Graphene-Based Nanomaterials as Drug Delivery Carriers.

Graphene and graphene-based materials have been attracted in the past few years for biomedical applications due to their physicochemical and biological properties such as large surface area, chemical and mechanical stability, excellent conductivity, and good biocompatibility. Graphene-based materials not only surface modified graphene-based materials like graphene oxide (GO) or reduced graphene oxide (rGO) but also other structural forms like fullerene, carbon nanotubes, and graphite have been applied to advanced drug delivery systems. In this chapter, we review on the application of graphene-based materials in the drug delivery system with their physicochemical properties, methods for the preparation of graphene-based carriers, followed by analysis about their biodistribution and biosafety whether they are suitable as drug delivery carriers.

Graphene-Based Nanomaterials for Biomedical Imaging.

Graphene is sp2-hybridized carbon structure-based two-dimensional (2D) sheet. Graphene-based nanomaterials possess several features such as unique mechanical, electronic, thermal, and optical properties, high specific surface area, versatile surface functionalization, and biocompatibility, which attracted researcher's interests in various fields including biomedicine. In this chapter, we particularly focused on the biomedical imaging applications of graphene-based nanomaterials like graphene oxide (GO), reduced graphene oxide (rGO), graphene quantum dots (GQDs), graphene oxide quantum dots (GOQDs), and other derivatives, which utilize their outstanding optical properties. There are some biomedical imaging modalities using Graphene-based Nanomaterials, among which we will highlight fluorescence imaging, Raman imaging, magnetic resonance imaging, and photoacoustic imaging. We also discussed the brief perspectives and future application related to them.

Role of Graphene Family Nanomaterials in Skin Wound Healing and Regeneration.

Owing to astonishing properties such as the large surface area to volume ratio, mechanical stability, antimicrobial property, and collagen crosslinking, graphene family nanomaterials (GFNs) have been widely used in various biomedical applications including tissue regeneration. Many review literatures are available to compile the role of GFNs in cardiac, bone, and neuronal tissue regeneration. However, the contribution of GFNs in skin wound healing and tissue regeneration was not yet discussed. In the present review, we have highlighted the properties of GFNs and their application in skin wound healing. In addition, we have included challenges and future directions of GFNs in skin tissue regeneration in the portion of conclusion and perspectives.

Rotating Cylinder-Assisted Nanoimprint Lithography for Enhanced Chemisorbable Filtration Complemented by Molecularly Imprinted Polymers.

Rotating cylindrical stamp-based nanoimprint technique has many advantages, including the continuous fabrication of intriguing micro/nanostructures and rapid pattern transfer on a large scale. Despite these advantages, the previous nanoimprint lithography has rarely been used for producing sophisticated nanoscale patterns on a non-planar substrate that has many extended applications. Here, the simple integration of nanoimprinting process with a help of a transparent stamp wrapped on the cylindrical roll and UV optical source in the core to enable high-throughput pattern transfer, particularly on a fabric substrate is demonstrated. Moreover, as a functional resin material, this innovative strategy involves a synergistic approach on the synthesis of molecularly imprinted polymer, which are spatially organized free-standing perforated nanostructures such as nano/microscale lines, posts, and holes patterns on various woven or nonwoven blank substrates. The proposed materials can serve as a self-encoded filtration medium for selective separation of formaldehyde molecules. It is envisioned that the combinatorial fabrication process and attractive material paves the way for designing next-generation separation systems in use to capture industrial or household toxic substances.

Multifunctional Nanodroplets Encapsulating Naphthalocyanine and Perfluorohexane for Bimodal Image-Guided Therapy.

