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Photo-inactivation and efflux pump inhibition of methicillin resistant Staphylococcus aureus using thiolated cobalt doped ZnO nanoparticles
摘要： Multidrug resistance (MDR) in bacteria is a major concern these days. One of the reasons is the mutation in efflux pump that prevents the retention of antibiotics and drugs in the bacterial cell. The current work is a step to overcome MDR in bacteria via inhibition of efflux pump and further photoinhibition by thiolated chitosan coated cobalt doped zinc oxide nanoparticles (Co-ZnO) in visible light. Co-ZnO were synthesized in a size range of 40–60 nm. Antibacterial activity of the Co-ZnO against methicillin resistant Staphylococcus aureus (MRSA) was found 100% at a concentration of 10 μg/ml upon activation in sunlight for 15 min. Interestingly, it was found that cobalt as a dopant was able to increase the photodynamic and photothermal activity of Co-ZnO, as in dark conditions, there was only 3–5% of inhibition at 10 μg/ml of nanoparticle concentration. Upon excitation in light, these nanoparticles were able to generate reactive oxygen species (ROS) with a quantum yield of 0.23 ± 0.034. The nanoparticles were also generating heat, Because of the magnetic nature, thus helping in more killing. Thiolated chitosan further helped in blocking the efflux pump of MRSA. The current nanoparticles were also found biocompatible on human red blood cells (LD50 = 214 μg/ml). These data suggest that the MRSA killing ability was facilitated through efflux inhibition and oxidative stress upon excitation in visible light hence, were in accordance with previous findings.
关键词： Multidrug resistant bacteria,Biocompatibility,ZnO nanoparticles,Photo-inactivation,ROS,MRSA
更新于2025-09-19 17:15:36
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A novel aspect of functionalized graphene quantum dots in cytotoxicity studies
摘要： Graphene quantum dots (GQDs) represent a new generation of graphene-based nanomaterials with enormous potential for use and development of a variety of biomedical applications. However, up to now little studies have investigated the impact of GQDs on human health in case of exposure. GQDs were synthesized from citric acid as carbon precursor by hydrothermal treatment at 160 °C for 4 h. The synthesized GQDs showed strong blue emission under UV-Irradiation with fluorescence quantum yield of 9.8%. The obtained GQDs were further functionalized by nitric acid vapor method. Nitrogen carbonized, activated and adsorption/desorption isotherms were used to analyze the surface area and porous structures of GQDs. The results revealed that compared to GQDs, the specific surface area of functionalized graphene quantum dots (fGQDs) has been increased from 0.0667 to 2.5747 m2/g and pore structures have been enhanced significantly. The potential cytotoxic effect of GQDs, fGQDs and GO suspensions was evaluated on HFF cell line using MTT assays and flow cytometry method after 24 h incubation. We have for the first time demonstrated that by carbonization, activation and functionalization of GQDs they still showed cytocompatible properties. We observed excellent biocompatibility of GQDs and fGQDs at low concentrations. Moreover, the results suggested that modification of GQDs yields product suspensions with high surface area, enhanced pore volume and loading capacities. Thus, fGQDs represent an attractive candidate for further use in drug delivery systems and bio-imaging application.
关键词： Graphene quantum dot,Biocompatibility,Cytotoxicity,Flow cytometry,Functionalized graphene quantum dot
更新于2025-09-19 17:13:59
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Highly biocompatible graphene quantum dots: green synthesis, toxicity comparison and fluorescence imaging
摘要： Graphene quantum dots (GQDs) have tremendous potential in biological imaging due to their bright visible photoluminescence mission. However, the tedious preparation procedures and potential toxicity of GQDs greatly limit their application in biological field. Here, highly biocompatible GQDs (HGQDs) have been successfully prepared only by glucose in aqueous solution. Compared with GQDs prepared from conventional methods (CGQDs), the cytotoxicity of HGQDs reduced by more than 60%, and the flow cytometric analysis of the normal cells treated with HGQDs showed that the early and late apoptotic rate reduced by more than 72% and 40%, respectively. In vitro fluorescence imaging showed that both cells and bacteria could be imaged by HGQDs, and the morphology of cells and bacteria could be kept to a maximum extent. A long-term in vivo study revealed that no obvious organ (heart, liver, spleen, lung and kidney) damage or lesions were observed, and the blood–brain barrier (BBB) could be overcome, which provides the possibility for treatment and diagnosis of brain-related diseases. With adequate studies of biocompatibility, both in vitro and in vivo, HGQDs may be considered for further biological application.
