Alpha-lipoic acid-loaded nanostructured lipid carrier: sustained release and biocompatibility to HaCaT cells in vitro

Nanotechnological Approaches to Enhance the Potential of α-Lipoic Acid for Application in the Clinic

α-lipoic acid is a naturally occurring compound with potent antioxidant properties that helps protect cells and tissues from oxidative stress. Its incorporation into nanoplatforms can affect factors like bioavailability, stability, reactivity, and targeted delivery. Nanoformulations of α-lipoic acid can significantly enhance its solubility and absorption, making it more bioavailable. While α-lipoic acid can be prone to degradation in its free form, encapsulation within nanoparticles ensures its stability over time, and its release in a controlled and sustained manner to the targeted tissues and cells. In addition, α-lipoic acid can be combined with other compounds, such as other antioxidants, drugs, or nanomaterials, to create synergistic effects that enhance their overall therapeutic benefits or hinder their potential cytotoxicity. This review outlines the advantages and drawbacks associated with the use of α-lipoic acid, as well as various nanotechnological approaches employed to enhance its therapeutic effectiveness, whether alone or in combination with other bioactive agents. Furthermore, it describes the engineering of α-lipoic acid to produce poly(α-lipoic acid) nanoparticles, which hold promise as an effective drug delivery system.

Effects of Photodynamic Therapy Using 5 -Aminolevulinic Acid (ALA) Loaded Acrylic Nanoparticles (ANPs) on HaCaT Cells

Objective

ALA-PDT (5-aminolevulinic acid photodynamic therapy) is a central modality in the treatment of skin diseases. Increasing the bioavailability of ALA remains a critical issue. With this in mind, our study explores a novel route of ALA delivery by loading acrylic nanoparticles (ANPs).

Methods

ALA-ANPs were synthesized by emulsion polymerisation and characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). The effects of ALA-ANPs on HaCaT cell line were evaluated, including characteristics, morphological changes, protoporphyrin IX (PpIX) fluorescence kinetics, reactive oxygen species (ROS) levels, mitochondrial membrane potential and ki67 expression in these cells.

Results

The ANPs had uniform sizes, smooth surfaces and excellent light transmittance, with diameters of 150-200 nm. In contrast, the ALA - ANPs had uneven surfaces and poor light transmittance, with diameters of 220-250 nm. During 12 hours of co-incubation of HaCaT cells with ALA, the intracellular accumulation of PpIX increased over time. Notably, after 6 hours of incubation, PpIX levels induced by 1.81 mg/mL ALA-ANPs exceeded those induced by 1.0 mM ALA (p < 0.01). CCK-8 results showed a positive correlation between PDT-induced inhibition of HaCaT cell proliferation and ALA concentration when ALA concentration remained below 2.0 mM. Compared to the 1.0 mM ALA group, the 1.81 mg/mL ALA-ANPs group showed decreased mitochondrial membrane potential, ki67 immunofluorescence intensity and cell proliferation. In contrast, ROS levels were significantly increased in the 1.81 mg/mL ALA-ANPs group (p < 0.01).

Conclusion

Loading ANPs provide improved stability and potency for ALA. The ALA-ANPs-PDT approach has superior inhibitory effects on HaCaT proliferation in vitro.

Synthesis and Evaluation of Metal Lipoate Adhesives

The development of new bioadhesives with integrated properties remains an unmet clinical need to replace staples or sutures. Current bioadhesives do not allow electronic activation, which would allow expansion into laparoscopic and robotic surgeries. To address this deficiency, voltage-activated adhesives have been developed on both carbene- and catechol-based chemical precursors. Herein, a third platform of voltage-activated adhesive is evaluated based on lipoic acid, a non-toxic dithiolane found in aerobic metabolism and capable of ring-opening polymerization. The electro-rheological and adhesive properties of lithium, sodium, and potassium salts of lipoic acid are applied for wet tissue adhesion. At ambient conditions, potassium lipoate displays higher storage modulus than lithium or sodium salt under similar conditions. Voltage stimulation significantly improves gelation kinetics to Na- and K-lipoates, while Li-lipoate is found to not require voltage stimulation for gelation. Lap shear adhesion strength on wetted collagen substrates reveals that the synthetic metal lipoates have comparable adhesion strength to fibrin sealants without viral or ethical risks.

