Gold nanoparticles and diclofenac diethylammonium administered by iontophoresis reduce inflammatory cytokines expression in Achilles tendinitis

α-Lipoic acid loaded hollow gold nanoparticles designed for osteoporosis treatment: preparation, characterization and in vitro evaluation

Osteoporosis is a common disease among the ageing society. Oxidative stress caused by excessive accumulation of reactive oxygen species (ROS) is the aetiology of osteoporosis. α-Lipoic acid (ALA) is an antioxidant in the body, which can eliminate excess ROS in the body and inhibits levels of oxidative stress in cells. Herein, we designed PEGylated hollow gold nanoparticles (HGNPs) loaded with ALA (mPEG@HGNPs-ALA) to remove ROS in the treatment of osteoporosis. First, mPEG@HGNPs with a particle size of ∼63 nm has been successfully synthesized. By comparing the drug loading of mPEG@HGNPs, it was concluded that the optimal mass ratio of mPEG@HGNPs (calculated by the amount of gold) to ALA was ∼1:2. ABTS antioxidant assay showed that free radical removal ability. In vitro results revealed that the preparation had good biocompatibility. At the gold concentration of 1-150 μg/mL, the cell viability of mPEG@HGNPs was more than 100%, which indicated that it could promote the proliferation of osteoblasts. What's more, mPEG@HGNPs-ALA could effectively remove the ROS caused by H₂O₂ injury and improve the cell viability. According to these results, it can be considered that mPEG@HGNPs-ALA has the potential to treat osteoporosis.

An overview of the material science and knowledge of nanomedicine, bioscaffolds, and tissue engineering for tendon restoration

Tendon wounds are a worldwide health issue affecting millions of people annually. Due to the characteristics of tendons, their natural restoration is a complicated and lengthy process. With the advancement of bioengineering, biomaterials, and cell biology, a new science, tissue engineering, has developed. In this field, numerous ways have been offered. As increasingly intricate and natural structures resembling tendons are produced, the results are encouraging. This study highlights the nature of the tendon and the standard cures that have thus far been utilized. Then, a comparison is made between the many tendon tissue engineering methodologies proposed to date, concentrating on the ingredients required to gain the structures that enable appropriate tendon renewal: cells, growth factors, scaffolds, and scaffold formation methods. The analysis of all these factors enables a global understanding of the impact of each component employed in tendon restoration, thereby shedding light on potential future approaches involving the creation of novel combinations of materials, cells, designs, and bioactive molecules for the restoration of a functional tendon.

A mini-review on the emerging role of nanotechnology in revolutionizing orthopedic surgery: challenges and the road ahead

An emerging application of nanotechnology in medicine currently being developed involves employing nanoparticles to deliver drugs, heat, light, or other substances to specific types of cells (such as cancer cells). As most biological molecules exist and function at the nanoscale, engineering and manipulating matter at the molecular level has many advantages in the field of medicine (nanomedicine). Although encouraging, it remains unclear how much of this will ultimately result in improved patient care. In surgical specialties, clinically relevant nanotechnology applications include the creation of surgical instruments, suture materials, imaging, targeted drug therapy, visualization methods, and wound healing techniques. Burn lesion and scar management is an essential nanotechnology application. Prevention, diagnosis, and treatment of numerous orthopedic conditions are crucial technological aspects for patients' functional recovery. Orthopedic surgery is a specialty that deals with the diagnosis and treatment of musculoskeletal disorders. In recent years, the field of orthopedics has been revolutionized by the advent of nanotechnology. Using biomaterials comprised of nanoparticles and structures, it is possible to substantially enhance the efficacy of such interactions through nanoscale material modifications. This serves as the foundation for the majority of orthopedic nanotechnology applications. In orthopedic surgery, nanotechnology has been applied to improve surgical outcomes, enhance bone healing, and reduce complications associated with orthopedic procedures. This mini-review summarizes the present state of nanotechnology in orthopedic surgery, including its applications as well as possible future directions.

