New Fe3O4-Based Coatings with Enhanced Anti-Biofilm Activity for Medical Devices.

With the increasing use of invasive, interventional, indwelling, and implanted medical devices, healthcare-associated infections caused by pathogenic biofilms have become a major cause of morbidity and mortality. Herein, we present the fabrication, characterization, and in vitro evaluation of biocompatibility and anti-biofilm properties of new coatings based on Fe3O4 nanoparticles (NPs) loaded with usnic acid (UA) and ceftriaxone (CEF). Sodium lauryl sulfate (SLS) was employed as a stabilizer and modulator of the polarity, dispersibility, shape, and anti-biofilm properties of the magnetite nanoparticles. The resulting Fe3O4 functionalized NPs, namely Fe3O4@SLS, Fe3O4@SLS/UA, and Fe3O4@SLS/CEF, respectively, were prepared by co-precipitation method and fully characterized by XRD, TEM, SAED, SEM, FTIR, and TGA. They were further used to produce nanostructured coatings by matrix-assisted pulsed laser evaporation (MAPLE) technique. The biocompatibility of the coatings was assessed by measuring the cell viability, lactate dehydrogenase release, and nitric oxide level in the culture medium and by evaluating the actin cytoskeleton morphology of murine pre-osteoblasts. All prepared nanostructured coatings exhibited good biocompatibility. Biofilm growth inhibition ability was tested at 24 h and 48 h against Staphylococcus aureus and Pseudomonas aeruginosa as representative models for Gram-positive and Gram-negative bacteria. The coatings demonstrated good biocompatibility, promoting osteoblast adhesion, migration, and growth without significant impact on cell viability or morphology, highlighting their potential for developing safe and effective antibacterial surfaces.

Organic Nanoparticles in Progressing Cardiovascular Disease Treatment and Diagnosis.

Cardiovascular diseases (CVDs), the world's most prominent cause of mortality, continue to be challenging conditions for patients, physicians, and researchers alike. CVDs comprise a wide range of illnesses affecting the heart, blood vessels, and the blood that flows through and between them. Advances in nanomedicine, a discipline focused on improving patient outcomes through revolutionary treatments, imaging agents, and ex vivo diagnostics, have created enthusiasm for overcoming limitations in CVDs' therapeutic and diagnostic landscapes. Nanomedicine can be involved in clinical purposes for CVD through the augmentation of cardiac or heart-related biomaterials, which can be functionally, mechanically, immunologically, and electrically improved by incorporating nanomaterials; vasculature applications, which involve systemically injected nanotherapeutics and imaging nanodiagnostics, nano-enabled biomaterials, or tissue-nanoengineered solutions; and enhancement of sensitivity and/or specificity of ex vivo diagnostic devices for patient samples. Therefore, this review discusses the latest studies based on applying organic nanoparticles in cardiovascular illness, including drug-conjugated polymers, lipid nanoparticles, and micelles. Following the revised information, it can be concluded that organic nanoparticles may be the most appropriate type of treatment for cardiovascular diseases due to their biocompatibility and capacity to integrate various drugs.

Special Issue: "Functionalized Nanomaterials and Structures for Biomedical Applications".

Nanoscale drug formulations are under wider and wider investigation due to their multiple unique advantages, such as stealth properties which avoid opsonization in the blood stream; specific ligand guided drug delivery to injured cells and tissues; on-demand release in sharp response to a series of endogenous and exogenous stimuli, allowing for predetermined programmed delivery to specific loci in the body and possible timing with circadian rhythms; increased cellular uptake due to their small dimensions and the possibility of intracellular delivery of the therapeutic cargo, especially when functionalized with cell penetrating agents; increased stability in biological fluids; augmented bioavailability; and tailored pharmacokinetics and pharmacodynamics [...].

Multifunctional Polymeric Biodegradable and Biocompatible Coatings Based on Silver Nanoparticles: A Comparative In Vitro Study on Their Cytotoxicity towards Cancer and Normal Cell Lines of Cytostatic Drugs versus Essential-Oil-Loaded Nanoparticles and on Their Antimicrobial and Antibiofilm Activities.

