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The aim of this study was to investigate the impact of different chain length fatty acids on physicochemical properties and cancer targeting of fattigation-platform nanoparticles (NPs). Two different types of fatty acids (short chain, 2-hydroxybutyric acid, C4; long chain, oleic acid, C18:1) were successfully conjugated to human serum albumin (HSA) via simple 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) coupling reaction. These conjugates readily formed HSA-C4 and HSA-C18:1 NPs which showed good stability in serum and desirable biocompatibility with normal cell line (HEK293T). Doxorubicin hydrochloride (DOX) was efficiently loaded into NPs by incubation process via electrostatic interaction. The structure, morphology, and texture of DOX-loaded NPs were characterized by Transmission electron microscopy (TEM) equipped with Energy-dispersive X-ray spectroscopy (EDS). The initial burst release of DOX-loaded NPs was controlled by the presence and chain length of fatty acids. In vitro cytotoxicity studies with three cancer cell lines (A549, HT-29, and PANC-1) suggested that fattigation-platform NPs have distinctive cytotoxic effects compared to Doxil®. Confocal microscopy and flow cytometry exhibited that the cellular uptake of DOX-loaded NPs was varied by the different chain lengths of fatty acids. It was evident that the chain length of fatty acids in the fattigation-platform NPs could play a vital role in varying physicochemical properties and cancer cell targeting of NPs.

Albumin is the most abundant protein in blood, and is the most frequently identified protein in the protein corona of nanoparticles (NPs). Thus, albumin plays an important role in modulating NPs' physicochemical properties and bioavailability. In this study, the effect of bovine serum albumin (BSA) on gelatin-oleic nanoparticles' (GONs) physicochemical properties and cellular uptake were evaluated. Coumarin-6 was used as indicator to track the cellular uptake of GONs. The binding of BSA onto the GON surface increased the size, slightly reduced the negative net charge of the GON, and improved GON stability. The presence of BSA in cell culture media reduced the cellular uptake of BSA-uncoated GONs on human embryonic kidney cells 293 (HEK 293) and human adenocarcinoma alveolar basal epithelial cells (A549) in the media without FBS addition. Pre-coated BSA corona decreased cellular uptake of GONs in A549 cells in the media, with and without supplemented with 10% fetal bovine serum (FBS) but drastically increased cellular uptake on HEK 293 cells. BSA could be used to modulate protein corona as an endogenous ligand in NP design simply by mixing or incubating BSA with NPs before in vivo administration to inhibit or induce cellular uptake in specific cell types.

The aims of this work were to design pH-independent controlled release (CR) tablet containing nanonizing solid dispersion (SD) adsorbed on hydrophilic silica (Aeroperl® 300/30). Valsartan (VAL) was chosen to simultaneously modulate solubility and release rate due to its poor water solubility in low pH condition and short elimination half-life. Based on extensive equilibrium solubility and compatibility studies, poloxamer 407 was selected as a SD carrier. The melted mixtures of drug and poloxamer 407 were adsorbed onto hydrophilic fumed silica (Aeroperl® 300/30). Ternary SD system changed crystalline drug into an amorphous state and had intermolecular hydrogen bonding as confirmed by FT-IR with poloxamer 407. The dissolution rate of SD system was markedly enhanced as compared with pure VAL or commercial Diovan® tablet in simulated gastric fluid (pH 1.2). Interestingly, the particle size of SD system was gradually nanonized for 2 hr, ranging from 600 nm to 150 nm during dissolution process. The SD-loaded CR (SD-CR) tablets using hydroxypropylmethylcellulose (HPMC 4000) showed pH-independent zero-order release and good stability at accelerated conditions for six months. The SD-CR tablet showed minimized inter-subject variation of maximum plasma concentration as compared with commercial Diovan® tablets in healthy human volunteers.

The principles of bioorthogonal click chemistry and metabolic glycoengineering were applied to produce targeted anti-cancer drug delivery via fattigation-platform-based gelatin-oleic nanoparticles. A sialic acid precursor (Ac4ManNAz) was introduced to the cell surface. Gelatin and oleic acid were conjugated by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) chemistry with the subsequent covalent attachment of dibenzocyclooctyne (DBCO) in a click reaction on the cell surface. The physicochemical properties, drug release, in vitro cytotoxicity, and cellular uptake of DBCO-conjugated gelatin oleic nanoparticles (GON-DBCO; particle size, ∼240 nm; zeta potential, 6 mV) were evaluated. Doxorubicin (DOX) was used as a model drug and compared with the reference product, Caelyx®. A549 and MCF-7 cell lines were used for the in vitro studies. GON-DBCO showed high DOX loading and encapsulation efficiencies. In A549 cells, the IC50 value for GON-DBCO-DOX (1.29 µg/ml) was six times lower than that of Caelyx® (10.54 µg/ml); in MCF-7 cells, the IC50 values were 1.78 µg/ml and 2.84 µg/ml, respectively. Confocal microscopy confirmed the click reaction between GON-DBCO and Ac4ManNAz on the cell surface. Flow cytometry data revealed that the intracellular uptake of GON-DBCO-DOX was approximately two times greater than that of GON-DOX and Caelyx®. Thus, the newly designed GON-DBCO-DOX provided a safe and efficient drug delivery system to actively target the anticancer agents.

