Conventional cancer chemotherapy presents several bottlenecks, such as lack of specificity that impacts healthy tissues, rapid drug metabolism, and both intrinsic/acquired drug resistances varying in patient status, which altogether lead to reduction of efficacy. To overcome these issues and improve efficacy, combination with novel nanotechnology approaches-cancer nanomedicine-in the areas of imaging, diagnosis, and drug delivery are being proposed. These developments have been focused upon the preparation and application of nanoparticles for cancer therapy. Gold nanoparticle (AuNP) applications have been projected for improved imaging, diagnosis, and therapy, due to their exquisite physicochemical and optical properties showing potential applications as drug/gene carriers, photothermal and contrast agents. All these features may potentiate selective drug delivery, thus improving efficacy and reducing side effects. In this chapter, we shall discuss applications of nanoparticles with focus on AuNPs as efficient targeted (drug) delivery systems in cancer therapy.

Multifunctionalized gold nanobeacons (Au-nanobeacon) combine, in a single and unique platform, targeting, detection and silencing providing an effective impact in clinics boosting cancer theranostics. Here, we describe a nano-integrated platform based on Au-nanobeacons able to detect and inhibit gene expression specifically in cancer cells. The surfaces of gold nanoparticles (AuNPs) are functionalized with targeting peptides to enhance tumor cell recognition and uptake, and with fluorescently labeled antisense DNA hairpin oligonucleotides to detect AuNPs. These oligonucleotides, upon recognition and hybridization to the target, open their structure resulting in separating apart the dye and the quencher allowing the fluorophore to emit light and to monitor the intracellular interactions of AuNPs with the target and the specific silencing of gene expression. This strategy allows inhibiting KRAS gene expression in colorectal carcinoma cell lines with no relevant toxicity for healthy fibroblasts. Importantly, this nano-integrated platform can be easily adapted to hybridize with any specific target thus providing real benefits for the diagnosis and treatment of cancer.

Nanotechnology has led to the development of new and improved materials, and particular emphasis has been directed toward nanoparticles and their multiple bio-applications. Nanoparticles exhibit size-, shape-, and compositiondependent properties, e.g., surface plasmon resonance and photothermal properties, which may potentially enhance laser desorption/ionization systems for mass spectrometry-based analysis of biomolecules. Also, nanoparticles possess high surface to volume ratio that can be easily derivatized with a wide range of ligands with different functional groups. Surface modification makes nanoparticles advantageous for sample preparation procedures prior to detection by mass spectrometry. Moreover, it allows the synthesis of affinity probes, which promotes interactions between nanoparticles and analytes, greatly enhancing the ionization efficiency. This chapter provides a comprehensive discussion on the use of nanoparticles for mass spectrometry-related applications, from sample preparation methodologies to ionization surfaces. Applications will focus on nanoparticle size, composition, and functionalization, as a comparative point of view on optimal characteristics toward maximization of bioassay efficiency.

Nanotechnology based diagnostics has provided improved tools for pathogen detection and sensitive and specific characterization of antibiotic resistance signatures. Tuberculosis (TB) is caused by members of the Mycobacterium tuberculosis Complex (MTBC) and, according to the World Health Organization, is one of the most serious infectious diseases in the world. Recent advances in molecular diagnostics of TB have improved both the detection time and sensitivity but they still require specialized technical personnel and cumbersome laboratory equipment. Diagnostics at point-of-need is crucial to TB control as it may provide rapid identification of pathogen together with the resistance profile of TB strains, originated from single nucleotide polymorphisms (SNPs) in different loci , allowing for a more accurate indication of the adequate therapy.Gold nanoparticles have been widely used in molecular diagnostics platforms. Here, we describe the use of gold nanoprobes (oligonucleotide functionalized gold nanoparticles) to be used in a non-crosslinking colorimetric method for the direct detection of specific DNA targets. Due to the remarkable optical properties of gold nanoparticles, this detection system provides colorimetric detection of the pathogen together with the potential of identification of several single nucleotide polymorphisms (SNPs) involved in TB resistance to antibiotics. For point-of-need use, we adapted this strategy to a low-cost mobile scheme using a paper based revelation platform and where the spectral signature is transposed to RGB data via a smartphone device. This way, identification of pathogen and characterization of resistance signatures is achieved at point-of-need.

Nanotechnology provides new tools for gene expression analysis that allow for sensitive and specific characterization of prognostic signatures related to cancer. Cancer is a multigenic complex disease where multiple gene loci contribute to the phenotype. The ability to simultaneously monitor differential expression originating from each locus allows for a more accurate indication of degree of cancerous activity than either locus alone. Metal nanoparticles have been widely used as labels for in vitro identification and quantification of target sequences. Here we describe the synthesis of nanoparticles with different noble metal compositions in an alloy format that are then functionalized with thiol-modified ssDNA (nanoprobes). We also show how to use such nanoprobes in a non-cross-linking colorimetric method for the direct detection and quantification of specific mRNA targets, without the need for enzymatic amplification or reverse transcription steps. The different metals in the alloy provide for distinct absorption spectra due to their characteristic plasmon resonance peaks. The color multiplexing allows for simultaneous identification of several different mRNA targets involved in cancer development. Comparison of the absorption spectra of the nanoprobes mixtures taken before and after induced aggregation of metal nanoparticles allows to both identify and quantify each mRNA target. We describe the use of gold and gold:silver-alloy nanoprobes for the development of the non-cross-linking method to detect a specific BCR-ABL fusion gene (e.g., e1a2 and e14a2) mRNA target associated with chronic myeloid leukemia (CML) using 10 ng μL -1 of unamplified total human RNA. This simple methodology takes less than 50 min to complete after total RNA extraction with comparable specificity and sensitivity to the more commonly used methods.