Rapid and improved oral absorption of N-butylphthalide by sodium cholate-appended liposomes for efficient ischemic stroke therapy

As a multi-target drug to treat ischemic stroke, N-butylphthalide (NBP) is extremely water-insoluble and exhibits limited oral bioavailability, impeding its wide oral application. Effective treatment of ischemic stroke by NBP requires timely and efficient drug exposure, necessitating the development of new oral formulations. Herein, liposomes containing biosurfactant sodium cholate (CA-liposomes) were systemically investigated as an oral NBP delivery platform because of its high biocompatibility and great potential for clinical applications. The optimized liposomes have a uniform hydrodynamic size of 104.30 ± 1.60 nm and excellent encapsulation efficiency (93.91 ± 1.10%). Intriguingly, NBP-loaded CA-liposomes produced rapid drug release and the cumulative release was up to 88.09 ± 4.04% during 12 h while that for NBP group was only 6.79 ± 0.99%. Caco-2 cell monolayer assay demonstrated the superior cell uptake and transport efficiency of NBP-loaded CA-liposomes than free NBP, which was mediated by passive diffusion via transcellular and paracellular routes. After oral administration to rats, NBP-loaded CA-liposomes exhibited rapid and almost complete drug absorption, with a t_max of 0.70 ± 0.14 h and an absolute bioavailability of 92.65% while NBP suspension demonstrated relatively low bioavailability (21.7%). Meanwhile, NBP-loaded CA-liposomes produced 18.30-fold drug concentration in the brain at 5 min compared with NBP suspension, and the brain bioavailability increased by 2.48-fold. As expected, NBP-loaded CA-liposomes demonstrated significant therapeutic efficacy in a middle cerebral artery occlusion rat model. Our study provides new insights for engineering oral formulations of NBP with fast and sufficient drug exposure against ischemic stroke in the clinic.

Ellipticine, its Derivatives: Re-evaluation of Clinical Suitability with the Aid of Drug Delivery Systems

Targeted drug delivery systems gave newer dimensions for safer and more effective use of therapeutic drugs, thus helping in circumventing the issues of toxicity and unintended drug accumulation. These ongoing developments in delivery systems can, in turn, bring back drugs that suffered various limitations, Ellipticine (EPT) being a candidate. EPT derivatives witnessed entry into clinical settings but failed to survive in clinics citing various toxic side effects. A large body of preclinical data deliberates the potency of drug delivery systems in increasing the efficiency of EPT/derivatives while decreasing their toxic side effects. Recent developments in drug delivery systems provide a platform to explore EPT and its derivatives as good clinical candidates in treating tumors. The present review deals with delivery mechanisms of EPT/EPT derivatives as antitumor drugs, in vitro and in vivo, and evaluates the suitability of EPT-carriers in clinical settings.

Hydrophobically Driven Morphologically Diverse Self-Assembled Architectures of Deoxycholate and Imidazolium-Based Biamphiphilic Ionic Liquids in Aqueous Medium

Biamphiphilic ionic liquids (BAILs) having amphiphilic cation and anion are thought to exhibit improved surface activity and colloidal stability to be utilized in different applications. For their effective use, a control over synergetic hydrophobic and electrostatic interactions between oppositely charged ions along with the possibility of tuning of hydrophobicity of the core of aggregates is required. Focusing on this, new BAILs comprising a bile salt anion, deoxycholate, [DC]^-, and 1-alkyl-3-methylimidazolium cations, [C _nmim]⁺ ( n = 2, 4, 6, 8, and 12), were synthesized and characterized for their behavior at air-solution interface as well as in bulk. The synthesized BAILs exhibit high surface activity and self-assemble in the form of different architectures ranging from nanosheets (NSs), nanorods, and vesicles with varying hydrophobicities of the formed core of aggregates, depending on the length of alkyl chain of [C _nmim]⁺. Analysis of various parameters obtained from investigated techniques suggested the changing role of [C _nmim]⁺ from a counterion ( n = 2 and 4) to a cosurfactant ( n = 8 and 12) via a borderline case of [C₆mim]⁺. This changeover in the nature of counterion controlled by hydrophobicity of alkyl chain resulted in morphological diversification in self-assembled architectures via varying set of interactions. It is believed that the present work would offer new perspectives in the self-assembly phenomenon of surfactants in general and surface active ionic liquids in particular to devise new strategies for inducing morphology-dependent functionality in self-assembled structures of BAILs.

