INTRODUCTION

For more than a decade, nanometer-sized gold nanoparticles (GNPs) have attracted considerable attention not only because of their size- and shape-dependent optical and electronic properties but also due to their latent uses in thermal imaging, catalysis, scattering analysis, photoelectronic devices, biomedical diagnostics, and other related fields.1–3


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GNPs offer important new possibilities in cancer diagnosis and therapy4 and can be used in the imaging5,6 of tumors in their primary and secondary locations, as delivery agents for antitumor drugs, and for nonaggressive amputation treatments.

The conveyance of the NPs to the tumor is a multistage technique.7 Systemically controlled NPs with tumor-binding ligands can accumulate in the cancer cell due to the additional disordered vasculature relative to noncontaminated tissue.6,7

Cancer is challenging to treat, so active diagnosis approaches in the early phases of cancer are life threatening. In this respect, imaging has become an essential instrument in cancer medical trials and therapeutic replication.8

Fluorescent bioimaging is also of extreme importance for visualizing the manifestation and movement of specific particles, cells, and biological processes that affect the performance of tumors and/or their reaction to therapeutic medications.9

Therefore, an extensive series of fluorescent modules has been explored in in vitro bioimaging studies, including the biomarking of cancer tissues,10 angiogenic vasculature, and sentry lymph nodes.11

In this respect, numerous nanomaterials such as quantum dots, noble metal NPs, upconverted NPs, and new fusion nanocomposites of reduced graphene oxide and GNPs have great potential for highly sensitive optical imaging of cancer in both in vitro and in vivo experiments.

From this viewpoint, GNPs are innovative biocompatible nanoprobes, offering surfaces and cores that possess physicochemical properties (eg, optical chirality,12,13 fluorescence,14 near-infrared photoluminescence,15 and ferromagnetism16) that offer novel openings for clinical diagnostics. As such, these tools will certainly play a vital part in the initial analysis and responsive recognition of tumors.

The multifunctional behavior of NPs offers exclusive benefits for the tumor-specific transfer of imaging and medicinal agents.17 Monoclonal antibodies with substantially assorted structures and properties are economical to produce and have great feasibility as a class of tracking moieties.18

One of the most broadly studied monoclonal antibodies used as a targeting moiety for the distribution of agents is herceptin. Herceptin is a water-soluble antibody that binds to the human epidermal growth factor receptor 2 (HER2) found on the membrane of SK-BR3 cells.

In this study, SK-BR3 cells were attacked with herceptin-conjugated GNPs (GNP–Her) for tumor treatment and diagnosis.

Mercaptosuccinic acid (MSA)–immobilized GNPs were prepared by citrate reduction, followed by the coupling reaction of GNP with acid-terminated MSA. Herceptin was then immobilized on the surface of GNP (GNP–Her) to enrich the anticancer effects of chemotherapeutic agents.19–22

The surface properties of GNP and GNP–Her were characterized by Fourier transform infrared (FT-IR) spectroscopy, ultraviolet–visible (UV–vis) spectrometry, dynamic light scattering (DLS), and transmission electron microscopy (TEM).

To estimate the cell compatibility and cytotoxicity of the GNPs and GNP–Her conjugates, human breast cancer cells (SK-BR3) were cultured in the presence of GNPs. The intracellular uptake of GNP–Her into the cells was also observed by confocal laser scanning microscopy (CLSM) and inductively coupled plasma mass spectrometry (ICP–MS).23

MATERIALS AND METHODS

Auric chloride (HAuCl4), sodium citrate (Na3C6H5O7), MSA, and herceptin were purchased from Hoffman-La Roche Ltd (Basel, Switzerland). Cell culture reagents, fetal bovine serum, Dulbecco’s Modified Eagle’s Medium (DMEM), penicillin–streptomycin mix, trypsin–ethylene diamine tetraacetic acid (EDTA) solution, Dulbecco’s phosphate-buffered saline (PBS), and cell viability staining reagents were provided by Gibco BRL (Thermo Fisher Scientific, Waltham, MA, USA), and the cells (SK-BR3 and FB) were purchased from the Korean Cell Line Bank.