Aerosolized antimicrobial agents based on degradable dextran nanoparticles loaded with silver carbene complexes

Metal complexes of backbone-halogenated imidazol-2-ylidenes

In this manuscript, literature reports on mono- and di-halogen (F, Cl, Br, and I) substituted at positions 4 or/and 4,5 imidazol-2-ylidene (NHC) metal complexes are discussed: particularly, their structural diversity with various metals (groups 6-13), important physicochemical properties, catalytic and medicinal/biological applications are reviewed. To our knowledge, there are no literature reports on group 4 and 5 metal complexes with this type of NHC ligands. Halogenated imidazol-2-ylidene metal complexes deserve special attention because halogens are the classic electron donating groups (mesomerically) in conjugated aromatic/heteroaromatic ring systems, but electron withdrawing inductively. However, they exhibit a significant electron withdrawing inductive effect, thus providing unique electronic properties. This is important for fine tuning of σ-donor abilities of the "carbenic" carbon of imidazol-2-ylidenes, which directly affect catalytic performance of their metal complexes. Other applications, advantages, and disadvantages of halogenated vs. unsubstituted imidazol-2-ylidene metal complexes are critically analyzed and summarized in this review.

Structure-Activity Relationships in NHC-Silver Complexes as Antimicrobial Agents

Silver has a long history of antimicrobial activity and received an increasing interest in last decades owing to the rise in antimicrobial resistance. The major drawback is the limited duration of its antimicrobial activity. The broad-spectrum silver containing antimicrobial agents are well represented by N-heterocyclic carbenes (NHCs) silver complexes. Due to their stability, this class of complexes can release the active Ag⁺ cations in prolonged time. Moreover, the properties of NHC can be tuned introducing alkyl moieties on N-heterocycle to provide a range of versatile structures with different stability and lipophilicity. This review presents designed Ag complexes and their biological activity against Gram-positive, Gram-negative bacteria and fungal strains. In particular, the structure-activity relationships underlining the major requirements to increase the capability to induce microorganism death are highlighted here. Moreover, some examples of encapsulation of silver-NHC complexes in polymer-based supramolecular aggregates are reported. The targeted delivery of silver complexes to the infected sites will be the most promising goal for the future.

Tumor Microenvironment-Based Stimuli-Responsive Nanoparticles for Controlled Release of Drugs in Cancer Therapy

With the development of nanomedicine technology, stimuli-responsive nanocarriers play an increasingly important role in antitumor therapy. Compared with the normal physiological environment, the tumor microenvironment (TME) possesses several unique properties, including acidity, high glutathione (GSH) concentration, hypoxia, over-expressed enzymes and excessive reactive oxygen species (ROS), which are closely related to the occurrence and development of tumors. However, on the other hand, these properties could also be harnessed for smart drug delivery systems to release drugs specifically in tumor tissues. Stimuli-responsive nanoparticles (srNPs) can maintain stability at physiological conditions, while they could be triggered rapidly to release drugs by specific stimuli to prolong blood circulation and enhance cancer cellular uptake, thus achieving excellent therapeutic performance and improved biosafety. This review focuses on the design of srNPs based on several stimuli in the TME for the delivery of antitumor drugs. In addition, the challenges and prospects for the development of srNPs are discussed, which can possibly inspire researchers to develop srNPs for clinical applications in the future.

Polysaccharide-based formulations as potential carriers for pulmonary delivery - A review of their properties and fates

Polysaccharides can be elite carriers for therapeutic molecules due to their versatility and low probability to trigger toxicity and immunogenic responses. Local and systemic therapies can be achieved through particle pulmonary delivery, a promising non-invasive alternative. Successful pulmonary delivery requires particles with appropriate flowability to reach alveoli and avoid premature clearance mechanisms. Polysaccharides can form micro-, nano-in-micro-, and large porous particles, aerogels, and hydrogels. Herein, the characteristics of polysaccharides used in drug formulations for pulmonary delivery are reviewed, providing insights into structure-function relationships. Charged polysaccharides can confer mucoadhesion, whereas the ability for specific sugar recognition may confer targeting capacity for alveolar macrophages. The method of particle preparation must be chosen considering the properties of the components and the delivery device to be utilized. The fate of polysaccharide-based carriers is dependent on enzyme-triggered hydrolytic and/or oxidative mechanisms, allowing their complete degradation and elimination through urine or reutilization of released monosaccharides.