关键词： biocompatibility,biological application,fluorescence imaging,Graphene quantum dots
更新于2025-09-19 17:13:59
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Fluorine-containing graphene quantum dots with a high singlet oxygen generation applied for photodynamic therapy
摘要： Recently, graphene quantum dots (GQDs) have been extensively studied in biomedical areas such as bio-imaging, bio-sensing and photothermal therapy due to their superior optical and physiochemical properties compared to traditional organic biomarkers. Application of GQDs in photodynamic therapy (PDT) has been explored since 2014, but currently the main challenges are inadequate singlet oxygen (1O2) quantum yield (QY), poor solubility and biocompatibility. Herein, we report on the synthesis of a new kind of fluorine-containing GQDs (F-GQDs) by an oxidative cutting method using fluorinated graphite as the raw material. The as-synthesized F-GQDs sample demonstrates an average particle size of 2.1 nm with the fluorine doping content of 1.43%. The F-GQDs have a more excellent water solubility and biocompatibility than the GQDs, and emit strong green fluorescence at 365 nm excitation with the relative fluorescence QY of 13.72%. Moreover, the fluorescence imaging effect as well as photodynamic activity successfully tested in both in vitro HepG2 cell line model and a 3D multicellular spheroids model that mimics the tumour microenvironment. Further studies using UV-visible spectroscopy through the degradation of water-soluble 9,10-anthracenediyl-bis(methylene) dimalonic acid(ABDA) demonstrate that the F-GQDs sample generate 1O2 efficiently (QY = 0.49) under a visible light irradiation. Compared to non-fluorinated GQDs, the as-reported F-GQDs manifest to be a more promising photosensitizer for image-guided PDT.
关键词： singlet oxygen,photodynamic therapy,biocompatibility,fluorine-containing,graphene quantum dots
更新于2025-09-19 17:13:59
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In Vitro Bioactivity and Biocompatibility of Bio-Inspired Ti-6Al-4V Alloy Surfaces Modified by Combined Laser Micro/Nano Structuring
摘要： The bioactivity and biocompatibility play key roles in the success of dental and orthopaedic implants. Although most commercial implant systems use various surface microstructures, the ideal multi-scale topographies capable of controlling osteointegration have not yielded conclusive results. Inspired by both the isotropic adhesion of the skin structures in tree frog toe pads and the anisotropic adhesion of the corrugated ridges on the scales of Morpho butter?y wings, composite micro/nano-structures, including the array of micro-hexagons and oriented nano-ripples on titanium alloy implants, were respectively fabricated by microsecond laser direct writing and femtosecond laser-induced periodic surface structures, to improve cell adherence, alignment and proliferation on implants. The main di?erences in both the bioactivity in simulated body ?uid and the biocompatibility in osteoblastic cell MC3T3 proliferation were measured and analyzed among Ti-6Al-4V samples with smooth surface, micro-hexagons and composite micro/nano-structures, respectively. Of note, bioinspired micro/nano-structures displayed the best bioactivity and biocompatibility after in vitro experiments, and meanwhile, the nano-ripples were able to induce cellular alignment within the micro-hexagons. The reasons for these di?erences were found in the topographical cues. An innovative functionalization strategy of controlling the osteointegration on titanium alloy implants is proposed using the composite micro/nano-structures, which is meaningful in various regenerative medicine applications and implant ?elds.
关键词： bioinspired surfaces,biocompatibility,cell adherence,femtosecond laser,bioactivity,cell alignment,Ti-6Al-4V,LIPSS
更新于2025-09-19 17:13:59
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Laser Polishing of Ti6Al4V Fabricated by Selective Laser Melting
摘要： Selective laser melting (SLM) is emerging as a promising 3D printing method for orthopedic and dental applications. However, SLM-based Ti6Al4V components frequently exhibit high roughness values and partial surface defects. Laser polishing (LP) is a newly developed technology to improve the surface quality of metals. In this research, LP is applied to improve the surface ?nish of components. The results show that the laser beam can neatly ablate the aggregates of metallic globules and repair cracks and pores on the surface, resulting in a smooth surface with nanocomposites. Overall, the results indicate that using LP optimizes surface morphology to favor fatigue behavior and osteoblastic di?erentiation. These ?ndings provide foundational data to improve the surface roughness of a laser-polished implant and pave the way for optimized mechanical behavior and biocompatibility via the laser process.
关键词： laser polishing,additive manufacturing,biocompatibility,mechanical properties,surface roughness
更新于2025-09-19 17:13:59
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Controlled synthesis and photocatalytic performance of biocompatible uniform carbon quantum dots with microwave absorption capacity
摘要： Carbon quantum dots (CQDs) were successfully prepared via a facile microwave-assisted method combined with a controlled drainage time using glucose as the carbon source. XRD analysis, FT-IR spectroscopy, UV spectroscopy, XPS, and PL spectroscopy were performed to characterize the structures and properties of the samples. The results showed that the average particle size of the prepared CQDs was about 2 nm, and there were two UV absorption at the wavelengths of 228 nm and 280 nm, respectively, corresponding to the π-π* transition of C=C (atomic group) and the n-π* transition of the oxygen containing group (C=O) on the surface of the carbon core. According to the unique optical and microwave absorption properties of the CQDs, a suitable photocatalytic system, namely, a microwave electrodeless discharge lamp (MEDL) system was used. In the MEDL system, the degradation rate of rhodamine B (RhB, 50mL, 30 mg L-1) by 0.02 g CQDs-2 in 10 min could reach 85.79 %. The photocatalytic activity of CQDs-2 was about twice that of P25. In addition, the biocompatibility of the CQDs was investigated, which revealed that the CQDs could be absorbed by microorganisms as a carbon source. The prepared CQDs are a promising environmentally friendly photocatalyst.