Curcumin encapsulated zeolitic imidazolate frameworks as stimuli responsive drug delivery system and their interaction with biomimetic environment

Metal organic frameworks (MOFs) exhibit unique features of finely tunable pore structures, excellent chemical stability and flexible surface structural functionality, making them advantageous for a wide range of applications including energy storage, compound separation, catalysis, and drug delivery. The present work enlightens a novel approach of single step fabrication of CCM-ZIF-8 as a drug carrier and its application as stimuli responsive drug delivery systems via external stimuli involving change in pH and in presence of biomimetic cell membrane like environment using liposomes and SDS micelles. The methodology is devoid of any post synthesis drug loading steps. The synthesized curcumin encapsulated ZIF-8 frameworks demonstrate ultrahigh drug encapsulation efficiency (ca. 83.33%) and good chemical stability. In vitro drug release of curcumin was three times higher in acidic medium than in physiological pH. Cytotoxicity results demonstrated enhanced therapeutic effect of CCM-ZIF-8 than free curcumin. Confocal microscopy results confirmed the easy cellular internalization of CCM-ZIF-8 in HeLa cells. Intracellular distribution studies at various incubation times confirmed the clathrin-mediated endocytosis to lysosomal pathway of CCM-ZIF-8, but without mitochondria being an intracellular fate. The results signify that CCM-ZIF-8 is an efficient drug carrier for passive tumor therapy in future for cancer treatments.

Spectroscopic Investigation of the Interaction of the Anticancer Drug Mitoxantrone with Sodium Taurodeoxycholate (NaTDC) and Sodium Taurocholate (NaTC) Bile Salts

The focus of the present work was to investigate the interaction of the anticancer drug mitoxantrone with two bile salts, sodium taurodeoxycholate (NaTDC) and sodium taurocholate (NaTC). Ultraviolet-visible (UV-Vis) absorption and electron paramagnetic resonance (EPR) spectroscopy were used to quantify the interaction and to obtain information on the location of mitoxantrone in bile salt micelles. The presence of submicellar concentrations of both bile salts induces mitoxantrone aggregation and the extent of drug aggregation in NaTDC is higher than in NaTC. For micellar bile salts concentrations, mitoxantrone monomers are entrapped in the micellar core. Binding constants, micelle/water partition coefficients and the corresponding thermodynamic parameters for binding and partitioning processes were estimated using the changes in monomer absorbance in the presence of bile salts. Binding interaction of mitoxantrone is stronger for NaTDC than NaTC micelles, whereas partitioning efficiency is higher for NaTC micelles for all investigated temperatures. Thermodynamic parameters indicate that both binding and partitioning processes are spontaneous and entropy controlled. The spectral behavior and thermodynamic parameters indicate distinct types of mitoxantrone interaction with NaTDC and NaTC micelles supported by the differences in nature and structure of bile salts micelles.

Tuning of resonance energy transfer from 4′,6-diamidino-2-phenylindole to an ultrasmall silver nanocluster across the lipid bilayer

Liposome mediated efficient tuning of FRET between photoexcited 4′,6-diamidino-2-phenylindole (DAPI) and an ultrasmall silver nanocluster (Ag NC) has been demonstrated using steady-state and time-resolved fluorescence spectroscopy.

