Glioblastoma is associated with abnormal proliferation of the glial cells in the brain and has the highest mortality rate among all types of cancers. Among the few drugs, including carmustine, lomustine, everolimus, bevacizumab, and temozolomide (TMZ), which were approved for treating glioblastoma, TMZ is considered a first line choice. TMZ attains 100 % plasma bioavailability when administered in the form of oral capsules and intravenous infusion. Despite its high permeability through the blood-brain barrier, only 20-30 % brain bioavailability is achieved as TMZ undergoes non-enzymatic modification at plasma pH. The resulting active metabolites of TMZ cannot cross the blood-brain barrier due to their hydrophilic nature. The short half-life of TMZ limits its therapeutic efficacy. These limitations of conventional therapies can be tackled with nanomedicine [1], [2].

The pharmacokinetics and biodistribution of the drug to the target site can be altered by designing a suitable dosage form. Numerous nanocarriers like solid lipid nanocarriers, polymeric nanoparticles, and nanostructured lipid carriers have been investigated for TMZ [3], [4], [5]. The nanocarriers protect the drug from plasma pH, delay the conversion rate, modify the drug release rate, and extend the plasma circulation time. The nanocarrier size, surface charge, morphology, and content of the developed formulation significantly influence various pharmacokinetic parameters of a drug administered intravenously. Nanocarriers with particle size between 80-120 nm are known to show longer plasma circulation time. Since the invention of Doxil®, it has been revealed that PEGylation of nanocarriers can prevent macrophage uptake and prolong the plasma circulation time [6], [7].

Lipid-based nanocarriers have become popular due to their biocompatible nature. Liposomes are one of the most clinically successful nanocarriers. These are phospholipid vesicles enclosing an aqueous core [8], [9]. Advanced research led to the discovery of other vesicular structures like lyotropic liquid crystals (LLCs). This mesophase contains properties of a crystal and liquid simultaneously. TMZ is amphiphilic in nature. Both these self-assembled nanocarrier structures possess hydrophilic as well as hydrophobic regions, making them suitable for entrapping hydrophilic, lipophilic, and amphiphilic drugs. TMZ has been reported to leach out easily from nanocarriers due to its more affinity towards water resulting in low entrapment efficiency. LLCs consist of a honeycomb like structure, wherein, TMZ has to cross multiple layers before reaching the outside media. This protects the drug for longer period and provides prolonged release [10], [11]. In a study, liquid crystalline nanoparticles entrapping pemetrexed and resveratrol with particle size 173 ± 0.26 nm were investigated. The intravenous delivery of these nanocarriers was found to be beneficial in lung cancer [12]. Another study investigated aloe-emodin-loaded PEGylated liquid crystalline nanoparticles for breast cancer. The nanocarriers obtained with a particle size of 190 nm demonstrated a 5.4-fold increase in the half-life of aloe-emodin on intraperitoneal administration [13]. The existing literature revealed the suitability of liposomes and lyotropic liquid crystals for the delivery of TMZ.

In our previous studies, we investigated the impact of different formulation and process variables on the characteristics of liposomes and LLCs in detail [14], [15]. In the present study, the optimized formulations were further studied for cytotoxicity, cell uptake, pharmacokinetics, and biodistribution to validate the potential of these nanocarriers in the effective cure of glioblastoma. Most of the nanocarriers investigated for TMZ before had particle sizes above 150 nm. We targeted liposomes and lyotropic liquid crystals with particle size between 80-120 nm to attain a longer plasma circulation time. Also, the nanocarriers were investigated using preparation methods which involve minimum number of steps, are highly reproducible and industrial feasible.