Pegylated-polycaprolactone nano-sized drug delivery platforms loaded with biocompatible silver(I) complexes for anticancer therapeutics

Cytotoxic potential of Ag(I) coordination compounds against cancer cells is widely recognized, but their frequently low water solubility and potential adverse interactions of Ag(I) ions in biological media require their...

Piperine-Loaded Glycyrrhizic Acid- and PLGA-Based Nanoparticles Modified with Transferrin for Antitumor : Piperine-Loaded Glycyrrhizic Acid- and PLGA-Based Nanoparticles

The purpose of this study was to enhance the antitumor effect of piperine by constructing the nanoparticles modified with transferrin (Tf-PIP-NPs) and evaluating their efficacy in vitro and in vivo. The Tf-PIP-NPs were prepared by the solvent evaporation method, and their properties were characterized. The effects of Tf-PIP-NPs on cytotoxicity, cell uptake, apoptosis, and mitochondrial membrane potential were evaluated in HepG2 cells, MDA-MB-231 cells, and 4T1 cells. In a 4T1 tumor-bearing mouse model, the antitumor efficacy of Tf-PIP-NPs was assessed in terms of tumor volumes, changes in body weight, HE staining, and immunohistochemical analysis. With a mean particle size of 112.2 ± 1.27 nm, the zeta potential of (- 28.0 ± 1.6 mV) Tf-PIP-NPs were rapidly internalized by tumor cells after 1 h through the transferrin receptor (TfR)-mediated endocytosis pathway, significantly inducing cellular apoptosis and mitochondrial membrane potential loss. Although Tf-PIP-NPs had no significant difference with PIP-NPs in tumor volume inhibition due to the presence of tumor microenvironment, it could significantly upregulate the expression of related pro-apoptotic proteins and induce tumor necrosis. We used the self-assembly properties of glycyrrhizic acid (GL) and polymer-PLGA to encapsulate piperine and modified with the transferrin, which provided a promising approach to improve the antitumor efficacy for anticarcinogen.

Internal and External Influences on Stability and Ligand Exchange Reactions in Bromido[3-ethyl-4-aryl-5-(2-methoxypyridin-5-yl)-1-propyl-1,3-dihydro-2H-imidazol-2-ylidene]gold(I) Complexes

The ligand scrambling reaction of gold(I) complexes is a phenomenon occurring primarily in L–Au^I–X (L = phosphine, N-heterocyclic carbene (NHC), and thiol; X = halide and thiol) complexes and has been observed among others for e.g., the bromido[3-ethyl-4-(4-methoxyphenyl)-5-(2-methoxypyridin-5-yl)-1-propyl-1,3-dihydro-2H-imidazol-2-ylidene]gold(I) complex (7a), which underwent ligand rearrangement in aqueous solutions. In this study, we investigated the influence of substituents on the 4-aryl ring of the related (NHC)Au^IBr complexes (1a–9a) in terms of the conversion to the [(NHC)₂Au^I]⁺ (1b–9b) and [(NHC)₂Au^IIIBr₂]⁺ (1c–9c) species. Furthermore, the influence of external factors such as solvent, temperature, concentration, and presence of halides (Cl^–, Br^–, and I^–) or hydroxyl ions was studied to gain a deeper understanding of the ligand rearrangement reaction. The substituent on the 4-aryl ring has a marginal impact on the scrambling reaction. Out of the investigated organic solvents (dimethylformamide (DMF), dimethyl sulfoxide (DMSO), ethanol (EtOH), methanol (MeOH), and acetonitrile (ACN)), only ACN separates single complex molecules. In all other solvents, relatively stable ((NHC)Au^IBr)₂ dimers are present. The addition of water to ACN solutions forces the formation of such dimeric units, starting the transformation to [(NHC)₂Au^I]⁺ and [(NHC)₂Au^IIIBr₂]⁺. The rate-determining step is the release of Br^– from a T-shape intermediate because an excess of KBr terminates this reaction. Furthermore, it is obvious that only single molecules react with halides. The aurophilic interactions between two (NHC)Au^IBr molecules are too strong in the presence of water and largely impeded reaction with halides. As a single molecule, the reaction with Cl^– (e.g., in a 0.9% NaCl solution) is notable, while I^– even leads to a fast and quantitative conversion to (NHC)Au^II and finally to [(NHC)₂Au^I]⁺.

