Microspheres based on mannosylated lysine-co-sodium alginate for macrophage-specific delivery of isoniazid

Carbohydrate-based nanocarriers and their application to target macrophages and deliver antimicrobial agents

Many deadly infections are produced by microorganisms capable of sustained survival in macrophages. This reduces exposure to chemadrotherapy, prevents immune detection, and is akin to criminals hiding in police stations. Therefore, the use of glyco-nanoparticles (GNPs) as carriers of therapeutic agents is a burgeoning field. Such an approach can enhance the penetration of drugs into macrophages with specific carbohydrate targeting molecules on the nanocarrier to interact with macrophage lectins. Carbohydrates are natural biological molecules and the key constituents in a large variety of biological events such as cellular communication, infection, inflammation, enzyme trafficking, cellular migration, cancer metastasis and immune functions. The prominent characteristics of carbohydrates including biodegradability, biocompatibility, hydrophilicity and the highly specific interaction of targeting cell-surface receptors support their potential application to drug delivery systems (DDS). This review presents the 21^st century development of carbohydrate-based nanocarriers for drug targeting of therapeutic agents for diseases localized in macrophages. The significance of natural carbohydrate-derived nanoparticles (GNPs) as anti-microbial drug carriers is highlighted in several areas of treatment including tuberculosis, salmonellosis, leishmaniasis, candidiasis, and HIV/AIDS.

Paclitaxel Encapsulation into Dual-Functionalized Multi-Walled Carbon Nanotubes

This work reports the synthesis of multi-walled carbon nanotubes (CNTs) from xylene/ferrocene using catalytic chemical vapor deposition technique. Following characterization using transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), and Raman spectroscopy, CNT surface was dual-functionalized using ethylenediamine and phenylboronic acid groups. Average diameter of CNTs was calculated to be 16.5 nm. EDX spectra confirmed the existence of carbonaceous deposits on the tube's surface. Scattered electron diffraction and X-ray peak broadening calculations showed consistent inter-planer distance of the grown CNTs. Chemical functionalization, confirmed from FT-IR and Raman spectra, showed an enhanced dispersibility of CNTs in water. We describe the changes in the first- and second-order regions of the Raman spectra following the encapsulation of an anti-cancer drug, paclitaxel (PLX), into the free volume of functionalized CNTs. High PLX loading, achieved through its non-covalent π-π stacking within the CNT interior, is confirmed through the blue-shifted, softened G band in the Raman spectrum. While not addressed here, we will exploit this dual functionalization tactic to elaborate the relative role of attached moieties in the affinity interaction of CNTs with extra-cellular sialic acid, a biological target showing metastatic stage-dependent over-expression in colon cancer cells.

Exploring inhalable polymeric dry powders for anti-tuberculosis drug delivery

The growing interest on polymeric delivery systems for pulmonary administration of drugs anticipates a more direct and efficient treatment of diseases such as tuberculosis (TB) that uses the pulmonary route as the natural route of infection. Polymeric microparticles or nano-in-microparticles offer target delivery of drugs to the lungs and the potential to control and sustain drug release within TB infected macrophages improving the efficiency of the anti-TB treatment and reducing side effects. In a dry powder form these inhalable delivery systems have increased stability and prolonged storage time without requiring refrigeration, besides being cost-effective and patient convenient. Thus, this review aims to compile the recent innovations of inhalable polymeric dry powder systems for the delivery of anti-TB drugs exploring the methods of production, aerodynamic characterization and the efficacy of targeted drug delivery systems using in vitro and in vivo models of the disease. Advanced knowledge and promising outcomes of these systems are anticipated to simplify and revolutionize the pulmonary drug delivery and to contribute towards more effective anti-TB treatments.

Nano- and micro-based inhaled drug delivery systems for targeting alveolar macrophages

INTRODUCTION

Macrophages are the most versatile cells in the hematopoietic system and are strategically distributed in tissues to fight pathogens or other foreign particles. In the lung, however, for intracellular infections such as tuberculosis, pneumonia and aspergillosis, bacteria and fungi utilize the alveolar macrophage as a breeding ground. This has become a challenge for the treatment of these infections, as most drugs do not effectively reach the macrophages at therapeutic levels. Alveolar macrophages also play an important role to initiative adaptive immunity toward combating inflammation and cancer in the lung.

AREAS COVERED

This review focuses on the development of micro- and nanotechnology-based drug delivery systems to target alveolar macrophages in association with intracellular infections, cancer and lung inflammation. Aspects of nanoparticle and micron-sized particle engineering through exploitation of particles' physicochemical characteristics such as particle size, surface charge and geometry of particles are discussed. In addition, the application of nanocarriers such as liposomes, polymeric nanoparticles and dendrimers are covered with respect to macrophage targeting.

EXPERT OPINION

Drug delivery targeted to alveolar macrophages in the lung is becoming a reality thanks to micro- and nanotechnology breakthrough. The literature review shows that regulation of physicochemical parameters of particles could be a recipe to enhance macrophage targeting and uptake. However, there is still a need to identify more target-specific receptors in order to facilitate drug targeting. Besides that, the toxicity of nanocarriers arising from prolonged residence in the lung should be taken into consideration during formulation.

Characterization and evaluation of amphotericin B loaded MDP conjugated poly(propylene imine) dendrimers

This paper describes a novel strategy for targeted delivery of amphotericin B (AmB) to macrophages with muramyl dipeptide (MDP) conjugated multimeric poly(propyleneimine) (PPI) dendrimers. Synergistic antiparasitic activity due to immunostimulation by multimeric presentation of MDP on dendrimers was anticipated. MDP conjugated 5.0G PPI (MdPPI) dendrimers were synthesized and characterized. Therapeutic activity and toxicity of dendrimeric formulation of AmB (MdPPIA) were compared with marketed formulations of AmB. Highly significant (P<0.01) reduction in toxicity was observed in hemolytic toxicity and cytotoxicity studies in erythrocytes and J774A.1 macrophage cells, respectively. Formulation MdPPIA showed appreciable macrophage targeting potential and higher or equivalent antiparasitic activity against parasite infected macrophage cell lines and in vivo infection in Balb/c mice. These results suggest the developed MDP conjugated dendrimeric formulation of AmB as a promising immunostimulant targeted drug delivery system and a safer alternative to marketed formulations. From the clinical editor: Parasitic infections remain a significant issue in the clinical setting. The authors in this article studied the use of ligand anchored dendrimeric formulation of Amphotericin B to target infected macrophages and showed reduced toxicity, high anti-leishmanial activity. This may add another treatment option to available formulations in the future.