity), good rheological behavior, high acid-absorbing capacity, and high dispersibility in water, which renders them suitable for various biomedical applications. Only a few reviews have exclusively discussed the biomedical applications of clay minerals, and to our knowledge, there is no updated review focusing on cationic clay minerals and their applications in pharmaceuticals, cosmetics, and regenerative medicine. In this review, we provide a brief introduction on natural, synthetic, and hybrid cationic clay minerals followed by a detailed discussion about their applications in biological systems.

A new solution for removing metal-based catalyst residues from a biodegradable polymer

The presence of metal-based catalysts in polymers is one of the obstacles for their applications in food packaging and composting. The current processes for removing these compounds are not efficient; they involve several steps and use a large amount of organic solvents and acids. To tackle these issues, we developed a new green approach in which CO2 laden water was used for the extraction of these compounds from a commercial polymer, poly(propylene carbonate) (PPC). Although PPC has favourable properties for food packaging and many other applications, a high level of a metal-based catalyst remains in its matrix after the polymerization. Prior to the extraction process, the solubility of different metal-based compounds in CO2 laden water was measured. Our results demonstrated that at 160 bar and 40 °C the solubility of zinc adipate (ZnAA), zinc glutarate (ZnGA) and zinc methyl glutarate (ZnMGA) was 0.66 mg ml−1, 1.37 mg ml−1, and 1.54 mg ml−1, respectively. Therefore, we attempted to purify PPC containing 2450 ppm ZnGA residue using this technique. Our results demonstrated that CO2 laden water was able to remove nearly 90% of the catalyst from PPC at 70 bar and 45 °C in static mode extraction. The process developed in this study is superior to the current techniques as it not only reduced zinc residues 70% more than the conventional method in the absence of any organic solvent and acid, but it also enabled us to remove other impurities such as cyclic propylene carbonate (cPC). Therefore, this purification technique played a pivotal role in promoting the physico-chemical properties of PPC. For example, after the purification, the thermal decomposition temperature of PPC was shifted from 124 °C to 214 °C which is paramount for thermal processing such as hot-melt extrusion; its tensile modulus increased from 1 MPa to 1.4 MPa, which is critical for packaging and other applications. These results demonstrated that CO2 laden water is an efficient green solvent for removing metallic compounds from a polymer to the acceptable level recommended by environmental protection agencies for composting. It will also open an avenue for broadening the application of renewable polymers for food packaging to address major environmental issues.

Osteoblast response to the surface of amino acid-functionalized hydroxyapatite

Interactions between proteins and the surface of biomaterials are crucial for the biological function and success of materials implanted in the human body. In this study, hydroxyapatite (HA) with negative and positive surface charges were fabricated by functionalizing the HA surface with acidic or basic amino acids. The influence of HA surface charge on protein adsorption and cell activities was studied. The crystallinity, morphology, and surface charge of amino acid-functionalized HA (AA-HA) particles and the stability of amino acids on the HA surface were determined. Both AA-HA and unmodified HA were studied for their capacity to adsorb proteins present in biological medium. The results showed that the presence of glutamic acid; Glu (acidic amino acids) and arginine; Arg (basic amino acids) on the HA surface resulted in higher protein adsorption owing to stronger electrostatic attraction between the HA particles and the proteins in medium. Functionalizing HA with Glu and Arg significantly promoted osteoblast adhesion on the surface of treated HA. No significant differences in cell proliferation between negatively and positively charged HA was observed. Significantly higher alkaline phosphatase (ALP) activity of osteoblasts on both charged surfaces was seen as compared to the unmodified HA. The study demonstrated that immobilization of amino acids (Glu and Arg) on the surface of HA promoted osteoblast proliferation and ALP activity.

Therapeutic actions of curcumin in bone disorders

Curcumin is the active component of turmeric extract derived from the Curcuma longa plant. In the last decade, curcumin has raised a considerable interest in medicine owing to its negligible toxicity and multiple therapeutic actions including anti-cancer, anti-inflammatory and anti-microbial activities. Among the various molecular targets of curcumin, some are involved in bone remodeling, which strongly suggests that curcumin can affect the skeletal system. The review sheds light on the current and potential applications of curcumin to treat bone disorders characterized by an excessive resorption activity. Within the scope of this review, the novel formulations of curcumin to overcome its physico-chemical and pharmacokinetic constraints are also discussed.