Internal and external factors of the ligand scrambling reaction in (NHC)Au^IBr complexes were investigated by the means of HPLC. The data represent the impact of substituents, temperature, solvent, concentration and addition of halides on the conversion to the respective [(NHC)₂Au^I]⁺ and the oxidation to the [(NHC)₂Au^IIIBr₂]⁺ complexes.

Polysaccharide nanoparticles: from fabrication to applications

The present review highlights the developments in polysaccharide nanoparticles with a particular focus on applications in biomedicine, cosmetics and food.

Enhancing the Anticancer Activity and Selectivity of Goniothalamin Using pH-Sensitive Acetalated Dextran (Ac-Dex) Nanoparticles: A Promising Platform for Delivery of Natural Compounds

Goniothalamin (GTN), a natural compound isolated from Goniothalamus species, has previously demonstrated cytotoxic activity against several cancer cell lines. However, similarly to many natural and synthetic anticancer compounds, GTN presents toxicity toward some healthy cells and low aqueous solubility, decreasing its bioavailability and precluding its application as an antineoplastic drug. In our efforts to improve the pharmacokinetic behavior and selectivity of GTN against cancer cells, we developed a polymeric nanosystem, in which rac-GTN was encapsulated in pH-responsive acetalated dextran (Ac-Dex) nanoparticles (NPs) with high loadings of the bioactive compound. Dynamic light scattering (DLS) analysis showed that the nanoparticles obtained presented a narrow size distribution of around 100 nm in diameter, whereas electron microscopy (EM) images showed nanoparticles with a regular spherical morphology in agreement with the size range obtained by DLS. Stability and release studies indicated that the GTN@Ac-Dex NPs presented high stability under physiological conditions (pH 7.4) and disassembled under slightly acidic conditions (pH 5.5), releasing the rac-GTN in a sustained manner. In vitro assays showed that GTN@Ac-Dex NPs significantly increased cytotoxicity and selectivity against cancer cells when compared with the empty Ac-Dex NPs and the free rac-GNT. Cellular uptake and morphology studies using MCF-7 cells demonstrated that GTN@Ac-Dex NPs are rapidly internalized into the cancer cells, causing cell death. In vivo investigation confirmed the efficient release of rac-GTN from GTN@Ac-Dex NPs, resulting in the delay of prostate cancer progression in transgenic adenocarcinoma of the mouse prostate (TRAMP) model. Furthermore, liver histopathology evaluation after treatment with GTN@Ac-Dex NPs showed no evidence of toxicity. Therefore, the in vitro and in vivo findings suggest that the Ac-Dex NPs are a promising nanosystem for the sustained delivery of rac-GTN into tumors.

Receptor-mediated Uptake of Folic Acid-functionalized Dextran Nanoparticles for Applications in Photodynamic Therapy

In photodynamic therapy (PDT), photosensitizers and light are used to cause photochemically induced cell death. The selectivity and the effectiveness of the phototoxicity in cancer can be increased by a specific uptake of the photosensitizer into tumor cells. A promising target for this goal is the folic acid receptor α (FRα), which is overexpressed on the surface of many tumor cells and mediates an endocytotic uptake. Here, we describe a polysaccharide-based nanoparticle system suitable for targeted uptake and its photochemical and photobiological characterization. The photosensitizer 5, 10, 15, 20-tetraphenyl-21H, 23H-porphyrine (TPP) was encapsulated in spermine- and acetal-modified dextran (SpAcDex) nanoparticles and conjugated with folic acid (FA) on the surface [SpAcDex(TPP)-FA]. The particles are successfully taken up by human HeLa-KB cells, and a light-induced cytotoxicity is observable. An excess of free folate as the competitor for the FRα-mediated uptake inhibits the phototoxicity. In conclusion, folate-modified SpAcDex particles are a promising drug delivery system for a tumor cell targeted photodynamic therapy.