We report on a comparative in vitro study of selective cytotoxicity against MCF7 tumor cells and normal VERO cells tested on silver-based nanocoatings synthesized by the matrix-assisted pulsed laser evaporation (MAPLE) technique. Silver nanoparticles (AgNPs) were loaded with five representative cytostatic drugs (i.e., doxorubicin, fludarabine, paclitaxel, gemcitabine, and carboplatin) and with five essential oils (EOs) (i.e., oregano, rosemary, ginger, basil, and thyme). The as-obtained coatings were characterized by X-ray diffraction, thermogravimetry coupled with differential scanning calorimetry, Fourier-transform IR spectroscopy, IR mapping, and scanning electron microscopy. A screening of the impact of the prepared nanocoatings on the MCF7 tumor and normal VERO cell lines was achieved by means of cell viability MTT and cytotoxicity LDH assays. While all nanocoatings loaded with antitumor drugs exhibited powerful cytotoxic activity against both the tumor and the normal cells, those embedded with AgNPs loaded with rosemary and thyme EOs showed remarkable and statistically significant selective cytotoxicity against the tested cancercells. The EO-loaded nanocoatings were tested for antimicrobial and antibiofilm activity against Staphylococcus aureus, Escherichia coli, and Candida albicans. For all studied pathogens, the cell viability, assessed by counting the colony-forming units after 2 and 24 h, was significantly decreased by all EO-based nanocoatings, while the best antibiofilm activity was evidenced by the nanocoatings containing ginger and thyme EOs.

Biofilm-Resistant Nanocoatings Based on ZnO Nanoparticles and Linalool.

Biofilms represent an increasing challenge in the medical practice worldwide, imposing a serious threat to public health. As bacterial strains have developed antibiotic resistance, researcher's attention has been extensively focused on developing more efficient antimicrobial strategies. In this context, the present study reports the synthesis, physicochemical characterization, ex vivo biodistribution, and in vitro evaluation of the capacity of nanostructured surfaces based on zinc oxide (ZnO) and biologically active molecules to modulate clinically relevant microbial biofilms. ZnO nanoparticles (NPs) were synthesized through a co-precipitation method without thermal treatment. The matrix-assisted pulsed laser evaporation (MAPLE) was applied for preparing nanostructured coatings based on ZnO NPs surface modified with linalool that were further characterized by X-ray diffraction (XRD), thermogravimetric analysis with differential scanning calorimetry (TGA-DSC), scanning electron microscopy (SEM), transmission electron microscopy with selected area electron diffraction (TEM-SAED), Fourier-transform infrared spectroscopy (FT-IR), and infrared microscopy (IRM). Histological analyses carried out at 7 days and 14 days after the intraperitoneal administration of linalool modified ZnO NPs revealed the absence of the latter from the brain, kidney, liver, lung, myocardium, and pancreas. Through in vitro assays on prokaryotic cells, it was proven that ZnO coatings hinder microbial biofilm formation of both Gram-positive and Gram-negative bacteria strains.

Anti-Cancer Nanopowders and MAPLE-Fabricated Thin Films Based on SPIONs Surface Modified with Paclitaxel Loaded ß-Cyclodextrin.

