A Gold-Nanoparticle-Based Real-Time Colorimetric Screening Method for Endonuclease Activity and Inhibition

Targeted delivery of gemcitabine to pancreatic adenocarcinoma using cetuximab as a targeting agent

One of the key challenges in anticancer therapy is the toxicity and poor bioavailability of the anticancer drugs. Nanotechnology can play a pivotal role by delivering drugs in a targeted fashion to the malignant cells that will reduce the systemic toxicity of the anticancer drug. In this report, we show a stepwise development of a nanoparticle-based targeted delivery system for in vitro and in vivo therapeutic application in pancreatic cancer. In the first part of the study, we have shown the fabrication and characterization of the delivery system containing gold nanoparticle as a delivery vehicle, cetuximab as a targeting agent, and gemcitabine as an anticancer drug for in vitro application. Nanoconjugate was first characterized physico-chemically. In vitro targeting efficacy, tested against three pancreatic cancer cell lines (PANC-1, AsPC-1, and MIA Paca2) with variable epidermal growth factor receptor (EGFR) expression, showed that gold uptake correlated with EGFR expression. In the second part, we showed the in vivo therapeutic efficacy of the targeted delivery system. Administration of this targeted delivery system resulted in significant inhibition of pancreatic tumor cell proliferation in vitro and orthotopic pancreatic tumor growth in vivo. Tumor progression was monitored noninvasively by measuring bioluminescence of the implanted tumor cells. Pharmacokinetic experiments along with the quantitation of gold both in vitro and in vivo further confirmed that the inhibition of tumor growth was due to targeted delivery. This strategy could be used as a generalized approach for the treatment of a variety of cancers characterized by overexpression of EGFR.

Ultrasensitive optical biodiagnostic methods using metallic nanoparticles

Dramatic progress has been made over the recent decade in the applications of metallic nanoparticles in the field of biomolecule detection. The useful physical and chemical properties (e.g., availability of various synthetic methods of size- and shape-controlled nanoparticles, size- and shape-dependent optical properties, availability of various surface chemistries and biocompatibility) of metallic nanoparticles have brought development to the ultrasensitive detection of biomolecules at the attomolar level and this sensitivity enables the diagnosis of otherwise undetectable biomarkers of many fatal diseases, including Alzheimer’s disease. Furthermore, coupled with the strong physical properties and biocompatible nature of gold nanoparticles in in vivo conditions, the scope of applications for these particles have been broadened into the field of in vivo imaging, such as X-ray contrasting agents, and also cellular tracking. Here, we review synthetic methods and optical properties of metallic nanoparticles and their use in ultrasensitive, in vitro and in vivo biodiagnostic methods.

Gold nanoparticles for the development of clinical diagnosis methods

The impact of advances in nanotechnology is particularly relevant in biodiagnostics, where nanoparticle-based assays have been developed for specific detection of bioanalytes of clinical interest. Gold nanoparticles show easily tuned physical properties, including unique optical properties, robustness, and high surface areas, making them ideal candidates for developing biomarker platforms. Modulation of these physicochemical properties can be easily achieved by adequate synthetic strategies and give gold nanoparticles advantages over conventional detection methods currently used in clinical diagnostics. The surface of gold nanoparticles can be tailored by ligand functionalization to selectively bind biomarkers. Thiol-linking of DNA and chemical functionalization of gold nanoparticles for specific protein/antibody binding are the most common approaches. Simple and inexpensive methods based on these bio-nanoprobes were initially applied for detection of specific DNA sequences and are presently being expanded to clinical diagnosis. Figure Colorimetric DNA/RNA detection using salt induced aggregation of AuNP-DNA nanoprobes.

Simple and rapid colorimetric enzyme sensing assays using non-crosslinking gold nanoparticle aggregation

Non-crosslinking gold nanoparticle (AuNP) aggregation induced by the loss (or screen) of surface charges is applied for enzymatic activity sensing and potentially inhibitor screening.