Microcurrent and Gold Nanoparticles Combined with Hyaluronic Acid Accelerates Wound Healing

This study aimed to investigate the effects of iontophoresis and hyaluronic acid (HA) combined with a gold nanoparticle (GNP) solution in an excisional wound model. Fifty Wistar rats (n = 10/group) were randomly assigned to the following groups: excisional wound (EW); EW + MC; EW + MC + HA; EW + MC + GNPs; and EW + MC + HA + GNPs. The animals were induced to a circular excision, and treatment started 24 h after injury with microcurrents (300 µA) containing gel with HA (0.9%) and/or GNPs (30 mg/L) in the electrodes (1 mL) for 7 days. The animals were euthanized 12 h after the last treatment application. The results demonstrate a reduction in the levels of pro-inflammatory cytokines (IFNϒ, IL-1β, TNFα, and IL-6) in the group in which the therapies were combined, and they show increased levels of anti-inflammatory cytokines (IL-4 and IL-10) and growth factors (FGF and TGF-β) in the EW + MC + HA and EW + MC + HA + GNPs groups. As for the levels of dichlorofluorescein (DCF) and nitrite, as well as oxidative damage (carbonyl and sulfhydryl), they decreased in the combined therapy group when compared to the control group. Regarding antioxidant defense, there was an increase in glutathione (GSH) and a decrease in superoxide dismutase (SOD) in the combined therapy group. A histological analysis showed reduced inflammatory infiltrate in the MC-treated groups and in the combination therapy group. There was an increase in the wound contraction rate in all treated groups when compared to the control group, proving that the proposed therapies are effective in the epithelial healing process. The results of this study demonstrate that the therapies in combination favor the tissue repair process more significantly than the therapies in isolation.

Tendon Tissue Repair in Prospective of Drug Delivery, Regenerative Medicines, and Innovative Bioscaffolds

The natural healing capacity of the tendon tissue is limited due to the hypovascular and cellular nature of this tissue. So far, several conventional approaches have been tested for tendon repair to accelerate the healing process, but all these approaches have their own advantages and limitations. Regenerative medicine and tissue engineering are interdisciplinary fields that aspire to develop novel medical devices, innovative bioscaffold, and nanomedicine, by combining different cell sources, biodegradable materials, immune modulators, and nanoparticles for tendon tissue repair. Different studies supported the idea that bioscaffolds can provide an alternative for tendon augmentation with an enormous therapeutic potentiality. However, available data are lacking to allow definitive conclusion on the use of bioscaffolds for tendon regeneration and repairing. In this review, we provide an overview of the current basic understanding and material science in the field of bioscaffolds, nanomedicine, and tissue engineering for tendon repair.

Gold Nanoparticles: Multifaceted Roles in the Management of Autoimmune Disorders

Gold nanoparticles (GNPs) have been recently applied for various diagnostic and therapeutic purposes. The unique properties of these nanoparticles (NPs), such as relative ease of synthesis in various sizes, shapes and charges, stability, high drug-loading capacity and relative availability for modification accompanied by non-cytotoxicity and biocompatibility, make them an ideal field of research in bio-nanotechnology. Moreover, their potential to alleviate various inflammatory factors, nitrite species, and reactive oxygen production and the capacity to deliver therapeutic agents has attracted attention for further studies in inflammatory and autoimmune disorders. Furthermore, the characteristics of GNPs and surface modification can modulate their toxicity, biodistribution, biocompatibility, and effects. This review discusses in vitro and in vivo effects of GNPs and their functionalized forms in managing various autoimmune disorders (Ads) such as rheumatoid arthritis, type 1 diabetes, and multiple sclerosis.

Transdermal Delivery of Gold Nanoparticles by a Soybean Oil-Based Oleogel under Iontophoresis

Developing a facile mechanism for transporting nanoparticles across the whole skin by overcoming the stratum corneum is a challenging task. Herein, a stimuli-responsive and noninvasive transport of gold nanoparticles (AuNPs) has been reported through the fabrication of AuNP-incorporated soybean oil-based oleogels (AuG) using stearic acid as a gelator. A series of AuG was formulated by incorporating different proportions of AuNPs and a fixed amount of ciprofloxacin hydrochloride (drug) to establish that the composition with the highest concentration of AuNP (d-AuG4) was associated with the best iontophoretic response, validated via the corresponding in vitro drug release under AC field-induced iontophoresis. The sample d-AuG4 exhibited both drug and AuNP permeation across the whole pig ear skin thickness within as early as 1 h under the iontophoresis condition. With relevant control experiments, it was shown that the transport of AuNPs through the stratum corneum tissue and across the whole skin was possible upon the simultaneous fulfillment of two conditions: the presence of a skin permeation enhancer (stearic acid) within the oleogel and iontophoresis. While the literature reported that the permeation time for any free inorganic nanoparticle through the full-skin thickness varied within a few days, the permeation enhancement technique developed here reduced the corresponding delivery time for the AuNPs to a few hours. The extent of AuNP permeation that occurred in the microgram (per cm^-2) scale was found to be affected by the duration of iontophoresis, suggesting that AuNPs' rapid transdermal entry can be simultaneously triggered and modulated by iontophoretic conditions.