Lipoic Acid Conjugated Boron Hybrids Enhance Wound Healing and Antimicrobial Processes

Complications of chronic non-healing wounds led to the emergence of nanotechnology-based therapies to enhance healing, facilitate tissue repair, and prevent wound-related complications like infections. Here, we design alpha lipoic acid (ALA) conjugated hexagonal boron nitride (hBN) and boron carbide (B₄C) nanoparticles (NPs) to enhance wound healing in human dermal fibroblast (HDFa) cell culture and characterize its antimicrobial properties against Staphylococcus aureus (S. aureus, gram positive) and Escherichia coli (E. coli, gram negative) bacterial strains. ALA molecules are integrated onto hBN and C₄B NPs through esterification procedure, and molecular characterizations are performed by using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and UV-vis spectroscopy. Wound healing and antimicrobial properties are investigated via the use of cell viability assays, scratch test, oxidative stress, and antimicrobial activity assays. Based on our analysis, we observe that ALA-conjugated hBN NPs have the highest wound-healing feature and antimicrobial activity compared to ALA-B₄C. On the other hand, hBN, ALA-B₄C, and ALA compounds showed promising regenerative and antimicrobial properties. Also, we find that ALA conjugation enhances wound healing and antimicrobial potency of hBN and B₄C NPs. We conclude that the ALA-hBN conjugate is a potential candidate to stimulate regeneration process for injuries.

Supplementation of Alpha-lipoic acid-loaded nanoliposomes in semen extender improves freezability of buffalo spermatozoa

This research was designed to explore the protective effect of alpha-lipoic acid-loaded nanoliposomes (ALAN) during cryopreservation of buffalo sperm. Buffalo semen was cryopreserved in a tris-citrate egg yolk extender without any supplement (ALAN0, control group) or with ALAN at levels of 25, 50, 75 or 150 µg (ALAN25, ALAN50, ALAN75 and ALAN150, respectively). The ALAN had a size of 171.80 nm and a negative zeta potential (- 43.40 mV). The progressive motility, vitality and membrane integrity significantly improved in all ALAN groups (except ALAN25 for membrane integrity). ALAN150 group exhibited the best values of progressive sperm motility, vitality and membrane integrity after thawing at 37 °C for 30 s or incubated for 2 h at 37 °C and 5% CO₂ compared with those in other groups. Both ALAN75 and ALAN150 groups significantly improved the TAC, GR and catalase, while lipid peroxidation and early apoptotic spermatozoa significantly decreased in ALAN150 group followed by ALAN75 group. Collectively, the adding ALAN to buffalo semen freezing extender plays a substantial shielding function against cryodamage by preserving the sperm functional parameters.

Graphene 2D platform is safe and cytocompatibile for HaCaT cells growing under static and dynamic conditions

The study concerns the influence of graphene monolayer, as a 2 D platform, on cell viability, cytoskeleton, adhesions sites andmorphology of mitochondria of keratinocytes (HaCaT) under static conditions. Based on quantitative and immunofluorescent analysis, it could be stated that graphene substrate does not cause any damage to membrane or disruption of other monitored parameters. Spindle poles and cytokinesis bridges indicating proliferation of cells on this graphene substrate were detected. Moreover, the keratinocyte migration rate on the graphene substrate was comparable to control glass substrate when the created wound was completely closed after 38 hours. HaCaT morphology and viability were also assessed under dynamic conditions (lab on a chip - micro scale). For this purpose, microfluidic graphene system was designed and constructed. No differences as well as no anomalies were observed during cultivation of these cells on the graphene or glass substrates in relation to cultivation conditions: static (macro scale) and dynamic (micro scale). Only natural percentage of dead cells was determined using different methods, which proved that the graphene as the 2 D platform is cytocompatible with keratinocytes. The obtained results encourage the use of the designed lab on a chip system in toxicity testing of graphene also on other cells and further research on the use of graphene monolayers to produce bio-bandages for skin wounds in animal tests.

