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Surgical site infections (SSI) are amongst the most common medical infections, occurring in 2 to 4% of patients undergoing a surgical procedure. Smart surgical sutures can play an important role in preventing infection. For example, antimicrobial sutures detectable via clinical imaging modalities can support monitoring wounds post-surgery and enhance patient recovery. However, no commercial suture products possess these properties. Herein, contrasting iodine carbon nanoparticles (ICPs) are synthesized using a solvothermal approach. These ICPs were incorporated into polycaprolactone (PCL) via a coaxial extrusion technique inspired by the "core-shell" multilayered suture structure, which integrates multiple clinically favourable functions into one suture device. This system exhibits high imaging contrast capabilities for real-time imaging even after 22 days in-vitro, with strong antimicrobial properties and a reduction in biofilm formation. The multifunctional and biocompatible suture composite developed in this study shows strong antimicrobial properties and can act as an immobilized marker to monitor the surgical site during and after surgical procedures. Identifying suture integrity and location within the body through minimally invasive methods can alleviate patient discomfort and minimize the risk of infection. publishedVersion

Hydrogels offer a unique medium for sensing applications as they can draw upon the benefits of both solid and liquid sensing platforms. Incorporation of functionalised fluorescent nanoparticles within the hydrogel matrix results in a three-dimensional nanocomposite capable of interacting with water-soluble analytes, facilitating quantitative sensing applications. Here, we report the solvothermal synthesis of a novel Polyvinylpyrrolidone assembled hydrogel stabilised with zinc oxide quantum dots which does not require additional organic crosslinkers. Functionalization of these hydrogel with novel, brightly photoluminescent 2-amino-2-methyl-1-propanol quantum carbon dots (quantum yield of 62.5%) results in a composite capable of specific interaction with hexavalent chromium. Quantitative fluorescence quenching measurements of the hydrogel composite in the presence of hexavalent chromium shows a limit of detection of 1.2 μM Cr6+ which is below maximum allowable concentrations for drinking water. The hydrogel composite is cheap to manufacture and can be injected into 96 well plates for high throughput analysis of environmental water samples. These results are encouraging for the development of hydrogels and polymetric films to be used as novel fluorescent sensing platforms for environmental diagnostic applications.

The capacity of an adsorbent to bind and remove dye from solution greatly depends on the type of functionalization present on the nanoparticles surface, and its interaction with the dye molecules. Within this study, nitrogenous silane nanoparticles were hydrothermally synthesized resulting in the formation of rapid and highly efficient adsorbents for concentrated mixed dyes. The amorphous silane nanoparticles exhibited a monolayer based mechanism of mixed dye adsorption with removal capacities between 416.67 and 714.29 mg/g of adsorbent. Dye removal was predominantly due to the electrostatic attraction between the positively charged silane nanoparticles (13.22–8.20 mV) and the negatively charged dye molecules (−54.23 mV). Addition of H. annuus extract during synthesis resulted in three times the surface area and 10 times increased pore volume compared to the positive control. XPS analysis showed that silane treatments had various nitrogen containing functionalities at their surface responsible for binding dye. The weak colloidal stability of silane particles (13.22–8.20 mV) was disrupted following dye binding, resulting in their rapid coagulation and flocculation which facilitated the separation of bound dye molecules from solution. The suitability for environmental applications using these treatments was supported by a bacterial viability assay showing >90% cell viability in treated dye supernatants.

The continued discharge of synthetic dyes into aqueous ecosystems from industrial effluent sources represents a critical issue for both human and environmental health. Although there exist various treatments for the treatment of dye-containing wastewater, a low-cost, green, effective, and ecofriendly approach still remains to be developed. In this work, carbon nanodots were synthesised using prickly pear and urea as green precursors and tested as catalysts in the Fenton-like reaction for the catalytic decolourization of cationic dyes. Approximately 90% of a mix of three common cationic dyes (crystal violet, basic fuchsin and methyl green) at 5 × 10−5 M were removed from water at 20 °C and pH 7.5 in the presence of H2O2 at 0.5% after only 60 minutes. The carbon nanodots utilised in this study were characterized by FTIR, XPS, zeta potential, UV-Vis and TEM. They exhibited negative surface charge, excellent aqueous solubility, and nitrogen rich surface functionalities which were involved in the transference of electrons, participating in the decomposition of H2O2, and therefore generated hydroxyls, superoxide ions and singlet oxygens as detected using the free radical quenching technique. This work provides an insight into exploiting an ecofriendly non-toxic metal-free catalyst using a low cost and efficient approach that showed promising decolourization results, without the use of external energy, at a neutral pH solution that could be potentially applied in catalysis of a range of environmental pollutants.

