Solid lipid nanoparticles, an effective carrier for classical antifungal drugs

Solid-lipid nanoparticles (SLNs) are an innovative group of nanosystems used to deliver medicine to their respective targets with better efficiency and bioavailability in contrast to classical formulations. SLNs are less noxious, have fewer adverse effects, have more biocompatibility, and have easy biodegradability. Lipophilic, hydrophilic and hydrophobic drugs can be loaded into SLNs, to enhance their physical and chemical stability in critical environments. Certain antifungal agents used in different treatments are poorly soluble medications, biologicals, proteins etc. incorporated in SLNs to enhance their therapeutic outcome, increase their bioavailability and target specificity. SLNs-based antifungal agents are currently helpful against vicious drug-resistant fungal infections. This review covers the importance of SLNs in drug delivery of classical antifungal drugs, historical background, preparation, physicochemical characteristic, structure and sizes of SLNs, composition, drug entrapment efficacy, clinical evaluations and uses, challenges, antifungal drug resistance, strategies to overcome limitations, novel antifungal agents currently in clinical trials with special emphasis on fungal infections.

Full factorial design, physicochemical characterization, ex vivo investigation, and biological assessment of glutathione-loaded solid lipid nanoparticles for topical application

l-Glutathione (GSH) has exceptional antioxidant activities against UVA irradiation-induced oxidative stress and is used widely for combatting skin ageing. However, topical administration of GSH is challenging due to its inability to penetrate the stratum corneum (SC). This study aims to evaluate the solid lipid nanoparticles (SLNs) carrier system for improving the skin penetration and stability of GSH. The GSH-loaded SLNs (GSH-SLNs) were prepared by the double emulsion technique and were optimized by a full factorial design. The optimized GSH-SLNs formulation had a mean particle size of 305 ± 0.6 nm and a zeta potential of + 20.1 ± 9.5 mV, suitable for topical delivery. The ex-vivo penetration study using human skin demonstrated a 3.7-fold improvement of GSH penetration across SC with GSH-SLNs when compared with aqueous GSH. GSH-SLNs prolonged antioxidant activity on UVA irradiated fibroblast cells when compared to GSH solution, preventing UVA-induced cell death and promoting cell growth for times over 48 h. This research has illustrated that as a carrier system, SLNs were able to enhance the physicochemical stability, skin penetration, and drug deposition in the viable epidermis and dermis layers of the skin for GSH, while also maintaining the ability to protect human skin fibroblast cells against oxidative stress caused by UVA irradiation. This delivery system shows future promise as a topical delivery platform for the topical delivery of GSH and other chemically similar bioactive compounds for improving skin health.

Preparation, Statistical Optimization and In-vitro Characterization of a Dry Powder Inhaler (DPI) Containing Solid Lipid Nanoparticles Encapsulating Amphotericin B: Ion Paired Complexes with Distearoyl Phosphatidylglycerol

The aim of this study was to prepare dry powder inhalers (DPIs) containing amphotericin B-loaded solid lipid nanoparticles (AMB-SLNs) as an alternative approach for prevention of pulmonary aspergillosis. For solubilizing AMB in small amounts of organic solvents ion paired complexes were firstly formed by establishing electrostatic interaction between AMB and distearoyl phosphatidylglycerol (DSPG). The SLN formulations containing AMB-DSPG complexes were prepared using glycerol monostearate (GMS) as the lipid matrix and soybean lecithin and tween 80 as the surfactants by solvent emulsification-evaporation technique. The nanoparticles were optimized through a fractional factorial design. DPIs were prepared by lyophilization technique using lactose as the inhalational carrier and then after, the formulations were evaluated in terms of aerodynamic particle size distribution using an Andersen cascade impactor. The morphology of the particles was examined using scanning electron microscopy (SEM) and in-vitro drug release profiles were evaluated. Following the statistical results, the particle size, Poly dispersity index (PdI), zeta potential, entrapment efficiency (EE%), and drug loading (DL%) of the optimized SLNs were 187.04 ± 11.97 nm, 0.188 ± 0.028, -30.16 ± 1.6 mV, 89.3 ± 3.47 % and 2.76 ± 0.32 %, respectively. Formulation containing 10% w/v of lactose with the calculated fine particle fraction value as 72.57 ± 4.33% exhibited the appropriate aerodynamic characteristics for pulmonary drug delivery. SEM images revealed de-agglomerated particles. In-vitro release studies showed sustained release of AMB from the carriers and the release kinetics were best fitted to the first order kinetic model.