PEG-interpenetrated genipin-crosslinked dual-sensitive hydrogel/nanostructured lipid carrier compound formulation for topical drug administration

PEG-interpenetrated dual-sensitive hydrogels that load nano lipid carrier (NLC) were researched and developed for topical drug administration. Natural antioxidant α-lipoic acid (ALA) was selected as our model drug. The α-lipoic acid (ALA) nano lipid carrier was successfully prepared by hot melt emulsification and ultrasonic dispersion method, and the physicochemical properties of the nano lipid carrier were investigated, including morphology, particle distribution, polydispersity coefficient, zeta potential and encapsulation efficiency. Carboxymethyl chitosan and poloxamer 407 contributed to pH- and temperature-sensitive properties in the hydrogel, respectively. Natural non-toxic cross-linking agent genipin reacted with carboxymethyl chitosan to form the hydrogel. Poly ethylene glycol (PEG), a polymer compound with good water solubility and biocompatibility, interpenetrated the hydrogel and influenced the mechanical strength and drug release behaviour. FI-IR test verified the successful synthesis of the hydrogel. The rheological parameters indicated that the mechanical strength of the hydrogel was positively correlated with the amount of PEG, and the in vitro dissolution profiles demonstrated that the increasement of PEG could accelerate the drug release rate. The compatibility of the drug delivery system was verified with cells and mice model. Topical delivery of ALA in solution, NLC and NLC-gel was investigated in-vitro.

Lipid Nanoparticles as Carriers for Bioactive Delivery

Nanotechnology has made a great impact on the pharmaceutical, biotechnology, food, and cosmetics industries. More than 40% of the approved drugs are lipophilic and have poor solubility. This is the major rate-limiting step that influences the release profile and bioavailability of drugs. Several approaches have been reported to administer lipophilic drugs with improved solubility and bioavailability. Nanotechnology plays a crucial role in the targeted delivery of poorly soluble drugs. Nanotechnology-based drug delivery systems can be classified as solid lipid nanoparticulate drug delivery systems, emulsion-based nanodrug delivery systems, vesicular drug delivery systems, etc. Nanotechnology presents a new frontier in research and development to conquer the limitations coupled with the conventional drug delivery systems through the formation of specific functionalized particles. This review presents a bird's eye view on various aspects of lipid nanoparticles as carriers of bioactive molecules that is, synthesis, characterization, advantage, disadvantage, toxicity, and application in the medical field. Update on recent development in terms of patents and clinical trials of solid lipid nanoparticles (SLNs) and nanostructure lipid carriers (NLCs) have also been discussed in this article.

Ezetimibe-Loaded Nanostructured Lipid Carrier Based Formulation Ameliorates Hyperlipidaemia in an Experimental Model of High Fat Diet

Ezetimibe (EZE) possesses low aqueous solubility and poor bioavailability and in addition, its extensive hepatic metabolism supports the notion of developing a novel carrier system for EZE. Ezetimibe was encapsulated into nanostructured lipid carriers (EZE-NLCs) via a high pressure homogenization technique (HPH). A three factor, two level (2³) full factorial design was employed to study the effect of amount of poloxamer 188 (X1), pressure of HPH (X2) and number of HPH cycle (X3) on dependent variables. Particle size, polydispersity index (PDI), % entrapment efficiency (%EE), zeta potential, drug content and in-vitro drug release were evaluated. The optimized formulation displays pragmatic inferences associated with particle size of 134.5 nm; polydispersity index (PDI) of 0.244 ± 0.03; zeta potential of −28.1 ± 0.3 mV; % EE of 91.32 ± 1.8% and % CDR at 24-h of 97.11%. No interaction was observed after X-ray diffraction (XRD) and differential scanning calorimetry (DSC) studies. EZE-NLCs (6 mg/kg/day p.o.) were evaluated in the high fat diet fed rats induced hyperlipidemia in comparison with EZE (10 mg/kg/day p.o.). Triglyceride, HDL-c, LDL-c and cholesterol were significantly normalized and histopathological evaluation showed normal structure and architecture of the hepatocytes. The results demonstrated the superiority of EZE-NLCs in regard to bioavailability enhancement, dose reduction and dose-dependent side effects.

Δ9-Tetrahydrocannabinol Derivative-Loaded Nanoformulation Lowers Intraocular Pressure in Normotensive Rabbits

PURPOSE

Δ9-Tetrahydrocannabinol-valine-hemisuccinate, a hydrophilic prodrug of Δ9-tetrahydrocannabinol, synthesized with the aim of improving the ocular bioavailability of the parent molecule, was investigated in a lipid-based nanoparticle dosage form for ocular delivery.

METHODS

Solid lipid nanoparticles (SLNs) of Δ9-tetrahydrocannabinol-valine-hemisuccinate and Δ9-tetrahydrocannabinol, along with a nanoemulsion of Δ9-tetrahydrocannabinol-valine-hemisuccinate, were tested for glaucoma management in a normotensive rabbit model by using a multiple-dosing protocol. Marketed formulations of timolol maleate and pilocarpine HCl were also tested for their pharmacodynamic profile, post-single dose administration.

