Nanoparticles can be applied to a wide variety of the multidisciplinary fields including nanomedicine, nanofood, and nanocosmetics. Among various engineered nanomaterials, inorganic nanoparticles have attracted a great deal of interest as efficient delivery nanocarriers for drugs, gene molecules, biomedical products, nutrients, and functional molecules. The most elementary term, nanomedicine, represents nanodevices used to diagnose and cure diseases at nanoscale with site-specific therapeutic action and minimized side effects. One of the more advanced and defined nanomedicines is the nanomaterial -based drug delivery system, which is designed to improve the pharmacological and therapeutic efficacy of drugs.

 The most extensively commercialized branch of nanotechnology is nanocosmetics. Nano -ingredients such as metal oxide nanoparticles and carbon fullerenes are used not only to protect active substance, but also to enhance the skin penetrating efficiency. Recently, the impacts of nanotechnology on the food and food processing industries are growing in order to improve the food safety and nutritional effect.

 Prof. Soo -Jin CHOI obtained her bachelor’s degree in 1996 from Seoul Women’s University. She got her Ph.D. in pharmaco-toxicology in 2005 from Mus?um National d’Histoire Naturelle in Paris, France. Currently, She is the Seoul Women’s University professor of Food Science & Technology Department. Her research interests are Nanotoxicity, Nanofoods, Drug or Nutrient Delivery Systems, Mechanistic study, Natural toxins and Food Safety Risk Assessment.

 1. Nanotoxicity

 1) Nanotoxicity

 An emerging discipline, nanotoxicology provides information about the potential toxicological effects of nanomaterials on human health, their interaction with biological systems, and their risk assessment. Nanotoxicology is defined as “science of engineered nanodevices and nanostructures that deals with their effects in living organisms ”. Nanotoxicology elucidates the dose-response relationships between physicochemical properties of nanomaterials and toxic effects on biological system.

Moreover, recent growing interest in the uptake mechanism and trafficking of nanoparticles at cellular and systemic levels raises concern about their toxicity and biocompatibility. Some nanoparticles are massively taken up by cells through endocytosis, and they possess the capacity to penetrate barriers such as vascular endothelium and endothelial cells. This leads to easy uptake of nanoparticles by the human body compared to large particles, subsequently gaining access to cells, tissues, and organs. Nanotoxicology provides information about the physicochemical properties of nanomaterials and adverse effects on biological systems, since the toxicity of nanoparticles is not easily predictable from the known properties of larger bulk materials. Furthermore, nanomaterials used in medicine, pharmaceutics, cosmetics, and food are intensively designed to enhance cellular interaction and delivery of active molecules to target organs by controlling particle size and modifying surface charge and physicochemical properties.

 However, there are currently no general guidelines to assess the potential risk of nanoparticles and no regulatory framework for their human-related applications. Therefore, more vigorous investigations on the potential toxicity and safety assessment of nanoparticles are urgently needed to establish minimum safety standard. Such toxicological studies provide critical information on the medical applications of nanoparticles and contribute to the sustainable development of nanotechnology with safe and biocompatible levels.

 2) Toxicity in vitro

 The first step towards understanding how a nanomaterial will react in the body often involves in vitro cell culture studies. Compared to animal studies, cellular testing is les ethically ambiguous, is easier to control and reproduce, and is less expensive. In the case of cytotoxicity , controlling the experimental conditions is crucial to ensure that the measured cell death corresponds to the toxicity of the exposed nanoparticles versus the unstable culturing conditions. In addition, as nanoparticles can adsorb dyes and be redox active, it is important that the cytotoxicity assay is appropriate.

 3) Toxicity in vivo

 The majority of nanotoxicity research uses in vitro cell culture systems, requiring further verification in vivo complicated systems. In vitro cell culture models do not account for intercellular communication and exclude lymph, blood and bile transport mechanisms. Moreover, the correlation between in vitro and in vivo effects is not always consistent, requiring in vivo experiments to assume the toxicity obtained by cell culture systems. We perform toxicokinetic study (absorption, distribution, metabolism, excretion) and acute or sub-acute toxicity study in animal models.

 2. Nanofoods

 The impacts of nanotechnology on the food and food processing industries are growing in order to improve the food safety and nutritional effect. According to recent report of the Nanoforum , a group from Europe, on “Nanotechnology in Agriculture and Food”, “ nanofood ” is defined as nanotechnology techniques or tools which are used during cultivation, production, processing or packaging of the food. It does not mean atomically modified food or food produced by nanomachines.
Nanotechnology is envisioned to be used in food production, processing, preservation, flavor and color improvement, hygiene, safety, packaging and nutrient delivery system. Nanomaterials include nanocomposites , nanoclays , nanotubes and others. For example, various nanotechniques such as nanohybridization , emulsification, encapsulation, etc. have been extensively applied for storing and protecting fragile functional ingredients such as vitamins, aroma, nutrients, and colorants.