Globally, cancer is the second most common cause of death, and Europe accounts for almost 25% of the global cancer burden, although its people make up only 10% of the world's population. Conventional systemically administered anti-cancer drugs come with important drawbacks such as inefficiency due to poor bioavailability and improper biodistribution, severe side effects associated with low therapeutic indices, and the development of multidrug resistance. Therefore, smart nano-engineered targeted drug-delivery systems with tailored pharmacokinetics and biodistribution which can selectively deliver anti-cancer agents directly to the tumor site are the solution to most difficulties encountered with conventional therapeutic tools. Here, we report on the synthesis, physicochemical characterization, and in vitro evaluation of biocompatibility and anti-tumor activity of novel magnetically targetable SPIONs based on magnetite (Fe3O4) nanoparticles' surface modified with ß-cyclodextrin (CD) and paclitaxel (PTX)-guest-host inclusion complexes (Fe3O4@ß-CD/PTX). Both pristine Fe3O4@ß-CD nanopowders and PTX-loaded thin films fabricated by MAPLE technique were investigated. Pristine Fe3O4@ß-CD and Fe3O4@ß-CD/PTX thin films were physicochemically characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermal analysis, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The biocompatibility of bare magnetic nanocomposite thin films was evaluated by MTT cell viability assay on a normal 3T3 osteoblast cell line culture and by measuring the level of NO in the culture medium. No significant modifications, neither in cell viability nor in NO level, could be observed, thereby demonstrating the excellent biocompatibility of the SPIONs thin films. Inverted phase-contrast microscopy showed no evident adverse effect on the morphology of normal osteoblasts. On the other hand, Fe3O4@ß-CD/PTX films decreased the cell viability of the MG-63 osteosarcoma cell line by 85%, demonstrating excellent anti-tumor activity. The obtained results recommend these magnetic hybrid films as promising candidates for future delivery, and hyperthermia applications in cancer treatment.

Recent Advances in Surface Nanoengineering for Biofilm Prevention and Control. Part II: Active, Combined Active and Passive, and Smart Bacteria-Responsive Antibiofilm Nanocoatings.

The second part of our review describing new achievements in the field of biofilm prevention and control, begins with a discussion of the active antibiofilm nanocoatings. We present the antibiofilm strategies based on antimicrobial agents that kill pathogens, inhibit their growth, or disrupt the molecular mechanisms of biofilm-associated increase in resistance and tolerance. These agents of various chemical structures act through a plethora of mechanisms targeting vital bacterial metabolic pathways or cellular structures like cell walls and cell membranes or interfering with the processes that underlie different stages of the biofilm life cycle. We illustrate the latter action mechanisms through inhibitors of the quorum sensing signaling pathway, inhibitors of cyclic-di-GMP signaling system, inhibitors of (p)ppGpp regulated stringent response, and disruptors of the biofilm extracellular polymeric substances matrix (EPS). Both main types of active antibiofilm surfaces, namely non-leaching or contact killing systems, which rely on the covalent immobilization of the antimicrobial agent on the surface of the coatings and drug-releasing systems in which the antimicrobial agent is physically entrapped in the bulk of the coatings, are presented, highlighting the advantages of each coating type in terms of antibacterial efficacy, biocompatibility, selective toxicity, as well as drawbacks and limitations. Developments regarding combined strategies that join in a unique platform, both passive and active elements are not omitted. In such platforms with dual functionality, passive and active strategies can be applied either simultaneously or sequentially. We especially emphasize those systems that can be reversely and repeatedly switched between the non-fouling status and the bacterial killing status, thereby allowing several bacteria-killing/surface regeneration cycles to be performed without significant loss of the initial bactericidal activity. Eventually, smart antibiofilm coatings that release their antimicrobial payload on demand, being activated by various triggers such as changes in local pH, temperature, or enzymatic triggers, are presented. Special emphasis is given to the most recent trend in the field of anti-infective surfaces, specifically smart self-defensive surfaces for which activation and switch to the bactericidal status are triggered by the pathogens themselves.

Recent Advances in Surface Nanoengineering for Biofilm Prevention and Control. Part I: Molecular Basis of Biofilm Recalcitrance. Passive Anti-Biofouling Nanocoatings.

Medical device-associated infections are becoming a leading cause of morbidity and mortality worldwide, prompting researchers to find new, more effective ways to control the bacterial colonisation of surfaces and biofilm development. Bacteria in biofilms exhibit a set of "emergent properties", meaning those properties that are not predictable from the study of free-living bacterial cells. The social coordinated behaviour in the biofilm lifestyle involves intricate signaling pathways and molecular mechanisms underlying the gain in resistance and tolerance (recalcitrance) towards antimicrobial agents as compared to free-floating bacteria. Nanotechnology provides powerful tools to disrupt the processes responsible for recalcitrance development in all stages of the biofilm life cycle. The present paper is a state-of-the-art review of the surface nanoengineering strategies currently used to design antibiofilm coatings. The review is structurally organised in two parts according to the targeted biofilm life cycle stages and molecular mechanisms intervening in recalcitrance development. Therefore, in the present first part, we begin with a presentation of the current knowledge of the molecular mechanisms responsible for increased recalcitrance that have to be disrupted. Further, we deal with passive surface nanoengineering strategies that aim to prevent bacterial cells from settling onto a biotic or abiotic surface. Both "fouling-resistant" and "fouling release" strategies are addressed as well as their synergic combination in a single unique nanoplatform.

