Nano into Micro Formulations of Tobramycin for the Treatment of Pseudomonas aeruginosa Infections in Cystic Fibrosis

TAT decorated siRNA polyplexes for inhalation delivery in anti-asthma therapy

In this work, a novel protonable copolymer was designed to deliver siRNA through the inhalation route, as an innovative formulation for the management of asthma. This polycation was synthesized by derivatization of α,β-poly(N-2-hydroxyethyl)D,L-aspartamide (PHEA) first with 1,2-Bis(3-aminopropylamino)ethane (bAPAE) and then with a proper amount of maleimide terminated poly(ethylene glycol) (PEG-MLB), with the aim to increase the superficial hydrophilicity of the system, allowing the diffusion trough the mucus layer. Once the complexation ability of the copolymer has been evaluated, obtaining nanosized polyplexes, polyplexes were functionalized on the surface with a thiolated TAT peptide, a cell-penetrating peptide (CPP), exploiting a thiol-ene reaction. TAT decorated polyplexes result to be highly cytocompatible and able to retain the siRNA with a suitable complexation weight ratio during the diffusion process through the mucus. Despite polyplexes establish weak bonds with the mucin chains, these can diffuse efficiently through the mucin layer and therefore potentially able to reach the bronchial epithelium. Furthermore, through cellular uptake studies, it was possible to observe how the obtained polyplexes penetrate effectively in the cytoplasm of bronchial epithelial cells, where they can reduce IL-8 gene expression, after LPS exposure. In the end, in order to obtain a formulation administrable as an inhalable dry powder, polyplexes were encapsulated in mannitol-based microparticles, by spray freeze drying, obtaining highly porous particles with proper technological characteristics that make them potentially administrable by inhalation route.

Modulation of engineered nanomaterial interactions with organ barriers for enhanced drug transport

The biomedical use of nanoparticles (NPs) has been the focus of intense research for over a decade. As most NPs are explored as carriers to alter the biodistribution, pharmacokinetics and bioavailability of associated drugs, the delivery of these NPs to the tissues of interest remains an important topic. To date, the majority of NP delivery studies have used tumor models as their tool of interest, and the limitations concerning tumor targeting of systemically administered NPs have been well studied. In recent years, the focus has also shifted to other organs, each presenting their own unique delivery challenges to overcome. In this review, we discuss the recent advances in leveraging NPs to overcome four major biological barriers including the lung mucus, the gastrointestinal mucus, the placental barrier, and the blood-brain barrier. We define the specific properties of these biological barriers, discuss the challenges related to NP transport across them, and provide an overview of recent advances in the field. We discuss the strengths and shortcomings of different strategies to facilitate NP transport across the barriers and highlight some key findings that can stimulate further advances in this field.

Codelivery of synergistic antimicrobials with polyelectrolyte nanocomplexes to treat bacterial biofilms and lung infections

Bacterial biofilm infections, particularly those of Pseudomonas aeruginosa (PA), have high rates of antimicrobial tolerance and are commonly found in chronic wound and cystic fibrosis lung infections. Combination therapeutics that act synergistically can overcome antimicrobial tolerance; however, the delivery of multiple therapeutics at relevant dosages remains a challenge. We therefore developed a nanoscale drug carrier for antimicrobial codelivery by combining approaches from polyelectrolyte nanocomplex (NC) formation and layer-by-layer electrostatic self-assembly. This strategy led to NC drug carriers loaded with tobramycin antibiotics and antimicrobial silver nanoparticles (AgTob-NCs). AgTob-NCs displayed synergistic enhancements in antimicrobial activity against both planktonic and biofilm PA cultures, with positively charged NCs outperforming negatively charged formulations. NCs were evaluated in mouse models of lung infection, leading to reduced bacterial burden and improved survival outcomes. This approach therefore shows promise for nanoscale therapeutic codelivery to treat recalcitrant bacterial infections.

Untangling Mucosal Drug Delivery: Engineering, Designing, and Testing Nanoparticles to Overcome the Mucus Barrier

