Novel fatty acid-based pH-responsive nanostructured lipid carriers for enhancing antibacterial delivery

Acid-sensitive prodrugs; a promising approach for site-specific and targeted drug release

Drugs administered through conventional formulations are devoid of targeting and often spread to various undesired sites, leading to sub-lethal concentrations at the site of action and the emergence of undesired effects. Hence, therapeutic agents should be delivered in a controlled manner at target sites. Currently, stimuli-based drug delivery systems have demonstrated a remarkable potential for the site-specific delivery of therapeutic moieties. pH is one of the widely exploited stimuli for drug delivery as several pathogenic conditions such as tumor cells, infectious and inflammatory sites are characterized by a low pH environment. This review article aims to demonstrate various strategies employed in the design of acid-sensitive prodrugs, providing an overview of commercially available acid-sensitive prodrugs. Furthermore, we have compiled the progress made for the development of new acid-sensitive prodrugs currently undergoing clinical trials. These prodrugs include albumin-binding prodrugs (Aldoxorubicin and DK049), polymeric micelle (NC-6300), polymer conjugates (ProLindac™), and an immunoconjugate (IMMU-110). The article encompasses a broad spectrum of studies focused on the development of acid-sensitive prodrugs for anticancer, antibacterial, and anti-inflammatory agents. Finally, the challenges associated with the acid-sensitive prodrug strategy are discussed, along with future directions.

Recent Advances in Pharmaceutical Approaches of Antimicrobial Agents for Selective Delivery in Various Administration Routes

Globally, the increase of pathogenic bacteria with antibiotic-resistant characteristics has become a critical challenge in medical treatment. The misuse of conventional antibiotics to treat an infectious disease often results in increased resistance and a scarcity of effective antimicrobials to be used in the future against the organisms. Here, we discuss the rise of antimicrobial resistance (AMR) and the need to combat it through the discovery of new synthetic or naturally occurring antibacterial compounds, as well as insights into the application of various drug delivery approaches delivered via various routes compared to conventional delivery systems. AMR-related infectious diseases are also discussed, as is the efficiency of various delivery systems. Future considerations in developing highly effective antimicrobial delivery devices to address antibiotic resistance are also presented here, especially on the smart delivery system of antibiotics.

Recent advances in responsive antibacterial materials: design and application scenarios

Bacterial infection is one of the leading causes of death globally, although modern medicine has made considerable strides in the past century. As traditional antibiotics are suffering from the emergence of drug resistance, new antibacterial strategies are of great interest. Responsive materials are appealing alternatives that have shown great potential in combating resistant bacteria and avoiding the side effects of traditional antibiotics. In this review, the responsive antibacterial materials are introduced in terms of stimulus signals including intrinsic (pH, enzyme, ROS, etc.) and extrinsic (light, temperature, magnetic fields, etc.) stimuli. Their biomedical applications in therapeutics and medical devices are then discussed. Finally, the author's perspective of the challenge and the future of such a system is provided.

Micron and nano hybrid ufasomes from conjugated linoleic acid, their vesiculation and encapsulation of ginsenoside Rg3

BACKGROUND

Unsaturated fatty acids used to form unstable micro-vesicles, while conjugate linoleic acid (CLA)-sodium dodecyl sulfate (SDS) can self-assembly to stable nano-conjugate linoleic acid vesicles (nano-CLAVs). Generally, micro-capsule could geometrically provide higher loading capacity but also generate concerns in construction convenience, sustained release, bioaccessibility and stability. Hence there is a contradiction between loading capacity and encapsulation efficiency. Therefore, the study of the factors that decide the capsule size falling in nano or micron size with same capsule material would be a benefit to food or drug delivery science.