 3. Drug or Nutrient Delivery Systems

 Nutrient intake with high bioavailability represents a formidable challenge, because only a small proportion of molecules remain available following oral intake. There are several factors that influencing low bioavailability: insufficient gastric resident time, low permeability, low solubility within the gut, instability during food processing (temperature, oxygen, light) or in the gastro-intestinal (GI) tract (pH, enzymes, presence of other nutrients).

The concept of “Nutrient delivery system (NDS)” using nanomaterials is to develop protective mechanisms that maintain the active molecular form until the time of consumption and deliver this form to the physiological target organs. Various nanotechniques such as nanohybridization , emulsification and encapsulation can be applied for storing and protecting fragile functional ingredients such as vitamins, aroma, nutrients, colorants and etc. Encapsulated instable nutrients can be protected during food processing and preservation, released in a controlled manner, giving rise to increase gastric residence time, and absorbed effectively due to high absorption capacity of nanomaterials themselves to the gut, all of which increase high bioavailability in biological systems.

 4. Mechanistic study

 The essential requirement of nanoparticles for biological applications is that nanoparticles should efficiently traverse the cell membrane, which is most likely via endocytosis, pinocytosis or fusion-like mechanism. We elucidate the uptake mechanism, intracellular fate, and endocytosis-exocytosis pathway to provide critical information for the rational development of nano -bio materials.

 Some nanoparticles cause cell death, oxidative stress, inflammation response, and etc. We investigate intracellular signaling mechanism responsible for toxicity, together with genomic and proteomic approaches to provide mechanistic understanding of toxicological process of nanomaterials.

 5. Natural toxins

 Animal venoms are valuable sources of novel pharmacological tools whose specific actions are useful for characterizing their receptors. Hundreds of toxins from snakes, scorpions, spiders and marine invertebrates with a range of pharmacological activities have all been characterized.
S pider venoms contain a wide spectrum of biologically active substances, which selectively target a variety of vital physiological functions in both insects and mammals. The spider toxins are “short” polypeptides with molecular mass of 3 to 8 kDa and a structure that is held together by several disulfide bonds.

 There are two main groups of these peptides, the neurotoxins that target neuron receptors, neuron ions channels or presynaptic proteins involved in neurotransmitter release, and the non- neurotoxic peptides, such as necrotic peptides and antimicrobial peptides. As part of a general screening for antimalarial drugs, the potential of toxins from Psalmopoeus cambridgei , the Trinidad chevron tarantula was investigated. As a result, two novel peptides (PcFK1 and PcFK2, P salmopoeus c ambridgei F alciparum killer) that possess great antiplasmodial activity against the intra-erythrocyte stage of P. falciparum in vitro , but do not lyse erythrocytes or nucleated mammalian cells and do not inhibit neuromuscular function, despite their structural similarity to known neurotoxins.

 The structural properties of PcFK1 was also investigated to help understand the unique mechanism of action of this peptide and to enhance its utility as a lead compound for rational development of new antimalarial drugs. The three-dimensional solution structure was determined by 1 H two-dimensional NMR means of recombinant PcFK1, which is shown to belong to the ICK structural superfamily with structural determinants common to several neurotoxins acting as ion channels effectors. Unusual structural features using MS and MS/MS analysis of two different forms of recombinant PcFK1 (r-PcFK1) was identified and the connectivity of cysteine residues involved in disulfide bridges was also unambiguously determined. The mechanism of action of two antimalarial peptides is now under investigation.

 These works have been done by collaboration with Jacques Monod Institute (Paris, France), University of Aix-Marseille I and II (Marseille, France), and Museum National d’Histoire Naturelle (Paris, France).

 6. Food Safety Risk Assessment

 Risk assessment is a step in a risk management process. Risk assessment is the determination of quantitative or qualitative value of risk related to a concrete situation and a recognized hazard. Hazard Identification, aims to determine the qualitative nature of the potential adverse consequences of the contaminant (chemical, toxicant, food additive, etc.) and the strength of the evidence it can have that effect. This is done, for chemical hazards, by drawing from the results of the sciences of toxicology and epidemiology.

 Dose-Response Analysis, is determining the relationship between dose and the probability or the incidence of effect (dose-response assessment). The complexity of this step in many contexts derives mainly from the need to extrapolate results from experimental animals (e.g. mouse, rat) to humans, and/or from high to lower doses.