Effects of the Association between Photobiomodulation and Hyaluronic Acid Linked Gold Nanoparticles in Wound Healing

Healing is the process responsible for restoring the integrity of the body's internal or external structures when they rupture. Photobiomodulation (PBM) stands out as one of the most efficient resources in the treatment of epithelial lesions, as well as hyaluronic acid (HA), which has been emerging as a new molecule for the treatment of dermal and epidermal lesions. The biological application of gold nanoparticles (GNPs) shows promising results. This study aimed to investigate the possible anti-inflammatory and antioxidant effects of the association between PBM and GNPs-linked HA in an epithelial lesion model. Fifty Wistar rats were randomly distributed in the Control Group (CG); (PBM); (PBM + HA); (PBM + GNPs); (PBM + GNPs-HA). The animals were anesthetized, trichotomized, and induced to a surgical incision in the dorsal region. Topical treatment with HA (0.9%) and/or GNPs (30 mg/kg) occurred daily associated with 904 nm laser irradiation, dose of 5 J/cm², which started 24 h after the lesion and was performed daily until the seventh day. The levels of proinflammatory (IL1 and TNFα), anti-inflammatory (IL10 and IL4) and growth factors (FGF and TGFβ) cytokines and oxidative stress parameters were evaluated, besides histological analysis through inflammatory infiltrate, fibroblasts, new vessels, and collagen production area. Finally, for the analysis of wound size reduction, digital images were performed and subsequently analyzed by the IMAGEJ software. The treated groups showed a decrease in proinflammatory cytokine levels and an increase in anti-inflammatory cytokines. TGFβ and FGF levels also increased in the treated groups, especially in the combination therapy group (PBM + GNPs-HA). Regarding the oxidative stress parameters, MPO, DCF, and Nitrite levels decreased in the treated groups, as well as the oxidative damage (Carbonyl and Thiol groups). In contrast, antioxidant defense increased in the groups with the appropriate therapies proposed compared to the control group. Histological sections were analyzed where the inflammatory infiltrate was lower in the PBM + GNPs-HA group. The number of fibroblasts was higher in the PBM and PBM + HA treated groups, whereas collagen production was higher in all treated groups. Finally, in the analysis of the wound area contraction, the injury group presented a larger area in cm² compared to the other groups. Taken together, these results allow us to observe that the combination of PBM + GNPs-HA optimized the secretion of anti-inflammatory cytokines, proliferation and cell differentiation growth factors, and made an earlier transition to the chronic phase, contributing to the repair process.

Physical triggering strategies for drug delivery

Physically triggered systems hold promise for improving drug delivery by enhancing the controllability of drug accumulation and release, lowering non-specific toxicity, and facilitating clinical translation. Several external physical stimuli including ultrasound, light, electric fields and magnetic fields have been used to control drug delivery and they share some common features such as spatial targeting, spatiotemporal control, and minimal invasiveness. At the same time, they possess several distinctive features in terms of interactions with biological entities and/or the extent of stimulus response. Here, we review the key advances of such systems with a focus on discussing their physical mechanisms, the design rationales, and translational challenges.

Effects of treatment with gold nanoparticles in a model of acute pulmonary inflammation induced by lipopolysaccharide