RESULTS

The micron- and nano-CLAVs were constructed for encapsulation and sustained release of ginsenoside Rg3. The formation mechanism of nano or micron capsule,s the effect of vesicle sizes on encapsulation efficiency, drug loading efficiency and stability of the encapsulated Rg3 were investigated. It was found that with the addition of salt (PBS), the size of CLAVs jumped from nano to micron. Furthermore, the salt concentration is the key factor that decides the vesicle size of nano or micron. The pH at fabrication triggers the vesiculation and dramatically affects the vesicle size over the nano and micron scales.

CONCLUSION

Compared to the nano-CLAVs, micron vesicles enhanced the loading capacity to 137.6% and the encapsulation efficiency to 138.4%, respectively. Meanwhile, the micron-CLAVs performed similar sustained release of Rg3 as the nano-CLAVs did, and was stable for 120 days at room temperature or sustained 98.9% of capsules after centrifuge at 6090 × g for 20 min. © 2022 Society of Chemical Industry.

Nanophyto-gel against multi-drug resistant Pseudomonas aeruginosa burn wound infection

Burn wound is usually associated by antibiotic-resistant Pseudomonas aeruginosa infection that worsens and complicates its management. An effective approach is to use natural antibiotics such as cinnamon oil as a powerful alternative. This study aims to investigate topical nanostructured lipid carrier (NLC) gel loaded cinnamon oil for Pseudomonas aeruginosa wound infection. A 2⁴ full factorial design was performed to optimize the formulation with particle size 108.48 ± 6.35 nm, zeta potential -37.36 ± 4.01 mV, and EE% 95.39 ± 0.82%. FTIR analysis revealed no excipient interaction. Poloxamer 407 in a concentration 20% w/w NLC gel was prepared for topical application. Drug release exhibited an initial burst release in the first five hours, followed by a slow, sustained release of up to five days. NLC-cinnamon gel has a significant ability to control the drug release with the lowest minimum inhibitory concentration again P. aeruginosa compared to other formulations (p < .05). In vivo study also showed NLC-cinnamon gel effectively healed the infected burned wound after a six-day treatment course with better antibacterial efficacy in burned animal models. Histological examination ensured the tolerability of NLC-cinnamon gel. The results suggest that nanoparticle-based cinnamon oil gel is a promising natural product against antibiotic-resistant strains of P. aeruginosa in wound infection.

A transferosome-loaded bigel for enhanced transdermal delivery and antibacterial activity of vancomycin hydrochloride

Transdermal drug delivery is an attractive route of administration relative to other routes as it offers enhanced therapeutic efficacy. However, due to poor skin permeability of certain drugs, their application in transdermal delivery is limited. The ultra-deformable nature of transferosomes makes them suitable vehicles for transdermal delivery of drugs that have high molecular weights and hydrophilicity. However, their low viscosity, which leads to low contact time on the surface of the skin, has restricted their application in transdermal delivery. Therefore, this study aimed to deliver transferosomes loaded with a highly water-soluble and high molecular weight vancomycin hydrochloride (VCM-HCl) via a bigel for systemic delivery and treatment of microbial infections. VCM-HCl-loaded transferosomal formulations (TNFs) were prepared using a reverse-phase evaporation method and then loaded into a bigel. Both the TNFs and TNFs-loaded bigel (TNF-L-B) were characterized by a range of in vitro and ex vivo techniques. TNFs and TNF-L-B were tested for biosafety via the MTT assay and found to be biosafe. Prepared TNFs had sizes, zeta potential and entrapment efficiency of 63.02 ± 5.34 nm, -20.93 ± 6.13 mV and 84.48 ± 1.22% respectively. VCM-HCl release from TNF-L-B showed a prolonged release profile with 39.76 ± 1.6% after 24hrs when compared to bare VCM-HCl loaded in the bigel (74.81 ± 8.84%). Ex-vivo permeation of prepared TNF-L-B showed a higher permeation flux of 0.56 µg/cm²/h compared to the bare VCM-HCl-loaded bigel of 0.23 µg/cm²/h, indicating superior permeation and bioavailability of the drug. Additionally, the prepared TNF-L-B demonstrated improved antimicrobial activity. The TNF-L-B showed minimum inhibitory concentrations (MIC) of 0.97 μg/ml against Staphylococcus aureus (SA) and 1.95 μg/ml against methicillin-resistant SA (MRSA), which were 2-fold lower MIC values than the bare drug. The time-kill assay showed that both TNFs and TNF-L-B systems caused a 5.6-log reduction (100%) in MRSA compared to bare VCM-HCl after 24 hrs of incubation. Furthermore, as opposed to the bare VCM-HCl solution, the degree of biofilm reduction caused by TNFs (55.72%) and TNF-L-B (34.58%) suggests their dominance in eradicating MRSA biofilm. These findings indicate that TNF-L-B is a promising system for transdermal delivery of hydrophilic and high molecular weight drugs.