关键词： biocompatibility,microwave,photocatalytic,CQDs
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Investigation of Photoluminescence Properties of 2D-Nanoparticles to be Used as Fluorescence Markers in Microscopy
摘要： Transition metal dichalcogenides (TMDs) are direct bandgap semiconductors [1], and they exhibit fascinating optical properties, such as valley polarization, room temperature excitons, and high optical nonlinearity. Single and few-layer TMDs and TMD-nanoparticles exhibit much stronger photoluminescence than the bulk material [2]. This property makes them an attractive candidate for use as mesoscale fluorescent markers, e.g., for use in fluorescence microscopy. As opposed to conventional fluorescent markers, such as fluorescent molecules they do not exhibit phototoxicity and have been shown to be biocompatible in contrast to, e.g., many types of quantum dots. Here we focus on the characterization of MoS2 and WS2 nanoparticles, obtained through liquid phase exfoliation [3], from powdered precursors. Sonication of TMD powder in N-Methyl pyrrolidone (NMP) is carried out, as NMP and single layer TMDs have comparable surface energies to prevent the restacking of exfoliated nanosheets. The resulting solution was found to have particles of a typical size of 65 nm, which have been investigated for PL-spectra and long-term PL-behaviour, such as blinking and bleaching. Structural analysis reveals (See Fig.1 (a)) that we have a mixture of particles and particle agglomerates. PL spectra show that both exhibit comparable spectral signatures with peak wavelengths (Fig. 1(b)) ranging from 600 to 640nm. The excitation wavelength was 532nm. We find that these results indicate, that TMD-nanoparticles are suitable, e.g., for use as fluorescent guide stars [4] in adaptive optical microscopy in inhomogeneous samples, e.g., tissue. 2D-nanoparticles would be infiltrated into the sample, and the PL-emission could be used by a combination of a wavefront-sensor and an adaptive optical element to undo the effects of scattering in the vicinity of the particle. This method would leverage the strong PL, biocompatibility and long-term stability of the 2D-nanoparticles, to allow for longer observation cycles in sensitive samples, such as living tissue.
关键词： nanoparticles,photoluminescence,biocompatibility,fluorescence microscopy,Transition metal dichalcogenides
更新于2025-09-16 10:30:52
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Revisiting the cytotoxicity of quantum dots: an in-depth overview
摘要： Recently, medical research has been shifting its focus to nanomedicine and nanotherapeutics in the pursuit of drug development research. Quantum dots (QDs) are a critical class of nanomaterials due to their unique properties, which include optical, electronic, and engineered biocompatibility in physiological environments. These properties have made QDs an attractive biomedical resource such that they have found application as both in vitro labeling and in vivo theranostic (therapy-diagnostic) agents. Considerable research has been conducted exploring the suitability of QDs in theranostic applications, but the cytotoxicity of QDs remains an obstacle. Several types of QDs have been investigated over the past decades, which may be suitable for use in biomedical applications if the barrier of cytotoxicity can be resolved. This review attempts to report and analyze the cytotoxicity of the major QDs along with relevant related aspects.
关键词： Theranostic agents,Quantum dots,Biocompatibility,Cytotoxicity,Biomedical applications
更新于2025-09-16 10:30:52
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Facile, large scale synthesis of water soluble AgInSe2/ZnSe quantum dots and its cell viability assessment on different cell lines
摘要： I-III-VI chalcopyrite ternary quantum dots have emerged as a good alternative over the conventional II-VI and IV-VI chalcogenide binary QDs that usually consist of heavy metals such as Cd and Pb which has limited their bioapplications. Among the chalcopyrite QDs, AgInSe2 QDs has been the least developed due to the imbalanced cation reactivity, unwanted impurities, broad size distribution and resultant large particle sizes. In addition, the cell viability of these QDs still needs to be investigated on different cell lines both normal and cancerous ones. Herein, large-scale synthesis of water-soluble thioglycolic acid (TGA) capped and gelatin-stabilized AgInSe2 (AISe) core and AgInSe2/ZnSe (AISe/ZnSe) core/shell QDs in the absence of an inert atmosphere and their cell viability against different cell lines are reported. The optical and structural characteristics of the as-synthesized QDs were investigated by UV–visible (vis) absorption, photoluminescence (PL) and Fourier-transmission infrared (FTIR) spectroscopies, dynamic light scattering (DLS), X-ray diffraction (XRD), and high-resolution transmission electron microscope (HRTEM) techniques. Growth of ZnSe shell on the core AISe resulted in the blue shifting of the emission maximum position with the increased PL intensity. The QDs are small and spherical in shape with an average particle diameter of 2.8 nm and 3.2 nm for AISe and AISe/ZnSe QDs respectively. The in vitro cell viability assay revealed that the as-synthesized AISe/ZnSe QDs are not toxic towards cancerous (HeLa -cervical cancer and A549-lung cancer) and normal (BHK21 –Kidney) cell lines.
关键词： I-III-VI quantum dots,Cell viability,AgInSe2/ZnSe,Biocompatibility
更新于2025-09-12 10:27:22