In vitro and in vivo studies of novel fabricated bioactive dressings based on collagen and zinc oxide 3D scaffolds.

The paper reports the synthesis and physico-chemical and biological characterization of novel wound dressings based on collagen and essential oil functionalized ZnO nanoparticles intended to improve the treatment of burns and to reduce the risk for developing wound sepsis in patients with burns or chronic wounds. The prepared wound dressings were physico-chemical characterized by Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). In vitro biocompatibility and cytotoxicity was proved on human fibroblast cells, antimicrobial potential was assessed on Gram positive and Gram negative bacteria models (Staphylococcus aureus and Escherichia coli, respectively), while in vivo studies were performed on a rat burn wound experimental model. Functionalized ZnO nanoparticles (NPs) proved to range 15-20 nm in size and contain about 1% orange essential oil (EO), which was utilized as a natural antimicrobial agent. NPs are grain-shapped and have a low tendency to form aggregates. No toxicity was noticed in vitro, as human fibroblasts maintained a normal growth and their membrane integrity in the presence of EO functionalized NPs. The capacity of the prepared wound dressings to act as implantable bioresorbable scaffolds that accelerates wounds healing along with an excellent biocompatibility, lack of cytotoxicity and a good antibacterial activity, make these materials promising and safe candidates for wound dressing, especially in burn patients.

Smart Triggered Release in Controlled Drug Delivery.

BACKGROUND: Smart triggered release in controlled drug delivery has met an astonishing interest from the scientific community in the past few years due to the obvious medical benefits this type of systems represents. The reduction in toxicity due to a non-systemic administration is not the only reason for this increase, although it is a major reason for concern typically in anti-cancer therapy, but also the fact that some good therapeutic substances cannot be used either due to their high hydrophobicity or due to a very poor absorption at the required site of delivery. OBJECTIVE: This review article aims to highlight the efforts made by the scientific community in order to more efficiently trigger the drug payload at its destination, thus avoiding systemic exposure to the drug's toxic effect. RESULTS: In this review article several types of triggers have been evaluated, pH triggered delivery, thermally triggered delivery, REDOX change triggered delivery, as well as modifications made to trigger at a specific location based on the affinity of the receptors for a certain chemical moiety, such as folic acid. CONCLUSIONS: Through a proper nano-formulation the obstacles encountered by systemic delivery strategies can be circumvented, and through minor modifications hydrophobic drugs can be delivered through minor modifications to their structure, ensuring in the meantime that the therapeutic form is broken down by the human body's own internal systems. The main advantages in triggered drug delivery are the better healthcare strategy and the topical delivery, the main person winning in this case being the patient, the one person that should always be at the heart of the medical system.

Bioactive mesoporous silica nanostructures with anti-microbial and anti-biofilm properties.

The increasing rate of antibiotic resistant bacteria associated with nosocomial infections in severely ill patients has urged the need for new antibacterial therapies. Nanostructured materials represent emerging innovative approaches to controlled delivery of different antimicrobial drugs. Delivery systems encapsulating natural compounds with antibacterial effects, such as essential oils have shown a great potential. Herein we report the development of SiO2 mesoporous nanosystems loaded with eucalyptus (EUC), orange (ORA), and cinnamon (CIN) essential oils. These systems were characterized with respect to morphology (using scanning electron microscopy, SEM, and transmission electron microscopy, TEM), porosity (by BET and TEM analysis), chemical composition (by X-ray diffraction, XRD, and Fourier transform infrared spectrometry, FTIR) and loading capacity (by thermogravimetric analysis, TGA). The anti-bacterial and anti-adherence effects were tested against clinically relevant microbial species (Staphylococcus aureus ATCC 25923; Escherichia coli ATCC 25922; and Candida albicans ATCC 10231), while the biocompatibility was evaluated by in vitro tests with L929 mouse fibroblast cells.