Biomimetic pH/lipase dual responsive vitamin-based solid lipid nanoparticles for on-demand delivery of vancomycin

In this study, ascorbyl tocopherol succinate (ATS) was designed, synthesized and characterized via FT-IR, HR-MS, H¹ NMR and C¹³ NMR, to simultaneously confer biomimetic and dual responsive properties of an antibiotic nanosystem to enhance their antibacterial efficacy and reduce antimicrobial resistance. Therefore, an in silico-aided design (to mimic the natural substrate of bacterial lipase) was employed to demonstrate the binding potential of ATS to lipase (-32.93 kcal/mol binding free energy (ΔG_bind) and bacterial efflux pumps blocking potential (NorA ΔG_bind: -37.10 kcal/mol, NorB ΔG_bind: -34.46 kcal/mol). ATS bound stronger to lipase than the natural substrate (35 times lower Kd value). The vancomycin loaded solid lipid nanoparticles (VM-ATS-SLN) had a hydrodynamic diameter, zeta potential, polydispersity index and entrapment efficiency of 106.9 ± 1.4 nm, -16.5 ± 0.93 mV, 0.11 ± 0.012 and 61.9 ± 1.31%, respectively. In vitro biocompatibility studies revealed VM-ATS-SLN biosafety and non-haemolytic activity. Significant enhancement in VM release was achieved in response to acidified pH and lipase enzyme, compared to controls. VM-ATS-SLN showed enhanced sustained in vitro antibacterial activity for 5 days, 2-fold greater MRSA biofilm growth inhibition and 3.44-fold reduction in bacterial burden in skin infected mice model compared to bare VM. Therefore, ATS shows potential as a novel multifunctional adjuvant for effective and targeted delivery of antibiotics.

Effect of Carbon Chain Length, Ionic Strength, and pH on the In Vitro Release Kinetics of Cationic Drugs from Fatty-Acid-Loaded Contact Lenses

This paper explores the use of fatty acids in silicone hydrogel contact lenses for extending the release duration of cationic drugs. Drug release kinetics was dependent on the carbon chain length of the fatty acid loaded in the lens, with 12-, 14- and 18-carbon chain length fatty acids increasing the uptake and the release duration of ketotifen fumarate (KTF) and tetracaine hydrochloride (THCL). Drug release kinetics from oleic acid-loaded lenses was evaluated in phosphate buffer saline (PBS) at different ionic strengths (I = 167, 500, 1665 mM); the release duration of KTF and THCL was decreased with increasing ionic strength of the release medium. Furthermore, the release of KTF and THCL in deionized water did not show a burst and was significantly slower compared to that in PBS. The release kinetics of KTF and THCL was significantly faster when the pH of the release medium was decreased from 7.4 towards 5.5 because of the decrease in the relative amounts of oleate anions in the lens mostly populated at the polymer–pore interfaces. The use of boundary charges at the polymer–pore interfaces of a contact lens to enhance drug partition and extend its release is further confirmed by loading cationic phytosphingosine in contact lenses to attract an anionic drug.