Although nanocarriers containing perfluorocarbon (PFC) have been widely investigated as an ultrasound (US) imaging agent and a high intensity focused ultrasound (HIFU) agent, these carriers have suffered from low stability and biocompatibility limiting their further biomedical applications. Here, we developed surface cross-linked polymer nanodroplets as a HIFU therapeutic agent guided by bimodal photoacoustic (PA) and US imaging. Pluronic F127 was reacted with 4-nitrophenyl chloroformate (NPC) and mixed with naphthalocyanine (Nc) in dichloromethane, which was added into the aqueous solution of amine-functionalized six-arm-branched poly(ethylene glycol) (PEG) to form an oil-in-water emulsion for the cross-linking reaction between the terminal NPC of Pluronic F127 and the primary amine of six-arm PEG. The resulting solution was sonicated with liquid perfluorohexane (PFH) to prepare PEG cross-linked Pluronic F127 nanoparticles encapsulating Nc and PFH (Nc/PFH@PCPN). Nc/PFH@PCPN appeared to be stable without any coalescence or vaporization in the physiological condition. Upon the application of HIFU, Nc/PFH@PCPN was vaporized and showed increased US intensity for 180 min. The Nc dye in the nanodroplets enabled the stable encapsulation of PFH and the bimodal US/PA imaging. In vivo PA/US image-guided HIFU ablation therapy confirmed that the nanodroplets increased the cavitation effect, induced necrosis and apoptosis of tumor cells, and reduced tumor growth significantly for 12 days. Taken together, the multifunctional Nc/PFH@PCPN was successfully developed as a new platform for PA/US image-guided HIFU therapy.

Different associations of albuminuria with total and cardiovascular mortality by concentrations of persistent organic pollutants in the elderly.

Epidemiologic studies have indicated that albuminuria is associated with mortality from all causes and cardiovascular disease (CVD), with substantial heterogeneity. We evaluated if the associations of urine albumin creatinine ratio (ACR) with all-cause and CVD mortality differed depending on serum concentrations of persistent organic pollutants (POPs), strong lipophilic chemical mixtures with very long half-lives, which are recently linked to many degenerative diseases. Study subjects were participants of the National Health and Nutrition Examination Survey 1999-2004 who were 60 years or older at baseline (n=1215 and 1067 for organochlorine pesticides (OCPs) and other POPs, respectively). They were followed-up through 2011 (mean follow-up periods: 8.1 and 8.0 years for OCPs and other POPs, respectively). The associations between the ACR and all-cause mortality significantly differed by the serum levels of POPs, especially organochlorine pesticides (OCPs; Pinteraction<0.01). Stratified analyses indicated that the associations between ACR and all-cause mortality became stronger as the serum levels of OCPs increased. Among the elderly with the highest tertile of OCPs, the adjusted hazard ratios were 1.0, 1.1, and 2.9 (Ptrend<0.01) across the categories of ACR (<10, 10-<30, and ≥30mg/g); however, ACR was not clearly related to mortality among the elderly with the lowest tertile of OCPs. CVD mortality showed similar interactions, as noted for all-cause mortality (Pinteraction<0.01). The different associations between albuminuria and mortality by the serum OCP levels and the little association among the elderly with low serum OCPs levels suggest that OCPs play an important role in albuminuria-related death risk. However, these findings need to be replicated in other cohort studies.

Noninvasive Transdermal Vaccination Using Hyaluronan Nanocarriers and Laser Adjuvant.

Vaccines are commonly administered by injection using needles. Although transdermal microneedles are less-invasive promising alternatives, needle-free topical vaccination without involving physical damage to the natural skin barrier is still sought after as it can further reduce needle-induced anxiety and simply administration. However, this long-standing goal has been elusive since the intact skin is impermeable to most macromolecules. Here, we show an efficient, non-invasive transdermal vaccination in mice by employing two key innovations: first, the use of hyaluronan (HA) as vaccine carriers and, second, non-ablative laser adjuvants. Conjugates of a model vaccine ovalbumin (OVA) and HA-HA-OVA conjugates-induced more effective maturation of dendritic cells in vitro, compared to OVA or HA alone, through synergistic HA receptor-mediated effects. Following topical administration in the back skin, HA-OVA conjugates penetrated into the epidermis and dermis in murine and porcine skins up to 30% of the total applied quantity, as revealed by intravital microscopy and quantitative fluorescence assay. Topical administration of HA-OVA conjugates significantly elevated both anti-OVA IgG antibody levels in serum and IgA antibody levels in bronchioalveolar lavage, with peak levels at 4 weeks, while OVA alone had a negligible effect. An OVA challenge at week 8 elicited strong immune-recall humoral responses. With pre-treatment of the skin using non-ablative fractional laser beams (1410 nm wavelength, 10 ms pulse duration, 0.2 mJ/pulse) as laser adjuvant, strong immunization was achieved with much reduced doses of HA-OVA (1 mg/kg OVA). Our results demonstrate the potential of the non-invasive patch-type transdermal vaccination platform.