Mucus is a complex viscoelastic gel and acts as a barrier covering much of the soft tissue in the human body. High vascularization and accessibility have motivated drug delivery to various mucosal surfaces; however, these benefits are hindered by the mucus layer. To overcome the mucus barrier, many nanomedicines have been developed, with the goal of improving the efficacy and bioavailability of drug payloads. Two major nanoparticle-based strategies have emerged to facilitate mucosal drug delivery, namely, mucoadhesion and mucopenetration. Generally, mucoadhesive nanoparticles promote interactions with mucus for immobilization and sustained drug release, whereas mucopenetrating nanoparticles diffuse through the mucus and enhance drug uptake. The choice of strategy depends on many factors pertaining to the structural and compositional characteristics of the target mucus and mucosa. While there have been promising results in preclinical studies, mucus-nanoparticle interactions remain poorly understood, thus limiting effective clinical translation. This article reviews nanomedicines designed with mucoadhesive or mucopenetrating properties for mucosal delivery, explores the influence of site-dependent physiological variation among mucosal surfaces on efficacy, transport, and bioavailability, and discusses the techniques and models used to investigate mucus-nanoparticle interactions. The effects of non-homeostatic perturbations on protein corona formation, mucus composition, and nanoparticle performance are discussed in the context of mucosal delivery. The complexity of the mucosal barrier necessitates consideration of the interplay between nanoparticle design, tissue-specific differences in mucus structure and composition, and homeostatic or disease-related changes to the mucus barrier to develop effective nanomedicines for mucosal delivery.

Respirable spray dried vancomycin coated magnetic nanoparticles for localized lung delivery

Bacterial pneumonia is a common pulmonary infection responsible for premature death. Biomaterials based-carriers loaded with antibiotics enhance drug potency through localizing the therapy, minimizing the associated adverse effects, and improving patient compliance. Herein, this study reports the preparation of an inhalable dry powder formulation composed of a nano-in-microparticles. Vancomycin was adsorbed on the core of magnetic nanoparticles followed by spray drying into lactose/dextran to optimize the aerodynamic performance and allow the local delivery of the drug into the bacterial pneumonia infection site. Lactose and Dextran are polysaccharides commonly used for pulmonary delivery due to their optimum aerodynamic performance and biocompatibility. The preparation of the nano-in-micro particles with optimum properties was confirmed using FTIR, TEM, SEM, Laser-diffraction, ICP-AES and TGA. The TEM micrographs confirmed the formation of spherical magnetic nanoparticles with a diameter 14.7 ± 5.9 nm and a coating thickness 3 - 16 nm, while laser diffraction showed that outer microparticles exhibited a mean diameter < 5 µm. The formulations demonstrated a promising activity against S. aureus and MRSA and better biocompatibility using MTT assay. In vivo safety and pharmacokinetic studies confirmed the localization of VAN in lung tissue and minimized adverse effects compared to free VAN. Therefore, the developed nano-in-microparticles confers a good potential for eradication of lung infections.

Nanoparticle-Based Drug Delivery System: The Magic Bullet for the Treatment of Chronic Pulmonary Diseases

Chronic pulmonary diseases encompass different persistent and lethal diseases, including chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), cystic fibrosis (CF), asthma, and lung cancers that affect millions of people globally. Traditional pharmacotherapeutic treatment approaches (i.e., bronchodilators, corticosteroids, chemotherapeutics, peptide-based agents, etc.) are not satisfactory to cure or impede diseases. With the advent of nanotechnology, drug delivery to an intended site is still difficult, but the nanoparticle's physicochemical properties can accomplish targeted therapeutic delivery. Based on their surface, size, density, and physical-chemical properties, nanoparticles have demonstrated enhanced pharmacokinetics of actives, achieving the spotlight in the drug delivery research field. In this review, the authors have highlighted different nanoparticle-based therapeutic delivery approaches to treat chronic pulmonary diseases along with the preparation techniques. The authors have remarked the nanosuspension delivery via nebulization and dry powder carrier is further effective in the lung delivery system since the particles released from these systems are innumerable to composite nanoparticles. The authors have also outlined the inhaled particle's toxicity, patented nanoparticle-based pulmonary formulations, and commercial pulmonary drug delivery devices (PDD) in other sections. Recently advanced formulations employing nanoparticles as therapeutic carriers for the efficient treatment of chronic pulmonary diseases are also canvassed.

Characteristics of SARS-CoV2 that may be useful for nanoparticle pulmonary drug delivery

As a non-invasive method of local and systemic drug delivery, the administration of active pharmaceutical ingredients (APIs) via the pulmonary route represents an ideal approach for the therapeutic treatment of pulmonary diseases. The pulmonary route provides a number of advantages, including the rapid absorption which results from a high level of vascularisation over a large surface area and the successful avoidance of first-pass metabolism. Aerosolization of nanoparticles (NPs) is presently under extensive investigation and exhibits a high potential for targeted delivery of therapeutic agents for the treatment of a wide range of diseases. NPs need to possess specific characteristics to facilitate their transport along the pulmonary tract and appropriately overcome the barriers presented by the pulmonary system. The most challenging aspect of delivering NP-based drugs via the pulmonary route is developing colloidal systems with the optimal physicochemical parameters for inhalation. The physiochemical properties of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) have been investigated as a template for the synthesis of NPs to assist in the formulation of virus-like particles (VLPs) for pharmaceutical delivery, vaccine production and diagnosis assays.