Ultrasmall nanoparticles are often grouped under the broad umbrella term of “nanoparticles” when reported in the literature. However, for biomedical applications, their small sizes give them intimate interactions with biological species and endow them with unique functional physiochemical properties. Carbon quantum dots (CQDs) are an emerging class of ultrasmall nanoparticles which have demonstrated considerable biocompatibility and have been employed as potent theragnostic platforms. These particles find application for increasing drug solubility and targeting, along with facilitating the passage of drugs across impermeable membranes (i.e., blood brain barrier). Further functionality can be triggered by various environmental conditions or external stimuli (i.e., pH, temperature, near Infrared (NIR) light, ultrasound), and their intrinsic fluorescence is valuable for diagnostic applications. The focus of this review is to shed light on the therapeutic potential of CQDs and identify how they travel through the body, reach their site of action, administer therapeutic effect, and are excreted. Investigation into their toxicity and compatibility with larger nanoparticle carriers is also examined. The future of CQDs for theragnostic applications is promising due to their multifunctional attributes and documented biocompatibility. As nanomaterial platforms become more commonplace in clinical treatments, the commercialization of CQD therapeutics is anticipated. publishedVersion

Graphical abstract, Solid or liquid platforms have been traditionally employed for measuring the fluorescent properties of quantum carbon dots (QCD). Hydrogels possess both liquid and solid properties which allow them to overcome several shortfalls of both solid and liquid sensing platforms. Hydrogels offer a three dimensional platform which can house nanoparticles with different attributes (i.e. fluorescent QCD’s) and prevents their aggregation. Here, we incorporate QCD’s (made from the hydrothermal treatment of 1-naphthylamine and citric acid) into the matrix of a zinc oxide hydrogel. This nanocomposite was shown to have hexavalent chromium (Cr6+) specific fluorescence quenching properties. Detailed fluorescence analysis of the hydrogel with Cr6+ was conducted in a high throughput manner by loading the hydrogel into wells of a black 96-well plate. Fluorescence quenching of the hydrogel-QCD-nanocomposites in the presence of dilutions of Cr6+ was measured using a fluorescence spectrophotometer and showed incremental fluorescence decreases with increasing Cr6+ concentration. Furthermore, this was quantitatively confirmed by Stern–Volmer plots showing a linear quenching trend (R2 = 0.9975) when comparing fluorescence intensities against increasing Cr6+ concentrations (0.234–1.875 μM). This technology can be applied for routine water quality testing in agricultural, natural and potable water sources for the early detection of heavy metal pollutants.

Magnesium hydroxide (Mg(OH)2) is hailed as a cheap and biocompatible material with antimicrobial potential; however, research aimed at instilling additional properties and functionality to this material is scarce. In this work, we synthesized novel, fluorescent magnesium hydroxide nanosheets (Mg(OH)2-NS) with a morphology that closely resembles that of graphene oxide. These multifunctional nanosheets were employed as a potent antimicrobial agent against several medically relevant bacterial and fungal species, particularly on solid surfaces. Their strong fluorescence signature correlates to their hydroxide makeup and can therefore be used to assess their degradation and functional antimicrobial capacity. Furthermore, their pH-responsive change in fluorescence can potentially act as a pH probe for wound acidification, which is characteristic of healthy wound healing. These fluorescent antimicrobial nanosheets were stably integrated into biocompatible electrospun fibers and agarose gels to add functionality to the material. This reinforces the suitability of the material to be used as antimicrobial bandages and gels. The biocompatibility of the Mg(OH)2-NS for topical medical applications was supported by its noncytotoxic action on human keratinocyte (HaCaT) cells.