Nanotechnology-based lipid systems applied to resistant bacterial control: A review of their use in the past two decades

The rate of infections caused by resistant bacteria to the antimicrobials available for human use grows exponentially every year, which generates major impacts on human health and the world economy. In the last two decades, human beings can witness the expressive increase in the Science and Technology worldwide, and areas such as Health Sciences have benefited from these advances in favor of human health, such as the advent of Pharmaceutical Nanotechnology as an important approach applied for bacterial infections treatment with resistance profile to available antibiotics. This review of the scientific literature brings the applicability of nanotechnology-based lipid systems as an innovative tool in the improvement of bacterial infections treatment. Important studies involving the use of liposomes, solid lipid nanoparticles, nanostructured lipid carriers, nanoemulsions, microemulsions and lipid nanocapsules were verified in the period from 2000 to 2020, where important scientific results were found and will serve as a basis for the use of these systems to remain in constant updating. This manuscript shows the use of these drug delivery systems as potential vehicles for antibacterial compounds, which opens a new hope in the complement of the antibacterial therapeutic arsenal. Important studies developed in the last 20 years are present in this review, and thus guarantees an update on the use of these drug delivery systems for researchers from different areas of Health Sciences.

Co-delivery of hesperidin and clarithromycin in a nanostructured lipid carrier for the eradication of Helicobacter pylori in vitro

Effective and precise eradication of Helicobacter pylori (H. pylori) is the most promising approach to avoid H. pylori-related gastrointestinal disorders. The present study was conducted to demonstrate the efficacy of the co-delivery of hesperidin (Hesp) and clarithromycin (CLR) in nanostructured lipid carriers (NLCs) against H. pylori. We have produced a new delivery system by combining bioflavonoid Hesp and CLR NLCs to address the failure in single antibiotic therapies. Briefly, a blend of solid lipid, liquid lipid, and surfactant was used. Homogeneous NLCs with all the formulations showed a nano size and surface-negative charge and presented high in vitro stability and slow release of the drug even after 24 h. Bioimaging studies by scanning electron microscopy, transmission electron microscopy, and imaging flow cytometry indicated that NLCs interacted with the membrane by adhering to the outer cell membrane and disrupted the membrane that resulted in the leakage of cytoplasmic contents. The prepared NLCs provide sustained and controlled drug release that can be used to increase the rate of H. pylori eradication.

Intrinsic stimuli-responsive nanocarriers for smart drug delivery of antibacterial agents-An in-depth review of the last two decades

Antibiotic resistance due to suboptimal targeting and inconsistent antibiotic release at bacterial infection sites has driven the formulation of stimuli-responsive nanocarriers for antibacterial therapy. Unlike conventional nanocarriers, stimuli-responsive nanocarriers have the ability to specifically enhance targeting and drug release profiles. There has been a significant escalation in the design and development of novel nanomaterials worldwide; in particular, intrinsic stimuli-responsive antibiotic nanocarriers, due to their enhanced activity, improved targeted delivery, and superior potential for bacterial penetration and eradication. Herein, we provide an extensive and critical review of pH-, enzyme-, redox-, and ionic microenvironment-responsive nanocarriers that have been reported in literature to date, with an emphasis on the mechanisms of drug release, the nanomaterials used, the nanosystems constructed and the antibacterial efficacy of the nanocarriers. The review also highlights further avenues of research for optimizing their potential and commercialization. This review confirms the potential of intrinsic stimuli-responsive nanocarriers for enhanced drug delivery and antibacterial killing. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

pH-Responsive Micelles From an Oleic Acid Tail and Propionic Acid Heads Dendritic Amphiphile for the Delivery of Antibiotics