Biodegradable and pH-Responsive Acetalated Dextran (Ac-Dex) Nanoparticles for NIR Imaging and Controlled Delivery of a Platinum-Based Prodrug into Cancer Cells

Nanoparticles (NPs) based on the biodegradable acetalated dextran polymer (Ac-Dex) were used for near-infrared (NIR) imaging and controlled delivery of a Pt^IV prodrug into cancer cells. The Ac-Dex NPs loaded with the hydrophobic Pt^IV prodrug 3 (Pt^IV/Ac-Dex NPs) and with the novel hydrophobic NIR-fluorescent dye 9 (NIR-dye 9/Ac-Dex NPs), as well as Ac-Dex NPs coloaded with both compounds (coloaded Ac-Dex NPs), were assembled using a single oil-in-water nanoemulsion method. Dynamic light scattering measurements and scanning electron microscopy images showed that the resulting Ac-Dex NPs are spherical with an average diameter of 100 nm, which is suitable for accumulation in tumors via the enhanced permeation and retention effect. The new nanosystems exhibited high drug-loading capability, high encapsulation efficiency, high stability in physiological conditions, and pH responsiveness. Drug-release studies clearly showed that the Pt^IV prodrug 3 release from Ac-Dex NPs was negligible at pH 7.4, whereas at pH 5.5, this compound was completely released with a controlled rate. Confocal laser scanning microscopy unambiguously showed that the NIR-dye 9/Ac-Dex NPs were efficiently taken up by MCF-7 cells, and cytotoxicity assays against several cell lines showed no significant toxicity of blank Ac-Dex NPs up to 1 mg mL^-1. The IC₅₀ values obtained for the Pt^IV prodrug encapsulated in Ac-Dex NPs were much lower when compared with the IC₅₀ values obtained for the free Pt^IV complex and cisplatin in all cell lines tested. Overall, our results demonstrate, for the first time, that Ac-Dex NPs constitute a promising drug delivery platform for cancer therapy.

Disease-Triggered Drug Release Effectively Prevents Acute Inflammatory Flare-Ups, Achieving Reduced Dosing

For conditions with inflammatory flare-ups, fast drug-release from a depot is crucial to reduce cell infiltration and prevent long-term tissue destruction. While this concept has been explored for chronic diseases, preventing acute inflammatory flares has not been explored. To address this issue, a preventative inflammation-sensitive system is developed and applied to acute gout, a condition where millions of inflammatory cells are recruited rapidly, causing excruciating and debilitating pain. Rapid drug release is first demonstrated from a pH-responsive acetalated dextran particle loaded with dexamethasone (AcDex-DXM), reducing proinflammatory cytokines in vitro as efficiently as free drug. Then, using the air pouch model of gout, mice are pretreated 24 h before inducing inflammation. AcDex-DXM reduces overall cell infiltration with decreased neutrophils, increases monocytes, and diminishes cytokines and chemokines. In a more extended prophylaxis model, murine joints are pretreated eight days before initiating inflammation. After quantifying cell infiltration, only AcDex-DXM reduces the overall joint inflammation, where neither free drug nor a conventional drug-depot achieves adequate anti-inflammatory effects. Here, the superior efficacy of disease-triggered drug-delivery to prevent acute inflammation is demonstrated over free drug and slow-release depots. This approach and results promise exciting treatment opportunities for multiple inflammatory conditions suffering from acute flares.

Soft Nanohydrogels Based on Laponite Nanodiscs: A Versatile Drug Delivery Platform for Theranostics and Drug Cocktails

A new nanohydrogel drug delivery platform based on Laponite nanodiscs, polyacrylate, and sodium phosphate salts is described. The hybrid nanohydrogel is tailored to obtain soft and flexible nanohydrogels with G' around 3 kPa, which has been proposed as the ideal stiffness for drug delivery applications. In vitro studies demonstrate that the new nanohydrogels are biocompatible, biodegradable, nonswellable, pH-responsive, and noncytotoxic and are able to deliver antineoplastic drugs into cancer cells. The IC₅₀ of nanohydrogels containing cisplatin, 4-fluorouracil, and cyclophosphamide is significantly lower than the IC₅₀ of the free drugs. In vivo experiments suggest that the new nanomaterials are biocompatible and do not accumulate in crucial organs. The simple formulation procedure enables encapsulation of virtually any water-soluble molecule, without the need for chemical modification of the guests. These nanohydrogels are a versatile platform that enables the simultaneous encapsulation of several cancer drugs, yielding an efficient drug cocktail delivery system, which for instance presents a positive synergistic effect against MCF-7 cells.