Bioimaging of Hyaluronate-Interferon α Conjugates Using a Non-Interfering Zwitterionic Fluorophore.

We conducted real-time bioimaging of the hyaluronate-interferon α (HA-IFNα) conjugate using a biologically inert zwitterionic fluorophore of ZW800-1 for the treatment of hepatitis C virus (HCV) infection. ZW800-1 was labeled on the IFNα molecule of the HA-IFNα conjugate to investigate its biodistribution and clearance without altering its physicochemical and targeting characteristics. Confocal microscopy clearly visualized the effective in vitro cellular uptake of the HA-IFNα conjugate to HepG2 cells. After verifying the biological activity in Daudi cells, we conducted the pharmacokinetic analysis of the HA-IFNα conjugate, which confirmed its target-specific delivery to the liver with a prolonged residence time longer than that of PEGylated IFNα. In vivo and ex vivo bioimaging of the ZW800-1-labeled HA-IFNα conjugate directly showed real-time biodistribution and clearance of the conjugate that are consistent with the biological behaviors analyzed by an enzyme-linked immunosorbent assay. Furthermore, the elevated level of OAS1 mRNA in the liver confirmed in vivo antiviral activity of HA-IFNα conjugates. With the data taken together, we could confirm the feasibility of ZW800-1 as a biologically inert fluorophore and target-specific HA-IFNα conjugate for the treatment of HCV infection.

Persistent organic pollutants and promoter hypermethylation of the O(6)-methylguanine-DNA methyltransferase gene.

Promoter hypermethylation of the O(6)-methylguanine-DNA methyltransferase (MGMT) DNA repair gene is important during carcinogenesis. We explored whether organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), were associated with hypermethylation of the MGMT gene promoter in peripheral leukocytes among 368 Koreans without cancer. Hypermethylation decreased as OCPs increased (Ptrend = 0.02), while PCB concentrations showed an inverted U-shaped association (Pquadratic < 0.01). The prevalence of MGMT promoter hypermethylation was highest within the 2nd quintile of the PCB summary score (28.4%), while it was only 2.7% in the upper 10% score. Chronic exposure to these chemicals may affect methylation of the MGMT promoter, with possibly non-monotonic dose response relationships.

Associations of organochlorine pesticides and polychlorinated biphenyls with total, cardiovascular, and cancer mortality in elders with differing fat mass.

BACKGROUND: We investigated if certain persistent organic pollutants (POPs), namely polychlorinated biphenyls (PCBs) and organochlorine (OC) pesticides, predicted total, cardiovascular disease (CVD), and cancer mortality among the elderly, with the hypothesis that associations differ by the amount of fat mass. METHODS: We studied serum concentrations of 11 PCBs in 633 elders (age≥70 years) and of 5 OC pesticides in 675 elders within the National Health and Nutrition Examination Survey (NHANES) 1999-2004. Mean follow-up was 4.1-years. RESULTS: Neither PCBs nor OC pesticides were associated with total mortality when fat mass was not considered in analyses. However, associations of PCBs and OC pesticides with total mortality depended on fat mass (Pinteraction<0.01 and 0.06, respectively). PCBs associated inversely with total mortality for high fat mass, but not for lower fat mass. On the contrary, OC pesticides associated positively with total mortality for low fat mass and this association weakened at higher fat mass. The interaction was also observed with CVD mortality. In elders with low fat mass, higher PCBs associated with 2-3 fold higher risk of CVD mortality, while this association was absent in elders with more fat mass (Pinteraction=0.03). The positive association between OC pesticides and CVD mortality was also observed only among elderly with low fat mass (Pinteraction=0.03). CONCLUSIONS: The possibility of interaction between POPs and the amount of fat mass on risk of mortality from chronic diseases is clinically important in modern societies with an obesity epidemic and requires confirmation in other studies with larger sample size.