Controlled release of microencapsulated docosahexaenoic acid (DHA) by spray-drying processing

The omega-3-fatty acid, docosahexaenoic acid (DHA) 22:6 n-3, is an important food component for the visual and brain development of infants. In this study two approaches have been explored for the encapsulation of DHA in the pH dependant polymer hydroxyl-propyl-methyl-cellulose-acetate-succinate (HPMCAS). In the first approach Direct Spray Drying (DSD) was implemented for the microencapsulation of DHA/HPMCAS organic solutions, whilst in the second approach solid lipid nanoparticle (SLN) dispersions of DHA, were first produced by high-pressure homogenization, prior to being spray dried in HPMCAS aqueous solutions. The DSD approach resulted in significantly higher quantities of DHA being encapsulated, at 2.09 g/100 g compared to 0.60 g/100 g in the spray-dried SLNs. The DHA stability increased with the direct spray-drying approach. Release studies of DHA in the direct sprayed dried samples revealed a lag time for 2 h in acidic media followed by rapid release in phosphate buffer (pH 6.8).

Nicotinamide loaded functionalized solid lipid nanoparticles improves cognition in Alzheimer's disease animal model by reducing Tau hyperphosphorylation

BACKGROUND

Nicotinamide is considered to be effective in halting the Alzheimer's disease progression. The body could absorb a limited amount of nicotinamide at a time, requiring multiple doses through a day. To overcome such an obstacle which reduces the patient compliance, a sustained/controlled delivery system could be useful.

METHOD

Nicotinamide loaded solid lipid nanoparticles (SLN) were prepared and functionalized with polysorbate 80 (S80), phosphatidylserine (PS) or phosphatidic acid (PA). The acquired particles were characterized and evaluated in respect of their cytotoxicity, biodistribution, and in vivo effectiveness through the different routes of administration.

RESULTS

The optimum sizes of 112 ± 1.6 nm, 124 ± 0.8 nm, and 137 ± 1.05 nm were acquired for S80-, PS-, and PA-functionalized SLNs, respectively. The in vitro cytotoxicity on SH-SY5Y cell line showed the safety of formulations except for S80-functionalized SLNs. Biodistribution study of SLNs has proved the benefits of functionalization in improving the brain delivery. The results of spatial and memory test, i.e. Morris water maze, and also histopathology and biochemical tests demonstrated the effectiveness of i.p. injection of PS -functionalized SLNs in improving the cognition, preserving the neuronal cells and reducing tau hyperphosphorylation in a rat model of Alzheimer's disease.

CONCLUSION

The acquired PS-functionalized SLN could be a potential brain delivery system. Loaded with nicotinamide, an HDAC inhibitor, it could ameliorate the cognition impairment of rats more effectively than the conventional administration of nicotinamide, i.e. oral, in the early stage of Alzheimer's disease. Graphical abstract ᅟ.

Co-delivery of paclitaxel and tanespimycin in lipid nanoparticles enhanced anti-gastric-tumor effect in vitro and in vivo

Combined administration regimens are commonly used in cancer therapy to reduce cell toxicity and drug resistance. In this study, we use solid lipid nanoparticles (SLNs) as drug carriers and sought to investigate the effect of combined administration of paclitaxel (PTX) and tanespimycin (17-AAG) in gastric cancer. The SLNs loaded with paclitaxel and tanespimycin were prepared using the solvent injection method. The effect of encapsulated SLNs on cell viability and colony formation were measured in three human gastric cell lines. Cell apoptosis assay was carried out in MKN45 cells and xenograft model was used to investigate the effect of encapsulated SLNs in vitro and in vivo. The expression levels of proteins involved in oxidative stress and apoptosis were measured by western blotting analysis. The encapsulated SLNs reduced cell viabilities and colony formation in gastric cell lines. These SLNs could also induce apoptosis in MKN45 cells, inhibit growth of xenograft and influence the protein levels of Hsp90, MnSOD, Cleaved caspase 3 and Cleaved PARP. The effect of encapsulated SLNs exceeded that of single treatment of PTX or 17-AAG. The combination administration of PTX or 17-AAG resulted in a synergetic anti-cancer effect, probably via an increased oxidative stress and apoptosis levels.