The aim of this study was to synthesize a novel biocompatible pH-responsive oleic acid-based dendritic lipid amphiphile (OLA-SPDA) which self-assembled into stable micelles (OLA-SPDA -micelles) with a relatively low critical micelle concentration (CMC) of 5.6 × 10^-6 M. The formulated micelles had particle size, polydispersity index (PDI) and zeta potential (ZP) of 84.16 ± 0.184 nm, 0.199 ± 0.011 and -42.6 ± 1.98 mV, respectively, at pH 7.4. The vancomycin (VCM) encapsulation efficiency was 78.80 ± 3.26%. The micelles demonstrated pH-responsiveness with an increase in particle size to 141.1 ± 0.0707 nm and a much faster release profile at pH 6.0, as compared to pH 7.4. The minimum inhibitory concentration (MIC) of VCM-OLA-SPDA-micelle against methicillin-resistant staphylococcus aureus (MRSA) was 8-fold lower compared to bare VCM, and the formulation had a 4-fold lower MIC at pH 6.0 when compared to the formulation's MIC at pH 7.4. MRSA viability assay showed the micelles had a percentage killing of 93.39% when compared bare-VCM (58.21%) at the same MIC (0.98 μg/mL). In vivo mice (BALB/c) skin infection models showed an 8-fold reduction in MRSA burden after treatment with VCM-OLA-SPDA-micelles when compared with bare VCM. The above results suggest that pH-responsive VCM-OLA-SPDA-micelles has the potential to be an effective carrier to enhance therapeutic outcomes against infections characterised by low pH.

Vesicles as antibiotic carrier: State of art

Antimicrobial resistance (AMR) has become a global health problem. Bacteria are able to adapt to different environments, with the presence or absence of a host, forming colonies and biofilms. In fact, biofilm formation confers chemical protection to the microbial cells, thus making most of the conventional antibiotics ineffective. Prevention and destruction of biofilms is a challenging task that should be addressed by a multidisciplinary approach from different research fields. One of the medical strategies used against biofilms is the therapy with drug delivery systems. Lipidic nanovesicles are a good choice for encapsulating drugs, increasing their pharmacodynamics and reducing side effects. These soft nanovesicles show significant advantages for their high biocompatibility, physical and chemistry properties, good affinity with drugs, and easy route of administration. This review summarizes the current knowledge on different types of vesicles which may be used as antibiotic carriers. The main preparation and purification methods for the synthesis of these vesicles are also presented. The advantages of drug encapsulation are critically reviewed. In addition, recent works on endolysin formulations as novel, "greener" and efficient antibiofilm solution are included. This paper can provide useful background for the design of novel efficient formulations and synergistic nanomaterials and could be also useful at the pharmaceutical industry to develop wastewater treatments and reduce the antibiotics in the environmental waters.

Nanomedicine Fight against Antibacterial Resistance: An Overview of the Recent Pharmaceutical Innovations

Based on the recent reports of World Health Organization, increased antibiotic resistance prevalence among bacteria represents the greatest challenge to human health. In addition, the poor solubility, stability, and side effects that lead to inefficiency of the current antibacterial therapy prompted the researchers to explore new innovative strategies to overcome such resilient microbes. Hence, novel antibiotic delivery systems are in high demand. Nanotechnology has attracted considerable interest due to their favored physicochemical properties, drug targeting efficiency, enhanced uptake, and biodistribution. The present review focuses on the recent applications of organic (liposomes, lipid-based nanoparticles, polymeric micelles, and polymeric nanoparticles), and inorganic (silver, silica, magnetic, zinc oxide (ZnO), cobalt, selenium, and cadmium) nanosystems in the domain of antibacterial delivery. We provide a concise description of the characteristics of each system that render it suitable as an antibacterial delivery agent. We also highlight the recent promising innovations used to overcome antibacterial resistance, including the use of lipid polymer nanoparticles, nonlamellar liquid crystalline nanoparticles, anti-microbial oligonucleotides, smart responsive materials, cationic peptides, and natural compounds. We further discuss the applications of antimicrobial photodynamic therapy, combination drug therapy, nano antibiotic strategy, and phage therapy, and their impact on evading antibacterial resistance. Finally, we report on the formulations that made their way towards clinical application.