The bacterial lipopolysaccharide (LPS) is a highly toxic molecule derived from the outer membrane of gram-negative bacteria. LPS endotoxin affects the lungs and is used as a model of acute pulmonary inflammation affecting the cellular morphology of the organ. Previously, gold nanoparticles (GNPs) have been shown to demonstrate anti-inflammatory and antioxidative activity in muscle and epithelial injury models. The objective of this study was to investigate the effect of the intraperitoneal treatment using GNPs on the inflammatory response and pulmonary oxidative stress induced by LPS. Wistar rats were divided into four groups (N = 10): Sham; Sham + GNPs 2.5 mg/kg; LPS; and LPS + GNPs 2.5 mg/kg. Treatment with LPS upregulated the levels of markers of cellular and hepatic damage (CK, LDH, AST, and alanine aminotransferase); however, the group treated with only GNPs exhibited no toxicity. Treatment with GNPs reversed LPS-induced changes with respect to total peritoneal leukocyte count and the pulmonary levels of pro-inflammatory cytokines (IFN-γ and IL-6). Histological analysis revealed that treatment with GNPs reversed the increase in alveolar septum thickness due to LPS-induced fibrosis. In addition, treatment with GNPs decreased production of oxidants (nitrite and DCFH), reduced oxidative damage (carbonyl and sulfhydryl), and downregulated activities of superoxide dismutase and catalase. Treatment with GNPs did not showed toxicity; however, it exhibited anti-inflammatory and antioxidative activity that reversed morphological alterations induced by LPS.

Therapeutic effects of iontophoresis with gold nanoparticles in the repair of traumatic muscle injury

Studies have shown the benefits of gold nanoparticles (GNPs) in muscle and epithelial injury models. In physiotherapy, the use of the microcurrent apparatus is associated with certain drugs (Iontophoresis) to increase the topical penetration and to associate the effects of both therapies. Therefore, the objective of this study was to investigate the effects of iontophoresis along with GNPs in the skeletal muscle of rats exposed to a traumatic muscle injury. We utilised 50 Wistar rats randomly divided in to five experimental groups (n = 10): Control group (CG); Muscle injury group (MI); MI + GNPs (20 nm, 30 mg kg^-1); MI + Microcurrent (300 μA); and MI + Microcurrent + GNPs. The treatment was performed daily for 7 days, with the first session starting at 24 h after the muscle injury. The animals were sacrificed and the gastrocnemius muscle was surgically removedand stored for the proper evaluations. The group that received iontophoresis with GNPs showed significant differences in inflammation and oxidative stress parameters and in the histopathological evaluation showed preserved morphology. In addition, we observed an improvement in the locomotor response and pain symptoms of these animals. These results suggest that the association of boththerapies accelerates the inflammatory response of the injured limb.

Effects of chronic treatment with gold nanoparticles on inflammatory responses and oxidative stress in Mdx mice

Duchenne muscular dystrophy (DMD) is an X-linked recessive hereditary myopathy characterised by progressive muscle degeneration in male children. As a consequence of DMD, increased inflammation and oxidative stress occur in muscle tissue along with morphological changes. Several studies have reported anti-inflammatory and antioxidant effects of gold nanoparticles (GNP) in muscle injury models. The objective of this study was to evaluate these effects along with the impacts of the disease on histopathological changes following chronic administration of GNP to Mdx mice. Two-month-old Mdx mice were separated into five groups of eight individuals each, as follows: wild-type (WT), Mdx-modified without treatment, Mdx + 2.5 mg/kg GNP, Mdx + 7.0 mg/kg GNP and Mdx + 21 mg/kg GNP. GNP with a mean diameter of 20 nm were injected subcutaneously at concentrations of 2.5, 7.0 and 21 mg/kg. Treatments continued for 30 d with injections administered at 48-h intervals. Twenty-four hours after the last injection, the animals were killed and the central region of the gastrocnemius muscle was surgically removed. Chronic administration of GNP reduced inflammation in the gastrocnemius muscle of Mdx mice and reduced morphological alterations due to inflammatory responses to muscular dystrophy. In addition, GNP also demonstrated antioxidant potential by reducing the production of reactive oxygen and nitrogen species, reducing oxidative damage and improving antioxidant activity.

Cytokines in tendon disease: A Systematic Review

OBJECTIVES

Emerging evidence indicates that tendon disease is an active process with inflammation that is critical to disease onset and progression. However, the key cytokines responsible for driving and sustaining inflammation have not been identified.

METHODS

We performed a systematic review of the literature using MEDLINE (U.S. National Library of Medicine, Bethesda, Maryland) in March 2017. Studies reporting the expression of interleukins (ILs), tumour necrosis factor alpha (TNF-α) and interferon gamma in diseased human tendon tissues, and animal models of tendon injury or exercise in comparison with healthy control tissues were included.