Biocompatible hybrid silica nanobiocomposites for the efficient delivery of anti-staphylococcal drugs.

This work reports the non-surfactant templated synthesis and characterization of a new tyrosine-silica/antibiotics (TyR-SiO2/ATBs) nanocomposite, as well as both in vitro and in vivo cytotoxicity and antimicrobial activity against the microbial pathogen Staphylococcus aureus. The in vitro microbiological tests proved that the obtained nanobiostructure significantly enhance the antimicrobial activity of three commonly used antibiotics against S. aureus (i.e. erythromycin (ERI), gentamicin (GEN), and cloxacillin (CLO)) as revealed by the increased diameters of the growth inhibition zones and the decreased minimal inhibitory concentration values, as well as by the inhibitory effect of sub-lethal antibiotic concentrations on the ability of the respective pathogenic strains to adhere and colonize different substrata. These results, correlated with the lack of toxicity against mesenchymal stem cells along with an appropriate in vivo biodistribution highlight the promising therapeutic potential of this carrier that allows a decrease of the required active doses while significantly lessening the harmful side effects of the medication on the host organism.

Functionalized magnetic nanoparticles for biomedical applications.

Functionalized magnetic nanoparticles followed two main directions in the field of biomedical applications: one direction is as image enhancing agents for magnetic resonance imaging (MRI) and the other is as drugdelivery devices for various biologically-active substances. A third field which just emerges in nanomedicine is the field of the so-called theranostic devices which combines in the same delivery vehicle both the therapeutic agent and the contrast substance. The advantages of using nanoparticles instead of larger carriers for delivery of both drug and image contrast enhancing agents will be highlighted throughout this review article. Despite the ever increasing number of articles reporting both in vitro and in vivo studies carried out on functionalized magnetic nanoparticles and envisaging their potential biomedical applications, only few formulations reached the phase of clinical trials and even fewer became marketed products. The perspectives in the field are open, since new drugs require new delivery devices and possibly new means of functionalization. At the same time, the field of nanomedicine also provides the opportunity to better exploit drugs that are already in clinical use by improving their bioavailability through appropriate nanoformulations.

Smart synthetic polymer nanocarriers for controlled and site-specific drug delivery.

The article is an up-to-date review of the state-of-the art in the challenging field of smart synthetic polymer nanocarriers, presenting the most relevant achievements in the area, with a special emphasis on the outstanding potential of these nanovehicles to be used as multifunctional devices capable to deliver their cargo to a specific targeted area in the human body and to release it in a well controlled fashion. Stimuli-responsive nano drug delivery systems are presented according to a classification that takes into account the endogenous or exogenous nature of the stimuli. Each category is amply illustrated by carefully selected examples of the most impressive achievements. The endogenous stimuli category is fully described by presentation of pH, redox potential, and enzyme-responsive nanocarriers. From the category of exogenous stimuli-responsive nanomaterials, we focused our attention on temperature, light and magnetic sensitive nanocarriers.

Methods for synthesizing the macromolecular constituents of smart nanosized carriers for controlled drug delivery.

Smart multifunctional polymeric nanocarriers able to respond to physicochemical changes in their environment or to external stimuli represent a new paradigm in the field of pharmaceutical formulations for controlled drug delivery. The introductory part of the present review deals with this new concept and presents the main advantages resulting from the use of such nanovehicles instead of conventional, much larger drug delivery systems. The access to drug nanocarriers based on smart supramolecular polymeric materials is primarily limited by the available polymerization methods capable to produce polymers with low polydispersity index, as well as much more complex macromolecular architectures with strictly controlled chemical composition, such as block copolymers and star or graft polymers or copolymers. This article reviews the state-of-the art in controlled/"living" free radical polymerization techniques as well as ring opening polymerization methods. Nitroxide mediated free radical polymerization (NMP), atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain-transfer polymerization (RAFT), single electron transfer-living radical polymerization (SET-LRP), single electron transfer-nitroxide radical coupling reaction (SET-NRC), cationic ring opening polymerization (CROP), anionic ring opening polymerization (AROP), and metal catalyzed ring opening polymerization are described, highlighting their mechanistic details and their synthetic potential as well as their limitations. The final part of the article is dedicated to a special type of unimolecular, monodisperse nanocarriers - the dendrimers. Both divergent and convergent approaches to dendrimer synthesis are described along with the therapeutic applications taking advantage of the unique branched tree-like globular structure of dendrimers to treat cancer.