The concept of click chemistry (CC), first introduced by K.B. Sharpless, has been widely adopted for use in drug discovery, novel drug delivery systems (DDS), polymer chemistry, and material sciences. In this review, we outline novel aspects of CC related to drug discovery and drug delivery, with a brief overview of molecular mechanisms underlying each click reaction commonly used by researchers, and the main patents that paved the way for further diverse medicinal applications. We also describe recent progress in drug discovery and polymeric and carbon material-based drug delivery for potential pharmaceutical applications and advancements based on the CC approach, and discuss some intrinsic limitations of this popular conjugation reaction. The use of CC is likely to significantly advance drug discovery and bioconjugation development.

A major hurdle in cancer treatment is the precise targeting of drugs to the cancer site. As many cancer cells overexpress the transferrin receptor (TfR), the transferrin (Tf)-TfR interaction is widely exploited to target cancer cells. In this study, novel amphiphilic apo-Tf stearic acid (TfS) conjugates were prepared and characterized by Fourier transform infrared (FTIR) spectroscopy, matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry, and trinitrobenzenesulfonic acid (TNBS) assay. The prepared TfS conjugates were readily self-assembled in water to form nanoparticles (NPs), consisting of TfS as a core of NPs, whose sizes and zeta potentials were determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and a particle size analyzer. Hydrophilic water-soluble doxorubicin (DOX) was chosen as a model drug. DOX-loaded TfS NPs (NP+DOX), prepared by the adsorption of DOX on the NP surface via the incubation method, were analyzed for their cell targeting and killing efficiencies in TfR-overexpressing A549 and HCT116 cell lines by MTT assay, confocal microscopy, and fluorescence assisted cell sorting (flow cytometry). The data showed that NP+DOX exhibited improved cancer cell targeting and killing properties compared to that reported for free DOX. Further, the cytotoxic efficiency of NP+DOX was comparable to that of PEGylated liposomal product, Doxil®, while its cellular uptake was higher than that of Doxil®. Thus, this novel receptor-based TfS NP drug delivery system has great potential to target TfR-overexpressing cancer cells without off-target effects.

In this study, apotransferrin (Tf)-stearic acid conjugate was newly synthesized via “fattigation method” to form self-assembled nanoparticles (NPs) containing a hydrophobic model drug, paclitaxel (PAC). Then, physicochemical properties and cellular behaviors such as transferrin receptor-driven targeting and cytotoxic efficiencies were evaluated. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies showed that the NPs had spherical shape and smooth surface. The particle size of PAC-loaded NPs was 326.97 ± 2.03 nm with a loading and encapsulation efficiency of 7.94 ± 1.60% (w/w) and 71.10 ± 4.12% (w/w), respectively. In comparison to free PAC, PAC-loaded NPs showed a 7-fold reduction in the LC50 value in breast carcinoma cells (MCF-7), which indicated an increase in cytotoxicity owing to the effective targeting of cells. This observation was confirmed via confocal microscopy images that showed that transferrin receptor blocking inhibited NP uptake. This was further confirmed via flow cytometry data which showed the time-dependent uptake of NPs and their inhibition by transferrin receptor blockage. The results of this study reveal the advantages of NP-based drug delivery systems consisting of Tf as a core of NP for the receptor-driven targeting and subsequent killing of cancer cells.

This study was aimed at characterizing superparamagnetic nanoparticles surface-functionalized with gelatin-oleic acid (GOAS-MNPs) and loaded with paclitaxel by assessing the pharmacokinetics and biodistribution of paclitaxel in tissues and the in vivo efficacy of antitumor activity after the administration of the drug. Initially, instrumental analysis was performed to examine the particle size distribution, surface charge, and morphology of the paclitaxel-loaded GOAS-MNPs. Furthermore, we evaluated their magnetic properties and performed T2-weighted magnetic resonance imaging (MRI) on cells. We intravenously administered Taxol® and paclitaxel-loaded GOAS-MNPs and compared the pharmacokinetics, biodistribution, and antitumor efficacies of the two formulations. Determination of the pharmacokinetics and the biodistribution of paclitaxel-loaded NPs showed that this formulation increased the systemic circulation time of paclitaxel and regulated its transport to tissues. The in vivo antitumor efficacy of the paclitaxel-loaded NPs was better than that of Taxol® at the same dose. Furthermore, the paclitaxel-loaded GOAS-MNPs were found to be effective as contrast agents for enhanced MRI in cancer cells. Thus, GOAS-MNPs could be an effective diagnostic system for cancer and for the delivery of paclitaxel with better therapeutic effects and a significant reduction in toxicity.