Carbon quantum dots (CQD) are fluorescent nanoparticles that show potential in bioimaging as biocompatible fluorescent dye replacements. Even though numerous precursors and various fabrication processes are reported, the use of corrosive chemicals is widespread during most of the process. Recently, researchers have focused on green synthesis techniques for CQDs used in biological studies. In this work, we report on CQDs fabricated from prevalent carbon sources, namely paper and bread, using a facile chemical-free technique. This green synthetic route facilitated the production of luminescent CQDs with a broad emission range between 380 – 600 nm. The photoluminescence of the CQDs was analyzed, and a suitable candidate for bioimaging was identified. The CQDs obtained from bread exhibited comparatively high fluorescent and low cytotoxicity. Moreover, these CQDs were well internalized by C2C12 muscle myoblast cells and clearly luminescent in differentiated myotubes. The results will potentially aid in disease and intervention studies using C2C12 cell model systems.

Heavy metal contamination is a major global concern and additive toxicity resulting from the exposure to multiple heavy metal ions is more pronounced than that induced by a single metal species. Quantum dots (QDs) have demonstrated unique properties as sensing materials for heavy metal ions over the past two decades. With the rapid development and deep understanding on determination of single heavy metal ion using QD probes, this technology has been employed for sensing multiple metal ions. This review (with 97 refs.) summarizes the progress made in recent years in methods for multiplexed determination of heavy metal ions using QDs. Following an introduction into the importance of simultaneous quantitation of multiple heavy metal ions in environmentally relevant settings, the review discusses the applications of different types of QDs, i.e. chalcogenide, carbon, polymer and graphene in this field. Determination strategies based on fluorometric, colorimetric and electrochemical responses were reviewed including the testing mechanisms and differentiation between various metal ions. In addition, current state of the art sensor constructions, i.e. immobilization of QDs on solid substrate and sensor arrays have been highlighted. A concluding section describes the limitations, opportunities and future challenges of the QD probes. We also compiled a comprehensive table of currently available literature. The listed papers provided information in the following categories, i.e. type of QDs used, ligands or other components in the probe, metal ions tested, medium/substrate of the probe, transduction methods, discrimination mechanism, limit of detection (LOD) and concentration range. Graphic abstract.

Hexavalent chromium is a genotoxic and carcinogenic byproduct of a number of industrial processes, which is discharged into the environment in excessive and toxic concentrations worldwide. In this paper, the synthesis of green iron oxide nanoparticles using extracts of four novel plant species [Pittosporum undulatum, Melia azedarach, Schinus molle, and Syzygium paniculatum (var. australe)] using a "bottom-up approach" has been implemented for hexavalent chromium remediation. Nanoparticle characterizations show that different plant extracts lead to the formation of nanoparticles with different sizes, agglomeration tendencies, and shapes but similar amorphous nature and elemental makeup. Hexavalent chromium removal is linked with the particle size and monodispersity. Nanoparticles with sizes between 5 and 15 nm from M. azedarach and P. undulatum showed enhanced chromium removal capacities (84.1-96.2%, respectively) when compared to the agglomerated particles of S. molle and S. paniculatum with sizes between 30 and 100 nm (43.7-58.7%, respectively) in over 9 h. This study has shown that the reduction of iron salts with plant extracts is unlikely to generate vast quantities of stable zero valent iron nanoparticles but rather favor the formation of iron oxide nanoparticles. In addition, plant extracts with higher antioxidant concentrations may not produce nanoparticles with morphologies optimal for pollutant remediation.

