Imidazole-Based pH-Sensitive Convertible Liposomes for Anticancer Drug Delivery

Development of doxorubicin-encapsulated magnetic liposome@PEG for treatment of breast cancer in BALB/c mice

The magnetic doxorubicin-encapsulated liposome/PEG/Fe3O4 (called as DOX@m-Lip/PEG) was synthesized and studied as a novel nanocarrier for the treatment of breast cancer in BALB/c mice. Nanocarrier was characterized by FT-IR, zeta-potential sizer, EDX elemental analysis, EDX mapping, TEM, and DLS techniques. The results showed that the size of the nanocarrier was determined around 128 nm by TEM. EDX study confirmed PEG-conjugation in the magnetic liposomes and was homogenously distributed in the nanosize range (100-200 nm) with a negative surface charge (-61.7 mV). The kinetic studies indicated that the release of doxorubicin from DOX@m-Lip/PEG follows the Korsmeyer-Peppas model. The n-value of the model was 0.315, indicating that doxorubicin release from the nanocarrier had a slow releasing rate and followed Fick's law. The DOX release from the nanocarrier lasted a long time (more than 300 h). In in vivo part, a mouse 4T1 breast tumor model was used. The in vivo results indicated that DOX@m-Lip/PEG caused much stronger tumor cell necrosis and less cardiotoxic effects than the other groups. In conclusion, we show that m-Lip/PEG is a promising nanocarrier for low dosage and slow release of doxorubicin in treating breast cancer, and treatment with encapsulated DOX (DOX@m-Lip/PEG) demonstrated higher efficacy with low cardiac toxicity. Besides, the magnetic property of m-Lip@PEG nanocarrier allows it to be a potent mater for hyperthermia and MRI studies.

Key Design Features of Lipid Nanoparticles and Electrostatic Charge-Based Lipid Nanoparticle Targeting

Lipid nanoparticles (LNP) have gained much attention after the approval of mRNA COVID-19 vaccines. The considerable number of currently ongoing clinical studies are testament to this fact. These efforts towards the development of LNPs warrant an insight into the fundamental developmental aspects of such systems. In this review, we discuss the key design aspects that confer efficacy to a LNP delivery system, i.e., potency, biodegradability, and immunogenicity. We also cover the underlying considerations regarding the route of administration and targeting of LNPs to hepatic and non-hepatic targets. Furthermore, since LNP efficacy is also a function of drug/nucleic acid release within endosomes, we take a holistic view of charged-based targeting approaches of LNPs not only in the context of endosomal escape but also in relation to other comparable target cell internalization strategies. Electrostatic charge-based interactions have been used in the past as a potential strategy to enhance the drug release from pH-sensitive liposomes. In this review, we cover such strategies around endosomal escape and cell internalization in low pH tumor micro-environments.

A new theranostic pH-responsive niosome formulation for Doxorubicin delivery and bio-imaging against breast cancer

As one of the newest generations of nanoplatforms, smart nanotheranostics have attracted signifivant attentions for medical applications, especially in oncology and cancer treatment. Indeed, their capability to provide treatment and diagnosis simultaneously leads to reduce time and side effects along with improving the performance. This study aims to introduce a novel smart nano-platform composed of doxorubicin-loaded pH-responsive stealth niosomes containing CdSe/ZnS Quantum dots as an imaging agent. Drug loaded nano-platform was fabricated via thin-film hydration method and then evaluated using different physicochemical tests. The entrapment efficiency and release profile of doxorubicin were assessed at three different pH (4, 6.5, and 7.4). Biological features and imaging ability of the nanoparticles were also evaluated by MTT assay, apoptosis assay, and fluorescence microscopy. Results showed that the fabricated nanoparticles were round-shaped, with a mean size of about 100±10 nm, -2 mV surface charge, and about 87% entrapment efficiency. The drug release profile presented a pH-responsive behavior (80, 60, and 40% drug release in pH 4, 6.5, and 7.4, respectively). The bio-activity assessments showed nearly 55% cytotoxicity effects via inducing cell apoptosis. Besides, the uptake of samples by the cells was confirmed through fluorescence imaging. Based on the results, this new nanoformulation could be considered as a candidate for future cancer theranostic applications.

Coarse-Grained Molecular Dynamics of pH-Sensitive Lipids

pH-sensitive lipids represent a class of lipids that can be protonated and destabilized in acidic environments, as they become positively charged in response to low-pH conditions. They can be incorporated into lipidic nanoparticles such as liposomes, which are able to change their properties and allow specific drug delivery at the acidic conditions encountered in some pathological microenvironments. In this work, we used coarse-grained molecular-dynamic simulations to study the stability of neutral and charged lipid bilayers containing POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) and various kinds of ISUCA ((F)2-(imidazol-1-yl)succinic acid)-derived lipids, which can act as pH-sensitive molecules. In order to explore such systems, we used a MARTINI-derived forcefield, previously parameterized using all-atom simulation results. We calculated the average area per lipid, the second-rank order parameter and the lipid diffusion coefficient of both lipid bilayers made of pure components and mixtures of lipids in different proportions, under neutral or acidic conditions. The results show that the use of ISUCA-derived lipids disturbs the lipid bilayer structure, with the effect being particularly marked under acidic conditions. Although more-in depth studies on these systems must be carried out, these initial results are encouraging and the lipids designed in this research could be a good basis for developing new pH-sensitive liposomes.