First Evidence of the Liposome-Mediated Deintercalation of Anticancer Drug Doxorubicin from the Drug-DNA Complex: A Spectroscopic Approach

Biocompatible liposomes were used for the first time to study the deintercalation process of a prominent anticancer drug, doxorubicin (DOX), from doxorubicin-intercalated DNA (DOX-DNA complex) under controlled experimental conditions. The study revealed that anionic liposomes (DMPG liposomes) appeared to be the most effective to bring in the highest percentage of drug release while cationic liposomes (DOTAP liposomes) scored the lowest percentage of release. The drug release was primarily attributed to the electrostatic interaction between liposomes and drug molecules. Apart from this interaction, changes in the hydrophobicity of the medium upon addition of liposomes to the DNA-drug solution accompanied by lipoplex formation between DNA and liposomes were also attributed to the observed deintercalation. The CD and the time-resolved rotational relaxation studies confirmed that lipoplex formation took place between liposomes and DNA owing to electrostatic interaction. The confocal study revealed that in the postrelease period, DOX binds with liposomes. The reason behind the binding is electrostatic interaction as well as the unique bilayer structure of liposomes which helps it to act as a "hydrophobic sink" for DOX. The study overall highlighted a novel strategy for deintercalation of drug using biocompatible liposomes, as the release of the drug can be controlled over a period of time by varying the concentration and composition of the liposomes.

Partitioning of prototropic species of an anticancer drug ellipticine in bile salt aggregates of different head groups and hydrophobic skeletons: a photophysical study to probe bile salts as multisite drug carriers

The entrapment of neutral and cationic species of an anticancer drug, namely ellipticine and their dynamic features in different bile salt aggregates have been investigated for the first time using steady state and time-resolved fluorescence spectroscopy. Because ellipticine exists in various prototropic forms under physiological conditions, we performed comparative photophysical and dynamical studies on these prototropic species in different bile salts varying in their head groups and hydrophobic skeletons. We found that the initial interaction between ellipticine and bile salts is governed by the electrostatic forces where cationic ellipticine is anchored to the head groups of bile salts. Bile salts having conjugated head groups are better candidates to bind with the cationic species than those having the non-conjugated ones. The fact implies that binding of cationic species to different bile salts depends on the pK(a) of the corresponding bile acids. The hydrophobic interaction dominates at higher concentrations of bile salts due to formation of aggregates and results in entrapment of neutral ellipticine molecules according to their hydrophobicity indices. Thus bile salts act as multisite drug carriers. The rotational relaxation parameters of cationic ellipticine were found to be dependent on head groups and the number of hydroxyl groups on the hydrophilic surface of bile salts. Cationic ellipticine exhibits a faster rotational relaxation in the tri-hydroxy bile salt aggregates than in di-hydroxy bile salts. We interpreted this observation from the fact that tri-hydroxy bile salts hold a higher number of water molecules in their hydrophilic surface offering a less viscous environment for ellipticine compared to di-hydroxy bile salts. Surprisingly, the neutral ellipticine molecules display almost the same rotational relaxation in all the bile salts. The observation indicates that after intercalation inside the hydrophobic pocket, neutral ellipticine molecules experience similar confinement in all the bile salts.

Excited state proton transfer dynamics of an eminent anticancer drug, ellipticine, in octyl glucoside micelle

Photophysics and proton transfer dynamics of an eminent anticancer drug, ellipticine (EPT), have been investigated inside a biocompatible octyl-β-D-glucoside (OBG) micellar medium using steady state and time-resolved fluorescence spectroscopic techniques. EPT exists as protonated form in aqueous solution of pH 7. When EPT molecules are encapsulated in OBG micelles, protonated form is converted to neutral form in the ground state due to the hydrophobic effect of the micellar environment. Interestingly, steady state fluorescence results indicate the existence of both neutral and protonated forms of EPT in the excited state, even though neutral molecules are selectively excited, and it is attributed to the conversion of neutral to protonated form of EPT by the excited state proton transfer (ESPT) process. A clear isoemissive point in the time-resolved area normalized emission spectra (TRANES) further supports the excited state conversion of neutral to protonated form of EPT. Notably, this kind of proton transfer dynamics is not observed in other conventional micelles, such as, SDS, Triton-X and CTAB. Therefore, the observed ESPT dynamics is believed to be an outcome of combined effects of the local dielectric constant felt by EPT and the local proton concentration at the OBG micellar surface.