Colloid particle formulations for antimicrobial applications

Colloidal particles are being extensively studied in various antimicrobial applications due to their small size to volume ratio and ability to exhibit a wide spectrum of antibacterial, antifungal, antialgal and antiviral action. The present review focuses on various nanoparticles (NPs) of inorganic, organic and hybrid materials, and discusses some of the methods for their preparation as well as mechanisms of their antimicrobial action. We consider the antimicrobial applications of metal oxide nanoparticles (ZnO, MgO, CuO, Cu₂O, Al₂O₃, TiO₂, CeO₂ and Y₂O₃), metal nanoparticles (NPs), such as copper, silver and gold, metal hydroxide NPs such as Mg(OH)₂ as well as hybrid NPs made from biodegradable materials, such as chitosan, lignin and dextran, loaded with other antimicrobial agents. Recent developments for targeted delivery of antimicrobials by using colloid antibodies for microbial cell shape and surface recognition are also discussed. We also consider recent advances in the functionalization of nanoparticles and their potential antimicrobial applications as a viable alternative of conventional antibiotics and antiseptic agents which can help to tackle antimicrobial resistance. The review also covers the recently developed environmentally benign NPs (EbNPs) as a "safer-by-design" green chemistry solution of the post use fate of antimicrobial nanomaterials.

Synthesis, characterization, in vitro SAR and in vivo evaluation of N,N'bisnaphthylmethyl 2-alkyl substituted imidazolium salts against NSCLC

Alkyl- and N,N'-bisnaphthyl-substituted imidazolium salts were tested in vitro for their anti-cancer activity against four non-small cell lung cancer cell lines (NCI-H460, NCI-H1975, HCC827, A549). All compounds had potent anticancer activity with 2 having IC50 values in the nanomolar range for three of the four cell lines, a 17-fold increase in activity against NCI-H1975 cells when compared to cisplatin. Compounds 1-4 also showed high anti-cancer activity against nine NSCLC cell lines in the NCI-60 human tumor cell line screen. In vitro studies performed using the Annexin V and JC-1 assays suggested that NCI-H460 cells treated with 2 undergo an apoptotic cell death pathway and that mitochondria could be the cellular target of 2 with the mechanism of action possibly related to a disruption of the mitochondrial membrane potential. The water solubilities of 1-4 was over 4.4mg/mL using 2-hydroxypropyl-β-cyclodextrin as a chemical excipient, thereby providing sufficient solubility for systemic administration.

Synthesis, characterization, and in vitro SAR evaluation of N,N'-bis(arylmethyl)-C2-alkyl substituted imidazolium salts

A series of C2-alkyl substituted N,N'-bis(arylmethyl)imidazolium salts were synthesized, characterized, and tested for their in vitro anti-cancer activity against multiple non-small cell lung cancer cell lines by our group and the National Cancer Institute's-60 human tumor cell line screen to establish a structure-activity relationship. Compounds are related to previously published N,N'-bis(arylmethyl)imidazolium salts but utilize the historical quinoline motif and anion effects to increase the aqueous solubility. Multiple derivatives displayed high anti-cancer activity with IC50 values in the nanomolar to low micromolar range against a panel of non-small cell lung cancer cell lines. Several of these derivatives have high aqueous solubilities with potent anti-proliferative properties and are ideal candidates for future in vivo xenograft studies and have high potential to progress into clinic use.

Acetalated Dextran: A Tunable and Acid-Labile Biopolymer with Facile Synthesis and a Range of Applications

Acetalated dextran (Ac-DEX) is a tunable acid-labile biopolymer with facile synthesis, aptly designed for the formulation of microparticles for vaccines and immune modulation. Tunability of degradation is achieved based on the kinetics of reaction and the molecular weight of the parent dextran polymer. This tunability translated to differential rates of activation of CD8+ T cells in an in vitro ovalbumin model and illustrated that acid-labile polymer can activate CD8+ T cells at an increased rate compared to acid-insensitive polymers. In addition, Ac-DEX has been used to encapsulate small molecules, deliver nucleotides, transport inorganic molecules, formulate immune modulating therapies and vaccines, and trigger pH responsive constructs for therapy. Here we highlight the properties and results of Ac-DEX nano-/microparticles as well as the use of the polymer in other constructs and chemistries.