RESULTS

IL-1β, IL-6, IL-10, and TNF-α are the cytokines that have been most frequently investigated. In clinical samples of tendinopathy and tendon tears, the expression of TNF-α tended not to change but IL-6 increased in tears. Healthy human tendons showed increased IL-6 expression after exercise; however, IL-10 remained unchanged. Animal tendon injury models showed that IL-1β, IL-6, and TNF-α tend to increase from the early phase of tendon healing. In animal exercise studies, IL-1β expression showed a tendency to increase at the early stage after exercise, but IL-10 expression remained unchanged with exercise.

CONCLUSIONS

This review highlights the roles of IL-1β, IL-6, IL-10, and TNF-α in the development of tendon disease, during tendon healing, and in response to exercise. However, there is evidence accumulating that suggests that other cytokines are also contributing to tendon inflammatory processes. Further work with hypothesis-free methods is warranted in order to identify the key cytokines, with subsequent mechanistic and interaction studies to elucidate their roles in tendon disease development.Cite this article: W. Morita, S. G. Dakin, S. J. B. Snelling, A. J. Carr. Cytokines in tendon disease: A Systematic Review. Bone Joint Res 2017;6:656-664. DOI: 10.1302/2046-3758.612.BJR-2017-0112.R1.

Nanomaterials for transdermal drug delivery: beyond the state of the art of liposomal structures

A wide range of biomedical materials have been proposed to meet the different needs for controlled oral or intravenous drug delivery. The advantages of oral delivery such as self-administration of a pre-determined drug dose at defined time intervals makes it the most convenient means for the delivery of small molecular drugs. It fails however to delivery therapeutic macromolecules due to rapid degradation in the stomach and size-limited transport across the epithelium. The primary mode of administration of macromolecules is presently via injection. This administration mode is not without limitations, as the invasive nature of injections elicits pain and decreases patients' compliance. Alternative routes for drug delivery have been looked for, one being the skin. Delivery of drugs via the skin is based on the therapeutics penetrating the stratum corneum (SC) with the advantage of overcoming first-pass metabolism of drugs, to deliver drugs with a short-half-life time more easily and to eliminate frequent administrations to maintain constant drug delivery. The transdermal market still remains limited to a narrow range of drugs. The low permeability of the SC to water-soluble and macromolecular drugs poses significant challenges to transdermal administration via passive diffusion through the skin, as is the case for all topically administered drug formulations intended to bring the therapeutic into the general circulation. To widen the scope of drugs for transdermal delivery, new procedures to enhance skin permeation to hydrophilic drugs and macromolecules are under development. Next to the integration of skin enhancers into pharmaceutical formulations, nanoparticles based on lipid carriers have been widely considered and reviewed. While being briefly reviewed here, the main focus of this article is on current advancements using polymeric and metallic nanoparticles. Next to these passive technologies, the handful of active technologies for local and systemic transdermal drug delivery will be discussed and put into perspective. While passive approaches dominate the literature and the transdermal market, active delivery based on microneedles or iontophoresis approaches have shown great promise for transdermal drug delivery and have entered the market, in the last decade. This review gives an overall idea of the current activities in this field.

Nanotechnology in orthopedics

Nanotechnology has revolutionized science and consumer products for several decades. Most recently, its applications to the fields of medicine and biology have improved drug delivery, medical diagnostics, and manufacturing. Recent research of this modern technology has demonstrated its potential with novel forms of disease detection and intervention, particularly within orthopedics. Nanomedicine has transformed orthopedics through recent advances in bone tissue engineering, implantable materials, diagnosis and therapeutics, and surface adhesives. The potential for nanotechnology within the field of orthopedics is vast and much of it appears to be untapped, though not without accompanying obstacles.

Nanoparticles for Tendon Healing and Regeneration: Literature Review

Tendon injuries are commonly met in the emergency department. Unfortunately, tendon tissue has limited regeneration potential and usually the consequent formation of scar tissue causes inferior mechanical properties. Nanoparticles could be used in different way to improve tendon healing and regeneration, ranging from scaffolds manufacturing (increasing the strength and endurance or anti-adhesions, anti-microbial, and anti-inflammatory properties) to gene therapy. This paper aims to summarize the most relevant studies showing the potential application of nanoparticles for tendon tissue regeneration.