Urban soils in many communities in the United States and internationally have been contaminated by lead (Pb) from past use of lead additives in gasoline, deterioration of exterior paint, emissions from Pb smelters and battery recycling and other industries. Exposure to Pb in soil and related dust is widespread in many inner city areas. Up to 20–40% of urban children in some neighborhoods have blood lead levels (BLLs) equal to or above 5 μg per decilitre, the reference level of health concern by the U.S. Centers for Disease Control. Given the widespread nature of Pb contamination in urban soils it has proven a challenge to reduce exposure. In order to prevent this exposure, an evidence-based approach is required to isolate or remediate the soils and prevent children and adult's ongoing exposure. To date, the majority of community soil Pb remediation efforts have been focused in mining towns or in discrete neighborhoods where Pb smelters have impacted communities. These efforts have usually entailed very expensive dig and dump soil Pb remediation techniques, funded by the point source polluters. Remediating widespread non-point source urban soil contamination using this approach is neither economical nor feasible from a practical standpoint. Despite the need to remediate/isolate urban soils in inner city areas, no deliberate, large scale, cost effective Pb remediation schemes have been implemented to isolate inner city soils impacted from sources other than mines and smelters. However, a city-wide natural experiment of flooding in New Orleans by Hurricane Katrina demonstrated that declines in soil Pb resulted in major BLL reductions. Also a growing body of literature of smaller scale pilot studies and programs does exist regarding low cost efforts to isolate Pb contaminated urban soils. This paper reviews the literature regarding the effectiveness of soil Pb remediation for reducing Pb exposure and BLL in children, and suggests best practices for addressing the epidemics of low-level Pb poisoning occurring in many inner city areas.

Phenol-formaldehyde plastics are used globally as floral foam and generate microplastics that can enter the environment. This study is the first to describe how aquatic animals interact with this type of microplastic, and the resultant physiological responses. We analysed “regular foam” microplastics generated from petroleum-derived phenol-formaldehyde plastic, and “biofoam” microplastics generated from plant-derived phenol-formaldehyde plastic. Regular foam and biofoam microplastics showed similar FTIR spectra. Both types of microplastics were consumed by all six invertebrate species tested: the freshwater gastropod Physa acuta, the marine gastropod Bembicium nanum, the marine bivalve Mytilus galloprovincialis, adults and neonates of the freshwater crustacean Daphnia magna, the marine amphipod Allorchestes compressa, and nauplii of the marine crustacean Artemia sp. For all species, the occurrence of ingestion was similar for regular foam and biofoam microplastics. Biofoam microplastics leached more than twice as much phenolic compounds than regular foam microplastics. The leachates from regular foam and biofoam microplastics showed the same acute toxicity to Artemia nauplii (24-h LC50 = 27.4 mg mL−1 and 22.8 mg mL−1, respectively) and D. magna (48-h LC50 = 17.8 mg mL−1 and 15.3 mg mL−1, respectively). However, biofoam microplastic leachate was twice as toxic to embryos of the zebrafish, Danio rerio, compared with leachate from regular foam microplastic (96-h LC50 = 43.8 mg mL−1 vs 27.1 mg mL−1). Using M. galloprovincialis, we show that regular foam microplastic leachate and the physical presence of the microplastics exerted separate and cumulative effects on catalase (CAT) activity, glutathione-s-transferase (GST) activity and lipid peroxidation. Microplastic ingestion did not affect the activity of acetylcholinesterase (AChE). Taken together, these results show that phenol-formaldehyde microplastics can interact with a range of aquatic animals, and affect sublethal endpoints by leaching toxic compounds, and through the physical presence of the microplastics themselves.

Environmental harm caused by the release of textile dye contaminated wastewater from industry is an issue that requires immediate attention, particularly in developing countries. We herein demonstrate that green tea derived amorphous iron nanoparticles, in conjunction with Fenton like chemical processes, catabolise anthraquinone and azo dye mixtures that constitute a significant proportion of industrial dye waste. Iron nanoparticles, synthesized following a green tea mediated greener synthesis approach were able to degrade concentrated dye mixtures with over 90% decolourisation in only 20 min with 0.53 ppm nanoparticle concentration at a temperature of 70 °C. Detailed experimental degradation efficiencies were significantly pH and temperature dependant favouring lower pH values at temperatures between 70 and 90 °C, conditions which are commonly found in textile wastewaters. This research has shown the capacity for green tea synthesized nanoparticles to be used as a promoter for Fenton like dye degradation reactions. This rapid treatment approach may gain interest in the textile industries for dye waste remediation.