RESULTS

A peak intraocular pressure (IOP) drop of 30% from baseline was observed in rabbits treated with SLNs loaded with Δ9-tetrahydrocannabinol-valine-hemisuccinate at 90 minutes. Treated eyes of rabbits receiving Δ9-tetrahydrocannabinol-valine-hemisuccinate SLNs had significantly lower IOP than untreated eyes until 360 minutes, whereas the group receiving the emulsion formulation showed a drop in IOP until 90 minutes only. In comparison to marketed pilocarpine and timolol maleate ophthalmic solutions, Δ9-tetrahydrocannabinol-valine-hemisuccinate SLNs produced a greater effect on IOP in terms of both intensity and duration. In terms of tissue concentrations, significantly higher concentrations of Δ9-tetrahydrocannabinol-valine-hemisuccinate were observed in iris-ciliary bodies and retina-choroid with SLNs.

CONCLUSION

Δ9-Tetrahydrocannabinol-valine-hemisuccinate formulated in a lipid-based nanoparticulate carrier shows promise in glaucoma pharmacotherapy.

TRANSLATIONAL RELEVANCE

Glaucoma therapies usually focus on decreased aqueous humor production and increased outflow. However, such therapy is not curative, and there lies a need in preclinical research to focus efforts on agents that not only affect the aqueous humor dynamics but also provide neuroprotection. Historically, there have been bench-scale studies looking at retinal ganglion cell death post-axonal injury. However, for a smooth translation of this in vitro activity to the clinic, animal models examining IOP reduction, i.e., connecting the neuroprotective activity to a measurable outcome in glaucoma management (IOP), need to be investigated. This study investigated the IOP reduction efficacy of cannabinoids for glaucoma pharmacotherapy in a normotensive rabbit model, bringing forth a new class of agents with the potential of IOP reduction and improved permeation to the back of the eye, possibly providing neuroprotective benefits in glaucoma management.

Toward Smaller Aqueous-Phase Plasmonic Gold Nanoparticles: High-Stability Thiolate-Protected ∼4.5 nm Cores

Most applications of aqueous plasmonic gold nanoparticles benefit from control of the core size and shape, control of the nature of the ligand shell, and a simple and widely applicable preparation method. Surface functionalization of such nanoparticles is readily achievable but is restricted to water-soluble ligands. Here we have obtained highly monodisperse and stable smaller aqueous gold nanoparticles (core diameter ∼4.5 nm), prepared from citrate-tannate precursors via ligand exchange with each of three distinct thiolates: 11-mercaptoundecanoic acid, α-R-lipoic acid, and para-mercaptobenzoic acid. These are characterized by UV-vis spectroscopy for plasmonic properties; Fourier transform infrared (FTIR) spectroscopy for ligand-exchange confirmation; X-ray diffractometry for structural analysis; and high-resolution transmission electron microscopy for structure and size determination. Chemical reduction induces a blueshift, maximally +0.02 eV, in the localized surface plasmon resonance band; this is interpreted as an electronic (-) charging of the monolayer-protected cluster (MPC) gold core, corresponding to a -0.5 V change in electrochemical potential.

Release and permeation profiles of spray-dried chitosan microparticles containing caffeic acid

Caffeic acid (CA), a phenolic compound found in plants with antioxidant and antimicrobial activity, induces collagen production and prevents premature aging of the skin. The objective of this study was to develop two types of chitosan microparticles (MP) containing CA and to relate the morphology with the release and permeation profiles. One type of MP was prepared from a hydroalcoholic solution (MPI) and the other from an aqueous solution (MPII). Their morphology and size was evaluated by high-resolution scanning electron microscopy. The release profile of CA was evaluated using the cellulose membrane from the two MPs in Franz diffusion cells and the permeation profile was evaluated using human abdominal skin samples; the epidermal membranes were prepared by the heat-separation technique. MPII was spherical with a smooth surface, suitable for the controlled release of substances, whereas MPI was porous with non-internalized residual material. This result was consistent with their release and permeation profiles because MPII exhibited a slower and more controlled release than MPI. Thus, the method of preparation of MP and their composition influence the release profile of CA. Therefore, the production conditions must be closely controlled.