Multi-Shell Hollow Nanogels with Responsive Shell Permeability

We report on hollow shell-shell nanogels with two polymer shells that have different volume phase transition temperatures. By means of small angle neutron scattering (SANS) employing contrast variation and molecular dynamics (MD) simulations we show that hollow shell-shell nanocontainers are ideal systems for controlled drug delivery: The temperature responsive swelling of the inner shell controls the uptake and release, while the thermoresponsive swelling of the outer shell controls the size of the void and the colloidal stability. At temperatures between 32 °C < T < 42 °C, the hollow nanocontainers provide a significant void, which is even larger than the initial core size of the template, and they possess a high colloidal stability due to the steric stabilization of the swollen outer shell. Computer simulations showed, that temperature induced switching of the permeability of the inner shell allows for the encapsulation in and release of molecules from the cavity.

Gold nanoparticles alter parameters of oxidative stress and energy metabolism in organs of adult rats

This study evaluated the parameters of oxidative stress and energy metabolism after the acute and long-term administration of gold nanoparticles (GNPs, 10 and 30 nm in diameter) in different organs of rats. Adult male Wistar rats received a single intraperitoneal injection or repeated injections (once daily for 28 days) of saline solution, GNPs-10 or GNPs-30. Twenty-four hours after the last administration, the animals were killed, and the liver, kidney, and heart were isolated for biochemical analysis. We demonstrated that acute administration of GNPs-30 increased the TBARS levels, and that GNPs-10 increased the carbonyl protein levels. The long-term administration of GNPs-10 increased the TBARS levels, and the carbonyl protein levels were increased by GNPs-30. Acute administration of GNPs-10 and GNPs-30 increased SOD activity. Long-term administration of GNPs-30 increased SOD activity. Acute administration of GNPs-10 decreased the activity of CAT, whereas long-term administration of GNP-10 and GNP-30 altered CAT activity randomly. Our results also demonstrated that acute GNPs-30 administration decreased energy metabolism, especially in the liver and heart. Long-term GNPs-10 administration increased energy metabolism in the liver and decreased energy metabolism in the kidney and heart, whereas long-term GNPs-30 administration increased energy metabolism in the heart. The results of our study are consistent with other studies conducted in our research group and reinforce the fact that GNPs can lead to oxidative damage, which is responsible for DNA damage and alterations in energy metabolism.

Effect of oral administration of commercial gold nanocolloid on peripheral blood leukocytes in mice

During the last few decades, owing to their unique properties, gold nanoparticles (AuNPs) have found numerous biomedical applications. Studies on rodents prove that AuNPs entering an organism easily reach the bloodstream and undergo wide tissue distribution. The presence of nanoparticles inside blood and bone marrow cells of exposed animals may implicate its influence on hematopoesis and the functions of peripheral blood leukocytes. The aim of this study was to determine the effect of oral administration of commercial gold nanocolloid, recommended by the producer as a dietary supplement, on the percentage of lymphocyte populations and proliferative response, as well as the activity of phagocytes in the peripheral blood of mice. The colloid was given to the animals in three different doses (0.25, 2.5, 25 ppm), for three different time periods (7, 14, 28 days). Mice given nanoparticles showed increased activity of phagocytes and some changes in the lymphocyte phenotypes. The elevated activity of granulocytes and monocytes, in terms of both phagocytic and respiratory burst activity, was transient and noticed only after a short time of administration, which may indicate some adaptability of blood phagocytes to prolonged presence of gold nanoparticles in the body. However, phenotypic modifications among lymphocytes in the group of animals given the middle dose of colloid (i.e. increased percentage of B and CD4+CD8+ DP T cells) did not occur until after the 28-day administration, which in turn seems indicative of some immune dysregulation due to the prolonged contact with nanogold.

Gold nanoparticles and/or N-acetylcysteine mediate carrageenan-induced inflammation and oxidative stress in a concentration-dependent manner