Polymeric nanoparticles in development for treatment of pulmonary infectious diseases

Serious lung infections, such as pneumonia, tuberculosis, and chronic obstructive cystic fibrosis-related bacterial diseases, are increasingly difficult to treat and can be life-threatening. Over the last decades, an array of therapeutics and/or diagnostics have been exploited for management of pulmonary infections, but the advent of drug-resistant bacteria and the adverse conditions experienced upon reaching the lung environment urge the development of more effective delivery vehicles. Nanotechnology is revolutionizing the approach to circumventing these barriers, enabling better management of pulmonary infectious diseases. In particular, polymeric nanoparticle-based therapeutics have emerged as promising candidates, allowing for programmed design of multi-functional nanodevices and, subsequently, improved pharmacokinetics and therapeutic efficiency, as compared to conventional routes of delivery. Direct delivery to the lungs of such nanoparticles, loaded with appropriate antimicrobials and equipped with 'smart' features to overcome various mucosal and cellular barriers, is a promising approach to localize and concentrate therapeutics at the site of infection while minimizing systemic exposure to the therapeutic agents. The present review focuses on recent progress (2005-2015) important for the rational design of nanostructures, particularly polymeric nanoparticles, for the treatment of pulmonary infections with highlights on the influences of size, shape, composition, and surface characteristics of antimicrobial-bearing polymeric nanoparticles on their biodistribution, therapeutic efficacy, and toxicity. WIREs Nanomed Nanobiotechnol 2016, 8:842-871. doi: 10.1002/wnan.1401 For further resources related to this article, please visit the WIREs website.

Dextran-based therapeutic nanoparticles for hepatic drug delivery

AIM

Evaluation of dextran-based nanoparticles (DNP) as a drug delivery system to target myeloid cells of the liver.

MATERIALS & METHODS

DNP were synthesized and optionally PEGylated. Their toxicity and cellular uptake were studied in vitro. Empty and siRNA-carrying DNP were tested in vivo with regard to biodistribution and cellular uptake.

RESULTS

In vitro, DNP were taken up by cells of the myeloid lineage without compromising their viability. In vivo, empty and siRNA-carrying DNP distributed to the liver where a single treatment addressed approximately 70% of macrophages and dendritic cells. Serum parameters indicated no in vivo toxicity.

CONCLUSION

DNP are multifunctional liver-specific drug carriers which lack toxic side effects and may be utilized in clinical applications targeting liver macrophages.

In vitro and in vivo uptake studies of PAMAM G4.5 dendrimers in breast cancer

Background

Breast cancer is the second leading cause of cancer death worldwide. Nanotechnology approaches can overcome the side effects of chemotherapy as well as improve the efficacy of drugs. Dendrimers are nanometric size polymers which are suitable as drug delivery systems. To the best of our knowledge, studies on the application of PAMAM G4.5 (polyamidoamine half generation 4) dendrimers as potential drug delivery systems in breast cancer have not been reported. In this work we developed a PAMAM G4.5 dendrimer containing FITC (fluorescein isothiocyanate) dye to study their uptake by murine breast cancer cells and BALB/c mice breast tumors.

Results

We performed a reaction between FITC and PAMAM G4.5 dendrimers which were previously derivatized with piperazine (linker molecule), characterized them by ¹H NMR (proton nuclear magnetic resonance) spectroscopy and MALDI-TOF (matrix-assisted laser desorption/ionization- time-of-flight) mass spectrometry. The experimental data indicated that 2 FITC molecules could be bound covalently at the PAMAM G4.5 dendrimer surface, with 17 FITC molecules probably occluded in PAMAM dendrimers cavity. PAMAM-FITC dendrimer (PAMAM G4.5-piperazinyl-FITC dendrimer) size distribution was evaluated by DLS (dynamic light scattering) and TEM (transmission electron microscopy). The nanoparticle hydrodynamic size was 96.3 ± 1.4 nm with a PdI (polydispersion index) of 0.0296 ± 0.0171, and the size distribution measured by TEM was 44.2 ± 9.2 nm. PAMAM-FITC dendrimers were neither cytotoxic in 4T1 cells nor hemolytic up to 24 h of incubation. In addition, they were uptaken in vitro by 4T1 cells and in vivo by BALB/c mice breast tumors. PAMAM G4.5-piperazinyl-FITC dendrimer intracellular distribution was observed through histologic analysis of the tumor by laser confocal microscopy.

