Development of Folate-Thioglycolate-Gold Nanoconjugates by Using Citric Acid-PEG Branched Polymer for Inhibition of MCF‑7 Cancer Cell Proliferation

Development of folate (FA)-functionalized gold nanoparticles (AuNPs) has greatly increased in recent years due to their potential in cancer treatment. As surface functionalization of polymer-free AuNPs with thiol groups could result in agglomeration and precipitation, AuNPs should be stabilized with an efficient polymer. In this study, citric acid-PEG branched polymer (CPEG) acted as a reducing as well as stabilizing agent in the synthesis of AuNPs. The thiol group of thioglycolic acid (TGA) attached to CPEG-stabilized AuNPs and interacted with the free carboxylic acid group on the surface of TGA-AuNP nanoconjugates. Stable TGA-AuNP nanoconjugates were obtained only with CPEG-stabilized AuNPs and not with citrate-stabilized AuNPs. The carboxylic acid group on the surface of AuNPs was used to attach FA via an EDC/NHS coupling reaction to obtain FA-TGA-AuNP nanoconjugates. In vitro cytotoxicity studies indicated that FA-TGA-AuNPs were not toxic to normal cells up to a concentration of 200 μg/mL. However, FA-TGA-AuNP nanoconjugates effectively inhibited proliferation of MCF-7 cancer cells at a low concentration of 25 μg/mL after 3 days of incubation. The anticancer activity of FA-TGA-AuNPs was enhanced by incorporating the anticancer drug 5-fluorouracil into the nanoconjugates, which exhibited sustained drug release up to 5 days. Hence, the developed biocompatible FA-TGA-AuNPs could be used for specific killing of breast cancer cells

Biomaterial-Mediated Exogenous Facile Coating of Natural Killer Cells for Enhancing Anticancer Efficacy toward Hepatocellular Carcinoma

Natural killer (NK) cells exhibit a good therapeutic efficacy against various malignant cancer cells. However, the therapeutic efficacy of plain NK cells is relatively low due to inadequate selectivity for cancer cells. Therefore, to enhance the targeting selectivity and anticancer efficacy of NK cells, we have rationally designed a biomaterial-mediated ex vivo surface engineering technique for the membrane decoration of cancer recognition ligands onto NK cells. Our designed lipid conjugate biomaterial contains three major functional moieties: (1) 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) lipid for cell membrane anchoring, (2) polyethylene glycol for intracellular penetration blocker, and (3) lactobionic acid (LBA) for cancer recognition. The biomaterial was successfully applied to NK cell surfaces (LBA-NK) to enhance recognition and anticancer functionalities, especially toward asialoglycoprotein receptor (ASGPR)-overexpressing hepatocellular carcinoma. Highly efficient and homogeneous NK cell surface editing was achieved with a simple coating process while maintaining intrinsic properties of NK cells. LBA-NK cells showed potential ASGPR-mediated tumor cell binding (through LBA-ASGPR interaction) and thereby significantly augmented anticancer efficacies against HepG2 liver cancer cells. Thus, LBA-NK cells can be a novel engineering strategy for the treatment of liver cancers via facilitated immune synapse interactions in comparison with currently available cell therapies

Cytotoxicity of Gallium–Indium Liquid Metal in an Aqueous Environment

Eutectic gallium–indium alloy (EGaIn) liquid metal is highly conductive, moldable, and extremely deformable and has attracted significant attention for many applications, ranging from stretchable electronics to drug delivery. Even though EGaIn liquid metal is generally known to have low toxicity, the toxicity of the metal, rather than a salt form of Ga or In, has not been systematically studied yet. In this paper, we investigate the time-dependent concentration of the ions released from EGaIn liquid metal in an aqueous environment and their cytotoxicity to human cells. It is observed that only the Ga ion is dominantly released from EGaIn when no external agitation is applied, whereas the concentration of the In ion drastically increases with sonication. The cytotoxicity study reveals that all human cells tested are viable in the growth media with naturally released EGaIn ions, but the cytotoxicity becomes significant with sonication-induced EGaIn releasates. On the basis of the comparative study with other representative toxic elements, that is, Hg and Cd, it could be concluded that EGaIn is reasonably safe to use in an aqueous environment; however, it should be cautiously handled when any mechanical agitation is applied

Effects of Immobilized BMP‑2 and Nanofiber Morphology on In Vitro Osteogenic Differentiation of hMSCs and In Vivo Collagen Assembly of Regenerated Bone

Engineering bone tissue is particularly challenging because of the distinctive structural features of bone within a complex biochemical environment. In the present study, we fabricated poly­(l-lactic acid) (PLLA) electrospun nanofibers with random and aligned morphology immobilized with bone morphogenic protein-2 (BMP-2) and investigated how these signals modulate (1) in vitro osteogenic differentiation of human mesenchymal stem cells (hMSCs) and (2) in vivo bone growth rate, mechanical properties, and collagen assembly of newly formed bone. The orientation of adherent cells followed the underlying nanofiber morphology; however, nanofiber alignment did not show any difference in alkaline phosphate activity or in calcium mineralization of hMSCs after 14 days of in vitro culture in osteogenic differentiation media. In vivo bone regeneration was significantly higher in the nanofiber implanted groups (approximately 65–79%) as compared to the defect-only group (11.8 ± 0.2%), while no significant difference in bone regeneration was observed between random and aligned groups. However, nanoindentation studies of regenerated bone revealed Young’s modulus and contact hardness with anisotropic feature for aligned group as compared to random group. More importantly, structural analysis of collagen at de novo bone showed the ability of nanofiber morphology to guide collagen deposition. SEM and TEM images revealed regular, highly ordered collagen assemblies on aligned nanofibers as compared to random fibers, which showed irregular, randomly organized collagen deposition. Taken together, we conclude that nanofibers in the presence of osteoinductive signals are a potent tool for bone regeneration, and nanofiber alignment can be used for engineering bone tissues with structurally assembled collagen fibers with defined direction