Water dispersible cross-linked magnetic chitosan beads for increasing the antimicrobial efficiency of aminoglycoside antibiotics.

The aim of this study was to obtain a nano-active system to improve antibiotic activity of certain drugs by controlling their release. Magnetic composite nanomaterials based on magnetite core and cross-linked chitosan shell were synthesized via the co-precipitation method and characterized by Fourier transform infrared spectroscopy (FT-IR), infrared microscopy (IRM), scanning electron microscopy (SEM), dynamic light scattering (DLS), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The prepared magnetic composite nanomaterials exhibit a significant potentiating effect on the activity of two cationic (kanamycin and neomycin) drugs, reducing the amount of antibiotics necessary for the antimicrobial effect. The increase in the antimicrobial activity was explained by the fact that the obtained nanosystems provide higher surface area to volume ratio, resulting into higher surface charge density thus increasing affinity to microbial cell and also by controlling their release. In addition to the nano-effect, the positive zeta potential of the synthesized magnetite/cross-linked chitosan core/shell magnetic nanoparticles allows for a more favorable interaction with the usually negatively charged cell wall of bacteria. The novelty of the present contribution is just the revealing of this synergistic effect exhibited by the synthesized water dispersible magnetic nanocomposites on the activity of different antibiotics against Gram-positive and Gram-negative bacterial strains. The results obtained in this study recommend these magnetic water dispersible nanocomposite materials for applications in the prevention and treatment of infectious diseases.

Development of amperometric biosensors based on nanostructured tyrosinase-conducting polymer composite electrodes.

Bio-composite coatings consisting of poly(3,4-ethylenedioxythiophene) (PEDOT) and tyrosinase (Ty) were successfully electrodeposited on conventional size gold (Au) disk electrodes and microelectrode arrays using sinusoidal voltages. Electrochemical polymerization of the corresponding monomer was carried out in the presence of various Ty amounts in aqueous buffered solutions. The bio-composite coatings prepared using sinusoidal voltages and potentiostatic electrodeposition methods were compared in terms of morphology, electrochemical properties, and biocatalytic activity towards various analytes. The amperometric biosensors were tested in dopamine (DA) and catechol (CT) electroanalysis in aqueous buffered solutions. The analytical performance of the developed biosensors was investigated in terms of linear response range, detection limit, sensitivity, and repeatability. A semi-quantitative multi-analyte procedure for simultaneous determination of DA and CT was developed. The amperometric biosensor prepared using sinusoidal voltages showed much better analytical performance. The Au disk biosensor obtained by 50 mV alternating voltage amplitude displayed a linear response for DA concentrations ranging from 10 to 300 µM, with a detection limit of 4.18 µM.

Fabrication, characterization and in vitro profile based interaction with eukaryotic and prokaryotic cells of alginate-chitosan-silica biocomposite.

This work is focused on the fabrication of a new drug delivery system based on polyanionic matrix (e.g. sodium alginate), polycationic matrix (e.g. chitosan) and silica network. The FT-IR, SEM, DTA-TG, eukaryotic cell cycle and viability, and in vitro assay of the influence of the biocomposite on the efficacy of antibiotic drugs were investigated. The obtained results demonstrated the biocompatibility and the ability of the fabricated biocomposite to maintain or improve the efficacy of the following antibiotics: piperacillin-tazobactam, cefepime, piperacillin, imipenem, gentamicin, ceftazidime against Pseudomonas aeruginosa ATCC 27853 and cefazolin, cefaclor, cefuroxime, ceftriaxone, cefoxitin, trimethoprim/sulfamethoxazole against Escherichia coli ATCC 25922 reference strains.