Nanotechnology is playing an increasingly important role in addressing innovative and effective solutions to a vast range of environmental challenges. In recent years, nanoscale zero valent iron (nZVI), carbon nanotubes and nano-fibers have been applied for the remediation of a variety of contaminants including chlorinated compounds, hydrocarbons, organic compounds and heavy metals. The use and development of nanomaterials (NMs) are understandably heralded as an environmentally beneficial technology; however the ecological risks associated with their use have only begun to be assessed. This critical review highlights (i) the successful applications of nanotechnology for environmental clean-up, (ii) the potential ecological implications of environmental nanotechnology (E-Nano) involving use of nanomaterials and (iii) the potential solutions to current E-Nano related implications. Although there is undoubtedly cause for concerns among the scientific community over nanotechnology risk management, the efficacy of E-Nano is unquestionable. Hence, to advance this field in a rational manner without causing further environmental damage, we suggest an integrated preventive approach. This includes innovative greener routes for nanoparticle synthesis; advanced engineering ways for manufacturing smarter and more degradable NMs; and governing local and international legislations to monitor nanoparticles released into the environment. The aims of these recommendations is to promote the responsible innovation of NMs and its cautious use in order to take optimal advantage of E-Nano, minimizing potential risks which is a crucial aspect to improve environmental quality rather than to cause additional damage.

Biocompatible carbon quantum dots (CQDs) have recently attracted increased interest in biomedical imaging owing to their advantageous photoluminescence properties. Numerous precursors of fluorescent CQDs and various fabrication procedures are also reported in the literature. However, the use of concentrated mineral acids and other corrosive chemicals during the fabrication process curtails their biocompatibility and severely limits the utilization of the products in cell bio-imaging. In this study, a facile, fast, and cost-effective synthetic route is employed to fabricate CQDs from a natural organic resource, namely bread, where the use of any toxic chemicals is eliminated. Thus, the novel chemical-free technique facilitated the production of luminescent CQDs that were endowed with low cytotoxicity and, therefore, suitable candidates for bioimaging sensors. The above mentioned amorphous CQDs also exhibited fluorescence over 360&ndash, 420 nm excitation wavelengths, and with a broad emission range of 360&ndash, 600 nm. We have also shown that the CQDs were well internalized by muscle myoblasts (C2C12) and differentiated myotubes, the cell lines which have not been reported before.

The current chapter is aimed at outlining the current research relating to generating iron nanoparticles for the use within contaminated site remediation. Synthesis, characterization, coatings to facilitate movement and factors affecting nanoparticle reactivity will be discussed. Furthermore, their current use, efficiency and potential toxicity to the environment will have a focus. This chapter provides a brief overview on the current status of iron nanoparticle mediated environmental remediation. Catabolism of a vast array of different anthropogenic pollutant classes are possible with iron nanoparticles including heavy metals, nitrogen, pesticides, dyes, chlorinated solvents, hydrocarbons and inorganic ions to name a few. This chapter is targeted towards beginners and established environmental science researchers alike who will have limited understanding in the field of nanoremiediation employing Iron nanoparticles.

Polyaromatic hydrocarbons (PAHs) represent a fraction of petroleum hydrocarbons and are currently one of the foremost sources of generating energy in today’s contemporary society. However, evidence highlighted in this review show that PAH pollution, as a result of oil spills, hazardous PAH-contaminated working environments and technologies which do not efficiently utilise fuels, as well as natural sources of emissions (e.g. forest fires) may have significant health implications for all taxa. The extent of damage to organisms from PAH exposure is dependent on numerous factors including degree and type of PAH exposure, nature of the environment contaminated (i.e. terrestrial or aquatic), the ability of an organism to relocate to pristine environments, type and sensitivity of organism to specific hydrocarbon fractions and ability of the organism to metabolise different PAH fractions. The review highlights the fact that studies on the potential damage of PAHs should be carried out using mixtures of hydrocarbons as opposed to individual hydrocarbon fractions due to the scarcity of individual fractions being a sole contaminant. Furthermore, potential damage of PAH-contaminated sites should be assessed using an entire ecological impact outlook of the affected area.