Physicochemical characterization by AFM, FT-IR and DSC and biological assays of a promising antileishmania delivery system loaded with a natural Brazilian product

The control and treatment of Leishmaniasis, a neglected and infectious disease affecting approximately 12 million people worldwide, are challenging. Leishmania parasites multiply intracellularly within macrophages located in deep skin and in visceral tissues, and the currently employed treatments for this disease are subject to significant drawbacks, such as resistance and toxicity. Thus, the search for new Leishmaniasis treatments is compulsory, and Ocotea duckei Vattimo, a plant-derived product from the biodiverse Brazilian flora, may be a promising new treatment for this disease. In this regard, the aim of this work was to develop and characterize a delivery system based on solid lipid nanoparticles (SLN) that contain the liposoluble lignan fraction (LF) of Ocotea duckei Vattimo, which targets the Leishmania phagolysosome of infected macrophages. LF-loaded SLNs were obtained via the hot microemulsion method, and their physical and chemical properties were comprehensively assessed using PCS, AFM, SEM, FT-IR, DSC, HPLC, kinetic drug release studies, and biological assays. The size of the developed delivery system was 218.85±14.2 nm, its zeta potential was -30 mV and its entrapment efficiency (EE%) was high (the EEs% of YAN [yangambin] and EPI-YAN [epi-yangambin] markers were 94.21±0.40% and 94.20±0.00%, respectively). Microscopy, FT-IR and DSC assays confirmed that the delivery system was nanosized and indicated a core-shell encapsulation model, which corroborated the measured kinetics of drug release. The total in vitro release rates of YAN and EPI-YAN in buffer (with sink conditions attained) were 29.6±8.3% and 34.3±8.9%, respectively, via diffusion through the cellulose acetate membrane of the SLN over a period of 4 h. After 24 h, the release rates of both markers reached approximately 45%, suggesting a sustained pattern of release. Mathematical modeling indicated that both markers, YAN and EPI-YAN, followed matrix diffusion-based release kinetics (Higuchi's model) with an estimated diffusion coefficient (D) of 1.3.10(-6) cm(2)/s. The LF-loaded SLNs were non-toxic to murine macrophages (20-80 μg mL(-1) range) and exerted a prominent anti-leishmanial effect (20 μg mL(-1)). These data suggest this new and well-characterized lipid nanoparticle delivery system safely and effectively kills Leishmania and warrants further clinical investigation.

Preparation of SLN-containing Thermoresponsive In-situ Forming Gel as a Controlled Nanoparticle Delivery System and Investigating its Rheological, Thermal and Erosion Behavior

Various nanoparticles have been investigated as novel drug delivery systems, including solid lipid nanoparticles (SLNs). Due to their rapid clearance from systemic circulation, nanoparticles do not provide sustained action in most cases. Different strategies have been employed to overcome this problem. In this direction, the present study introduces erodible in-situ forming gel systems as potential vehicles for prolonged release of SLNs. SLNs were prepared by solidification of an oil-in-water microemulsion containing stearic acid, surfactants and co-surfactants. Nanoparticles were then dispersed in a thermosensitive Poloxamer 407 aqueous solution (sol) at 4 °C and their effects on gel forming ability, sol-gel transition and rheological behavior of the system were investigated over 5-50 °C. Thermal behavior of the system was investigated by differential scanning calorimetry too. Erosion rate of the gel in the presence and absence of SLN was measured by gravimetric method. Integrity of SLNs in the system was investigated by scanning electron microscopy (SEM) and particle size analysis. SLN showed particle size and zeta potential of 130 ± 1.39 nm and - 44 ± 2.1 mV respectively. Particle size analysis and SEM studies after gel erosion revealed presence of intact SLN in the hydrogel. SLN reduced erosion rate of Poloxamer gel and increased its sol-gel transition temperature from 26 to 29 °C. However, gelling kinetic did not change significantly after addition of SLN. Damping factor <1 indicated stability of the SLN-containing system. Present results indicate potential of sol-gel systems for controlled nanoparticle delivery and show that SLN affects properties of the system.