Comparative Experimental and Computational Study of Monoalkyl Chain Phosphatidylcholine-Containing Thermoresponsive Liposomes

Berberine loaded thermosensitive lipid nanoparticles: in vitro characterization, in silico study, and in vivo anti-arthritic effect

Thermoresponsive drug delivery systems have been used to treat diseases that cause hyperthermia or elevated body tissue temperatures, viz., rheumatoid arthritis and different cancers. The aim of the study was to enhance berberine (BER) release using thermosensitive nanostructured lipid carriers (TNLCs) through intra-articular administration for the management of arthritis. TNLCs were prepared using binary mixtures of stearic acid and decanoic acid as solid and liquid lipids, respectively. Lipid mixtures with an optimum melting point were assessed using differential scanning calorimetry studies. In vitro characterization of the BER TNLCs included particle size, zeta potential, entrapment efficiency, and drug release at 37 °C and 41 °C. Joint diameter measurement, real-time polymerase chain reaction (RT-PC) analysis, enzyme-linked immunosorbent assay (ELISA) for inflammatory markers, and histological evaluation of the dissected joints were all performed in vivo on rats with adjuvant-induced arthritis. In vitro characterization revealed negatively charged BER-loaded TNLCs with a spherical shape, particle size less than 500 nm, BER entrapment efficiency up to 79%, and a high drug release rate at an elevated temperature of 41 °C. In silico studies revealed the affinity of BER to different formula components and to the measured biomarkers. In vivo assessment of the optimum TNLCs showed that BER TNLCs were superior to the BER solution suspension regarding their effect on inflammatory biomarkers, joint diameter, and histological studies.

Carbon Dots-Biomembrane Interactions and Their Implications for Cellular Drug Delivery

The effect of carbon dots (CDs) on a model blayer membrane was studied as a means of comprehending their ability to affect cell membranes. Initially, the interaction of N-doped carbon dots with a biophysical liposomal cell membrane model was investigated by dynamic light scattering, z-potential, temperature-modulated differential scanning calorimetry, and membrane permeability. CDs with a slightly positive charge interacted with the surface of the negative-charged liposomes and evidence indicated that the association of CDs with the membrane affects the structural and thermodynamic properties of the bilayer; most importantly, it enhances the bilayer's permeability against doxorubicin, a well-known anticancer drug. The results, like those of similar studies that surveyed the interaction of proteins with lipid membranes, suggest that carbon dots are partially embedded in the bilayer. In vitro experiments employing breast cancer cell lines and human healthy dermal cells corroborated the findings, as it was shown that the presence of CDs in the culture medium selectively enhanced cell internalization of doxorubicin and, subsequently, increased its cytotoxicity, acting as a drug sensitizer.

A combination drug delivery system employing thermosensitive liposomes for enhanced cell penetration and improved in vitro efficacy

Drug-loaded thermosensitive liposomes are investigated as drug delivery systems in combination with local mild hyperthermia therapy due to their capacity to release their cargo at a specific temperature range (40-42 °C). Additional benefit can be achieved by the development of such systems that combine two different anticancer drugs, have cell penetration properties and, when heated, release their drug payload in a controlled fashion. To this end, liposomes were developed incorporating at low concentration (5 mol%) a number of monoalkylether phosphatidylcholine lipids, encompassing the platelet activating factor, PAF, and its analogues that induce thermoresponsiveness and have anticancer biological activity. These thermoresponsive liposomes were efficiently (>90%) loaded with doxorubicin (DOX), and their thermal properties, stability and drug release were investigated both at 37 ^◦C and at elevated temperatures. In vitro studies of the most advantageous liposomal formulation containing the methylated PAF derivative (methyl-PAF, edelfosine), an established antitumor agent, were performed on human prostate cancer cell lines. This system exhibits controlled release of DOX at 40-42 °C, enhanced cell uptake due to the presence of methyl-PAF, and improved cell viability inhibition due to the combined action of both medications.

Current developments in drug delivery with thermosensitive liposomes

Thermosensitive liposomes (TSLs) have been an important research area in the field of tumor targeted chemotherapy. Since the first TSLs appeared that using 1,2-dipalmitoyl-sn-glyce-ro-3-phosphocholine (DPPC) as the primary liposomal lipid, many studies have been done using this type of liposome from basic and practical aspects. While TSLs composed of DPPC enhance the cargo release near the phase transition temperature, it has been shown that many factors affect their temperature sensitivity. Thus numerous attempts have been undertaken to develop new TSLs for improving their thermal response performance. The main objective of this review is to introduce the development and recent update of innovative TSLs formulations, including combination of radiofrequency ablation (RFA), high-intensity focused ultrasound (HIFU), magnetic resonance imaging (MRI) and alternating magnetic field (AMF). In addition, various factors affecting the design of TSLs, such as lipid composition, surfactant, size and serum components are also discussed.

Enhanced blood brain barrier permeability and glioblastoma cell targeting via thermoresponsive lipid nanoparticles

Thermoresponsive targeting is used to deliver therapeutic agents at hyperthermic conditions (39-45 °C). However, available thermoresponsive drug delivery systems (TDDS), including liposomes, have a complex method of preparation involving toxic solvents and reagents. The objective of this in vitro study was to prepare and characterize thermoresponsive lipid nanoparticles (TLN) for treating glioblastoma, the most aggressive brain tumor whose treatment is limited by a low blood brain barrier (BBB) permeability of drugs. Thermoresponsive lipids were prepared by mixing liquid and solid fatty acids (0.1 : 1 to 2 : 1 ratio) and lipid mixtures exhibiting a solid-liquid phase transition at 39 °C were identified by plotting melting point against liquid contents. TLN were prepared by a hot melt encapsulation method using mono- or double-surfactant systems. TLN showed desirable size (<270 nm), zeta potential (-35 to -50 mV), spherical morphology and stability by FTIR studies. In the drug release studies, paclitaxel release was slow at 37 °C, however, it was released abruptly at 39 °C due to the faster diffusion rate from liquid state nanoparticles. During cytotoxicity studies, the unloaded TLN were non-toxic whereas paclitaxel loaded TLN showed higher cytotoxicity to glioblastoma cells at 39 °C (69% cell viability after one hour) compared to 37 °C (82% cell viability). The TLN showed higher permeability across an in vitro model of BBB at 39 °C due to a deformable liquid state which can squeeze through the tight junctions of the BBB. In conclusion, this study demonstrated that the TLN can be used as a safe and effective alternative to traditional TDDS with higher potential to target glioblastoma cells across the BBB.