Controlled release of a sparingly water-soluble anticancer drug through pH-responsive functionalized gold-nanoparticle-decorated liposomes

The binding and detachment of carboxyl-modified gold nanoparticles from liposomes is used for controlled drug delivery. This study reveals that the binding and detachment of nanoparticles from liposomes depends on the degree of hydration of the liposomes. Liposomes with a lower hydration level undergo stronger electrostatic interactions with negatively charged gold nanoparticles, thus leading to a slower detachment of the carboxyl-modified gold nanoparticles under gastric conditions. Therefore, under gastric conditions, gold-nanoparticle-decorated dipalmitoylphosphatidylcholine (DPPC) liposomes exhibit an at least ten-times-slower drug release compared to gold-nanoparticle-decorated 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) liposomes, although both liposomes in the bare state fail to pursue controlled release. Our study also reveals that one can modulate the drug-release rate by simply varying the concentration of nanoparticles. This study highlights a novel strategy for the controlled release of drug molecules from liposomes.

Interaction of different prototropic species of an anticancer drug ellipticine with HSA and IgG proteins: multispectroscopic and molecular modeling studies

Studies on interactions between an anticancer alkaloid, ellipticine, and various carrier proteins in blood serum show tangible results to gain insight into the solubility and transport of the drug under physiological conditions.

Molecular-level pictures of the phase transitions of saturated and unsaturated phospholipid binary mixtures

Saturated and unsaturated lipids change nonsynchronously upon heating-induced phase transitions.

pH responsive translocation of an anticancer drug between cyclodextrin and DNA

Herein, the pH triggered translocation of EPT in between γ-cyclodextrin and DNA is monitored using fluorescence switch of the drug.

Modulation of the aggregation properties of sodium deoxycholate in presence of hydrophilic imidazolium based ionic liquid: water dynamics study to probe the structural alteration of the aggregates

In this article, we have investigated the effect of hydrophilic 1-butyl-3-methylimidazolium tetrafluoroborate on the aggregation properties of sodium deoxycholate (NaDC).

Interaction of human serum albumin with liposomes of saturated and unsaturated lipids with different phase transition temperatures: a spectroscopic investigation by membrane probe PRODAN

The interaction of human serum albumin (HSA) with liposomes made of saturated and unsaturated phosphocholines has been studied using circular dichroism (CD), steady state and time resolved fluorescence spectroscopic techniques.

Photophysical behavior of 8-anilino-1-naphthalenesulfonate in vesicles of pulmonary surfactant dipalmitoylphosphatidylcholine (DPPC) and its sensitivity toward the bile salt-vesicle interaction

The photophysical behavior of 8-anilino-1-naphthalenesulphonate (ANS) in vesicles of dipalmitoylphosphatidylcholine (DPPC), a pulmonary surfactant, has been carried out in a detailed manner. ANS shows notable variations in fluorescence intensity, lifetime, and anisotropy parameters as it gets into the vesicle. It was found that ANS partitions well into the DPPC bilayer membrane with an estimated partition coefficient of ~2.0 × 10(5). Among the various fluorescence parameters of ANS, fluorescence anisotropy was found to be most responsive to the temperature induced phase change of the bilayer membrane. These interesting fluorescence parameters of ANS were then used to study the hydration of lipid bilayer membrane by submicellar concentration of bile salts. From the steady-state fluorescence intensity and dynamic fluorescence lifetime analyses it is clear that ANS is able to probe the submicellar concentration (≤1 mM) of bile salt induced hydration of lipid bilayer membrane that accompanies expulsion of ANS from the bilayer to the aqueous bulk phase. Lower-temperature shift in the phase transition of DPPC bilayer indicates that fluorescence anisotropy of ANS is sensitive enough to the bile salt induced perturbation in the packed acyl chains of DPPC bilayer and modification in the membrane fluidity. In presence of sodium deoxycholate (NaDC) and sodium cholate (NaC) in DPPC vesicles, ANS experiences restriction in rotational mobility which is evident from the variation in steady-state fluorescence anisotropy and fluorescence anisotropy decay parameters.