We report the effect of gold nanoparticles (AuNP) in an acute inflammation model induced by carrageenan (CG) and compared this effect with those induced by the antioxidant N-acetylcysteine (NAC) alone and by the synergistic effect of NAC and AuNP together. Male Wistar rats received saline or saline containing CG administered into the pleural cavity, and some rats also received NAC (20 mg/kg) subcutaneously and/or AuNP administered into the pleural cavity immediately after surgery. Four hours later, the rats were sacrificed and pleural exudates obtained for evaluation of cytokine levels and myeloperoxidase activities. Oxidative stress parameters were also evaluated in the lungs. The results demonstrated that the inflammatory process caused by the administration of CG into the pleural cavity resulted in a substantial increase in the levels of tumor necrosis factor-α, interleukin-1β, and myeloperoxidase and a reduction in interleukin-10 levels. These levels seem to be reversed after different treatments in animals. Antioxidant enzymes exhibited positive responses after treatment of NAC + AuNP, and all treatments were effective at reducing lipid peroxidation and oxidation of thiol groups induced by CG. These findings suggest that small compounds, such as NAC plus AuNP, may be useful in the treatment of conditions associated with local inflammation.

Nanotechnology: current concepts in orthopaedic surgery and future directions

Nanotechnology is the study, production and controlled manipulation of materials with a grain size < 100 nm. At this level, the laws of classical mechanics fall away and those of quantum mechanics take over, resulting in unique behaviour of matter in terms of melting point, conductivity and reactivity. Additionally, and likely more significant, as grain size decreases, the ratio of surface area to volume drastically increases, allowing for greater interaction between implants and the surrounding cellular environment. This favourable increase in surface area plays an important role in mesenchymal cell differentiation and ultimately bone-implant interactions. Basic science and translational research have revealed important potential applications for nanotechnology in orthopaedic surgery, particularly with regard to improving the interaction between implants and host bone. Nanophase materials more closely match the architecture of native trabecular bone, thereby greatly improving the osseo-integration of orthopaedic implants. Nanophase-coated prostheses can also reduce bacterial adhesion more than conventionally surfaced prostheses. Nanophase selenium has shown great promise when used for tumour reconstructions, as has nanophase silver in the management of traumatic wounds. Nanophase silver may significantly improve healing of peripheral nerve injuries, and nanophase gold has powerful anti-inflammatory effects on tendon inflammation. Considerable advances must be made in our understanding of the potential health risks of production, implantation and wear patterns of nanophase devices before they are approved for clinical use. Their potential, however, is considerable, and is likely to benefit us all in the future.

Acute and chronic administration of gold nanoparticles cause DNA damage in the cerebral cortex of adult rats

The use of gold nanoparticles is increasing in medicine; however, their toxic effects remain to be elucidated. Studies show that gold nanoparticles can cross the blood-brain barrier, as well as accumulate in the brain. Therefore, this study was undertaken to better understand the effects of gold nanoparticles on rat brains. DNA damage parameters were evaluated in the cerebral cortex of adult rats submitted to acute and chronic administration of gold nanoparticles of two different diameters: 10 and 30nm. During acute administration, adult rats received a single intraperitoneal injection of either gold nanoparticles or saline solution. During chronic administration, adult rats received a daily single injection for 28 days of the same gold nanoparticles or saline solution. Twenty-four hours after either single (acute) or last injection (chronic), the rats were euthanized by decapitation, their brains removed, and the cerebral cortices isolated for evaluation of DNA damage parameters. Our study showed that acute administration of gold nanoparticles in adult rats presented higher levels of damage frequency and damage index in their DNA compared to the control group. It was also observed that gold nanoparticles of 30nm presented higher levels of damage frequency and damage index in the DNA compared to the 10nm ones. When comparing the effects of chronic administration of gold nanoparticles of 10 and 30nm, we observed that occurred significant different index and frequency damage, comparing with control group. However, there is no difference between the 10 and 30nm groups in the levels of DNA damage for both parameters of the Comet assay. Results suggest that gold nanoparticles for both sizes cause DNA damage for chronic as well as acute treatments, although a higher damage was observed for the chronic one.

Stimuli-responsive nanocarriers for drug delivery

Spurred by recent progress in materials chemistry and drug delivery, stimuli-responsive devices that deliver a drug in spatial-, temporal- and dosage-controlled fashions have become possible. Implementation of such devices requires the use of biocompatible materials that are susceptible to a specific physical incitement or that, in response to a specific stimulus, undergo a protonation, a hydrolytic cleavage or a (supra)molecular conformational change. In this Review, we discuss recent advances in the design of nanoscale stimuli-responsive systems that are able to control drug biodistribution in response to specific stimuli, either exogenous (variations in temperature, magnetic field, ultrasound intensity, light or electric pulses) or endogenous (changes in pH, enzyme concentration or redox gradients).