The achievement of ligand-functionalized organic/polymeric nanoparticles for treating multidrug resistant cancer

ABSTRACT Introduction: The effectiveness of conventional cancer chemotherapy is hampered by the occurrence of multidrug resistance (MDR) in tumor cells. Although many studies have reported the development of novel MDR chemotherapeutic agents, clinical success is lacking owing to the high associated toxicity. Nanoparticle-based delivery of chemotherapeutic drugs has emerged as alternative approach to treat MDR cancers via exploitation of leaky vasculature in the tumor microenvironment. Accordingly, functionalization of nanoparticles with target specific ligands can be employed to achieve significant improvements in the treatment of MDR cancer. Areas covered: This review focuses on the recent advances in the functionalization of nanocarriers with specific ligands, including antibodies, transferrin, folate, and peptides to overcome MDR cancer. The limitations of effective ligand-functionalized nanoparticles as well as therapeutic successes in ligand targeting are covered in the review. Expert opinion: Targeting MDR tumors with ligand-functionalized nanoparticles is a promising approach to improve the treatment of cancer. With this approach, higher drug concentrations at targeted sites would be achieved with lower dosage frequencies and reduced side effects in comparison to existing formulations of chemotherapeutic drugs. However, potential toxicities and immunological responses to ligands should be carefully reviewed for viable options in for future MDR cancer treatment.

Implications and emerging control strategies for ventilator-associated infections

Ventilator-associated pneumonia (VAP) remains a major burden to the healthcare system and intubated patients in intensive care units. In fact, VAP is responsible for at least 50% of prescribed antibiotics to patients who need mechanical ventilation. One of the factors contributing to VAP pathogenesis is believed to be rapid colonization of biofilm-forming pathogens such as Pseudomonas aeruginosa and Staphylococcus aureus on the surface of inserted endotracheal tubes. These biofilms serve as a protective environment for bacterial colonies and provide enhanced resistance towards many antibiotics. This review presents and discusses an overview of current strategies to inhibit the colonization and formation of biofilm on endotracheal tubes, including antibiotic treatment, surface modification and antimicrobial agent incorporation onto endotracheal tube materials.

Curcumin Nanoparticles Attenuate Production of Pro-inflammatory Markers in Lipopolysaccharide-Induced Macrophages

ABSTRACTPurposeThe surface charge of nanoparticles is an important factor that controls efficiency and cellular uptake. The aim of this study was to investigatexa0the efficacy of curcumin nanoparticles (Cur-NPs) with different surface charges, in terms of toxicity, internalization, anti-inflammatory and anti-oxidant activities towards alveolar macrophages cells.MethodsThe surface charge of curcumin nanoparticles (positive, negative and neutral), with an average diameter of 30xa0nm, were synthesized and characterized. Polyvinyl-alcohol, polyvinylpyrrolidone and dextran were used as coatings to confer negative, positive and neutral charges. The synthesized Cur-NPs were evaluated for particle size, encapsulation efficiency, surface charge, qualitative and quantitative cellular uptakes, anti-oxidant and anti-inflammatory activities.ResultsPositively charged nanoparticles showed higher cytotoxicity effects compared to negative and neutral particles. The same trend was observed in antioxidant activity, which included radical scavenging and nitric oxide production. In addition, the anti-inflammatory activity (interleukin-1β, IL-6 and TNF-α) depleted in the order: positive>negative>neutral. The void neutral-, positively- and negatively-charged nanoparticles did not show any cytotoxic effects.ConclusionThe difference in activity for different surface charges of Cur-NPs may be due to the internalization rate of the particles by alveolar macrophages. Intracellular uptake measurements demonstrated that Cur-NPs with positive surface charges possessed the strongest interaction with alveolar macrophages.