Conclusion

These results indicate that PAMAM G4.5 dendrimers enter tumor tissue cells, being good candidates to be used as antitumor drug delivery systems for breast cancer treatment and diagnosis.

An update on polysaccharide-based nanomaterials for antimicrobial applications

Scientific community has made a lot of efforts to combat the infectious diseases using antimicrobial agents, but these are associated with problems of development of multi-drug resistance and their adverse side effects. To tackle these challenges, nanocarrier-based drug delivery system using polysaccharides has received enormous attention in the past few years. These antimicrobial agents can become more efficacious when adsorbed, entrapped, or linked to polysaccharides. In addition, these nanocarrier-based systems provide an increase in the surface area of the drug and are able to achieve the targeted drug delivery as well as used for the synthesis of packaging materials with improved mechanical strength, barrier, and antimicrobial properties. This review focuses on potential therapeutic applications of nanocarrier-based drug delivery systems using polysaccharides for antimicrobial applications.

Anti-tumor activity of lipophilic imidazolium salts on select NSCLC cell lines

The anti-tumor activity of imidazolium salts is highly dependent upon the substituents on the nitrogen atoms of the imidazolium cation. We have synthesized and characterized a series of naphthalene-substituted imidazolium salts and tested them against a variety of non-smallcell lung cancer cell lines. Several of these complexes displayed anticancer activity comparable to cisplatin. These compounds induced apoptosis in the NCI-H460 cell line as determined by Annexin V staining, caspase-3, and PARP cleavage. These results strongly suggest that this class of compounds can serve as potent chemotherapeutic agents.

Degradable polyphosphoester-based silver-loaded nanoparticles as therapeutics for bacterial lung infections

In this study, a new type of degradable polyphosphoester-based polymeric nanoparticle, capable of carrying silver cations via interactions with alkyne groups, has been developed as a potentially effective and safe treatment for lung infections. It was found that up to 15% (w/w) silver loading into the nanoparticles could be achieved, consuming most of the pendant alkyne groups along the backbone, as revealed by Raman spectroscopy. The well-defined Ag-loaded nanoparticles released silver in a controlled and sustained manner over 5 days, and displayed enhanced in vitro antibacterial activities against cystic fibrosis-associated pathogens and decreased cytotoxicity to human bronchial epithelial cells, in comparison to silver acetate.

Aspects of pulmonary drug delivery strategies for infections in cystic fibrosis--where do we stand?

INTRODUCTION

Cystic fibrosis (CF) is the most common life-shortening hereditary disease among Caucasians and is associated with severe pulmonary damage because of decreased mucociliary clearance and subsequent chronic bacterial infections. Approximately 90% of CF patients die from lung destruction, promoted by pathogens such as Pseudomonas aeruginosa. Consequently, antibiotic treatment is a cornerstone of CF therapy, preventing chronic infection and reducing bacterial load, exacerbation rates and loss of pulmonary function. Many drugs are administered by inhalation to achieve high pulmonary concentration and to lower systemic side effects. However, pulmonary deposition of inhaled drugs is substantially limited by bronchial obstruction with viscous mucus and restrained by intrapulmonary bacterial biofilms.

AREAS COVERED

This review describes challenges in the therapy of CF-associated infections by inhaled antibiotics and summarizes the current state of microtechnology and nanotechnology-based pulmonary antibiotic delivery strategies. Recent and ongoing clinical trials as well as experimental approaches for microparticle/nanoparticle-based antibiotics are presented and their advantages and disadvantages are discussed.

EXPERT OPINION

Rapidly increasing antimicrobial resistance accompanied by the lack of novel antibiotics force targeted and more efficient use of the available drugs. Encapsulation of antimicrobials in nanoparticles or microparticles of organic polymers may have great potential for use in CF therapy.