The rough inhalable ciprofloxacin hydrochloride microparticles based on silk fibroin for non-cystic fibrosis bronchiectasis therapy with good biocompatibility

Non-cystic fibrosis bronchiectasis (NCFB) is a chronic respiratory disease, and the thick and viscous mucus covering on respiratory epithelia can entrap the inhaled drugs, resulting in compromised therapeutic efficiency. In order to solve this problem, the inhalable ciprofloxacin hydrochloride microparticles (CMs) based on silk fibroin (SF) and mannitol (MAN) were designed and developed. SF was applied to increase the loading efficiency of ciprofloxacin hydrochloride by strong electrostatic interactions. MAN could facilitate the penetration of drugs through mucus, which ensured the drugs could reach their targets before clearance. Furthermore, the aerodynamic performance of the inhalable microparticles could be tuned by changing the surface roughness to achieve a high fine particle fraction value (45.04%). The antibacterial effects of CMs were also confirmed by measuring the minimum inhibitory concentration against four different bacteria strains. Moreover, a series of experiments both in vitro and in vivo showed that CMs would not affect the lung function and induce the secretion of inflammatory cytokines in lungs, demonstrating their excellent biocompatibility and biosafety. Therefore, CMs might be a promising pulmonary drug delivery system for the treatment of NCFB.

Polymeric nano- and microparticulate drug delivery systems for treatment of biofilms

Now-a-days healthcare systems face great challenges with antibiotic resistance and low efficacy of antibiotics when combating pathogenic bacteria and bacterial biofilms. Administration of an antibiotic in its free form is often ineffective due to lack of selectivity to the infectious site and breakdown of the antibiotic before it exerts its effect. Therefore, polymeric delivery systems, where the antibiotic is encapsulated into a formulation, have shown great promise, facilitating a high local drug concentration at the site of infection, a controlled drug release and less drug degradation. All this leads to improved therapeutic effects and fewer systemic side effects together with a lower risk of developing antibiotic resistance. Here, we review and provide a comprehensive overview of polymer-based nano- and microparticles as carriers for antimicrobial agents and their effect on eradicating bacterial biofilms. We have a main focus on polymeric particulates containing poly(lactic-co-glycolic acid), chitosan and polycaprolactone, but also strategies involving combinations of these polymers are included. Different production techniques are reviewed and important parameters for biofilm treatment are discussed such as drug loading capacity, control of drug release, influence of particle size and mobility in biofilms. Additionally, we reflect on other promising future strategies for combating biofilms such as lipid-polymer hybrid particles, enzymatic biofilm degradation, targeted/triggered antibiotic delivery and future alternatives to the conventional particles.

Approaches for the inhibition and elimination of microbial biofilms using macromolecular agents

Biofilms are complex three-dimensional structures formed at interfaces by the vast majority of bacteria and fungi. These robust communities have an important detrimental impact on a wide range of industries and other facets of our daily lives, yet their removal is challenging owing to the high tolerance of biofilms towards conventional antimicrobial agents. This key issue has driven an urgent search for new innovative antibiofilm materials. Amongst these emerging approaches are highly promising materials that employ aqueous-soluble macromolecules, including peptides, proteins, synthetic polymers, and nanomaterials thereof, which exhibit a range of functionalities that can inhibit biofilm formation or detach and destroy organisms residing within established biofilms. In this Review, we outline the progress made in inhibiting and removing biofilms using macromolecular approaches, including a spotlight on cutting-edge materials that respond to environmental stimuli for "on-demand" antibiofilm activity, as well as synergistic multi-action antibiofilm materials. We also highlight materials that imitate and harness naturally derived species to achieve new and improved biomimetic and biohybrid antibiofilm materials. Finally, we share some speculative insights into possible future directions for this exciting and highly significant field of research.

Enhanced Eradication of Mucin-Embedded Bacterial Biofilm by Locally Delivered Antibiotics in Functionalized Microcontainers

Bacterial biofilm-related infections are difficult to eradicate and require repeated treatments with high doses of antibiotics. Thus, there is an urgent need for new treatment strategies that minimize the use of antibiotics while enhancing biofilm eradication. Functionalized reservoir-based microdevices, such as, microcontainers (MCs), offer, high drug loading capacity, mucus embedment, and tuneable drug release. Here, MCs are loaded with the antibiotic ciprofloxacin (CIP), and sealed with a lid consisting of chitosan (CHI) and a mucolytic agent, N-acetylcysteine (NAC). It is found that CHI and NAC work synergistically, showing improved mucoadhesive and mucolytic properties. To better mimic the in vivo habitat of Pseudomonas aeruginosa (P. aeruginosa), the biofilm is grown in a mucin-containing medium on a newly developed centrifugal microfluidic system. The CHI/NAC coated MCs improve eradication of biofilm (88.22 ± 2.89%) compared to CHI-coated MCs (72.68 ± 3.73%) or bolus injection (39.86 ± 13.28%). The findings suggest that MCs are significantly more efficient than a bolus treatment. Furthermore, CHI/NAC functionalized MCs kill most of the biomass already after 5 h (80.75 ± 3.50%), mainly due to a fast drug release. This is the first time that CHI/NAC has been combined as a coating to explore mucolytic properties on bacterial biofilms.