Atorvastatin-loaded nanostructured lipid carriers (NLCs): strategy to overcome oral delivery drawbacks

Atorvastatin (AT) is a widely used lipid-regulating drug to reduce cholesterol and triglycerides. Its poor aqueous solubility and hepatic metabolism require development of drug delivery systems able to improve its solubility and bypass hepatic effect. For this purpose, atorvastatin nanostructured lipid carriers (AT-NLCs) were prepared and characterized. AT-NLCs were prepared by emulsification using high-speed homogenization followed by ultrasonication. The prepared NLCs showed particle size between 162.5 ± 12 and 865.55 ± 28 nm while zeta potential values varied between −34 ± 0.29 and −23 ± 0.36 mV. They also showed high encapsulation efficiency (>87%) and amorphous state of the drug in lipid matrix. Pharmacokinetic parameters of optimized formulation (NLC-1; composed of 2% Gelucire^® 43/01, 8% Capryol^® PGMC, 2% Pluronic^®F68 and 0.5% lecithin) revealed 3.6- and 2.1-fold increase in bioavailability as compared to atorvastatin suspension and commercial product (Lipitor^®), respectively. Administration of NLC-1 led to significant reduction (p < .05) in the rats’ serum levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL) and significant increase in high-density lipoprotein (HDL). This improvement was confirmed histologically by minimizing the associated hepatic steatosis. These investigations demonstrated the superiority of NLCs for improvement of oral bioavailability and in vivo performance of AT.

Nanoencapsulation strategies for the delivery of novel bifunctional antioxidant/σ1 selective ligands

Nowadays sigma-1 receptors are considered as new therapeutic objectives for central nervous system neurodegenerative diseases. Among different molecules, alpha lipoic acid has been identified as a natural potent antioxidant drug, whose therapeutic efficacy is limited by its many drawbacks, such as fast metabolism, poor bioavailability and high physico-chemical instability. Alfa-lipoic acid derivatives have been recently developed demonstrating their neuroprotective activity and effectiveness in different types of oxidative stress. In this work, two derivatives containing an amide or an ester functional group with different lipophilicity, were selected for their important affinity for sigma-1 receptors. Herein, in order to improve the in vitro stability and antioxidant effectiveness of alpha-lipoic acid derivatives, we focused our efforts in the nanoencapsulation strategies. Aqueous-core nanocapsules for the delivery of the hydrophilic compound and nanostructured lipid carrier for the lipophilic derivative, were properly designed and prepared using a direct or inverse eco-friendly organic solvent-free procedure. All nanosystems were characterized in terms of mean size, polydispersity, stability, morphology, encapsulation efficiency and in vitro release profiles. In order to evaluate the nanocarriers biocompatibility and antioxidant effectiveness, in vitro biological studies (cell viability, total antioxidant capacity and total oxidative status) were developed on primary human whole blood cell cultures, on both unloaded and derivatives-loaded nanodevices.

Skin delivery of epigallocatechin-3-gallate (EGCG) and hyaluronic acid loaded nano-transfersomes for antioxidant and anti-aging effects in UV radiation induced skin damage

The present work attempts to develop and statistically optimize transfersomes containing EGCG and hyaluronic acid to synergize the UV radiation-protective ability of both compounds, along with imparting antioxidant and anti-aging effects. Transfersomes were prepared by thin film hydration technique, using soy phosphatidylcholine and sodium cholate, combined with high-pressure homogenization. They were characterized with respect to size, polydispersity index, zeta potential, morphology, entrapment efficiency, Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), in vitro antioxidant activity and ex vivo skin permeation studies. Cell viability, lipid peroxidation, intracellular ROS levels and expression of MMPs (2 and 9) were determined in human keratinocyte cell lines (HaCaT). The composition of the transfersomes was statistically optimized by Design of Experiments using Box–Behnken design with four factors at three levels. The optimized transfersome formulation showed vesicle size, polydispersity index and zeta potential of 101.2 ± 6.0 nm, 0.245 ± 0.069 and −44.8 ± 5.24 mV, respectively. FTIR and DSC showed no interaction between EGCG and the selected excipients. XRD results revealed no form conversion of EGCG in its transfersomal form. The optimized transfersomes were found to increase the cell viability and reduce the lipid peroxidation, intracellular ROS and expression of MMPs in HaCaT cells. The optimized transfersomal formulation of EGCG and HA exhibited considerably higher skin permeation and deposition of EGCG than that observed with plain EGCG. The results underline the potential application of the developed transfersomes in sunscreen cream/lotions for improvement of UV radiation-protection along with deriving antioxidant and anti-aging effects.