A pulmonary mucus surrogate for investigating antibiotic permeation and activity against Pseudomonas aeruginosa biofilms

BACKGROUND

Pulmonary infections associated with Pseudomonas aeruginosa can be life-threatening for patients suffering from chronic lung diseases such as cystic fibrosis. In this scenario, the formation of biofilms embedded in a mucus layer can limit the permeation and the activity of anti-infectives.

OBJECTIVES

Native human pulmonary mucus can be isolated from endotracheal tubes, but this source is limited for large-scale testing. This study, therefore, aimed to evaluate a modified artificial sputum medium (ASMmod) with mucus-like viscoelastic properties as a surrogate for testing anti-infectives against P. aeruginosa biofilms.

METHODS

Bacterial growth in conventional broth cultures was compared with that in ASMmod, and PAO1-GFP biofilms were imaged by confocal microscopy. Transport kinetics of three antibiotics, tobramycin, colistin, and ciprofloxacin, through native mucus and ASMmod were studied, and their activity against PAO1 biofilms grown in different media was assessed by determination of metabolic activity and cfu.

RESULTS

PAO1(-GFP) cultured in human pulmonary mucus or ASMmod showed similarities in bacterial growth and biofilm morphology. A limited permeation of antibiotics through ASMmod was observed, indicating its strong barrier properties, which are comparable to those of native human mucus. Reduced susceptibility of PAO1 biofilms was observed in ASMmod compared with LB medium for tobramycin and colistin, but less for ciprofloxacin.

CONCLUSIONS

These findings underline the importance of mucus as a biological barrier to antibiotics. ASMmod appears to be a valuable surrogate for studying mucus permeation of anti-infectives and their efficacy against PAO1 biofilms.

Akim A, Chong PP. Approaches for Mitigating Microbial Biofilm-Related Drug Resistance: A Focus on Micro- and Nanotechnologies

Biofilms play an essential role in chronic and healthcare-associated infections and are more resistant to antimicrobials compared to their planktonic counterparts due to their (1) physiological state, (2) cell density, (3) quorum sensing abilities, (4) presence of extracellular matrix, (5) upregulation of drug efflux pumps, (6) point mutation and overexpression of resistance genes, and (7) presence of persister cells. The genes involved and their implications in antimicrobial resistance are well defined for bacterial biofilms but are understudied in fungal biofilms. Potential therapeutics for biofilm mitigation that have been reported include (1) antimicrobial photodynamic therapy, (2) antimicrobial lock therapy, (3) antimicrobial peptides, (4) electrical methods, and (5) antimicrobial coatings. These approaches exhibit promising characteristics for addressing the impending crisis of antimicrobial resistance (AMR). Recently, advances in the micro- and nanotechnology field have propelled the development of novel biomaterials and approaches to combat biofilms either independently, in combination or as antimicrobial delivery systems. In this review, we will summarize the general principles of clinically important microbial biofilm formation with a focus on fungal biofilms. We will delve into the details of some novel micro- and nanotechnology approaches that have been developed to combat biofilms and the possibility of utilizing them in a clinical setting.

Inhalable nano into micro dry powders for ivacaftor delivery: The role of mannitol and cysteamine as mucus-active agents

In this paper the innovative approach of nano into micro dry powders (NiM) was applied to incorporate into mannitol or mannitol/cysteamine micromatrices ivacaftor-loaded nanoparticles for pulmonary delivery in CF. Nanoparticles composed by a mixture of two polyhydrohydroxyethtylaspartamide copolymers containing loaded with ivacaftor at 15.5% w/w were produced. The nanoparticles were incorporated into microparticles to obtain NiM that were fully characterized in terms of size, morphology, interactions with artificial Cf mucus (CF-AM) as well as for aerodynamic behaviour. Finally the activity of ivacaftor-containing NiM was evaluated by in vitro preliminary experiments. NiM at matrix composed by a mixture of mannitol:cysteamine showed greater ability to reduce CF-AM viscosity whereas that based on just mannitol showed better aerodynamic properties with a FPF of about 25%. All produced NiM showed very good cytocompatibility and the released ivacaftor was able to restore the chroride transport in vitro.