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Colloidally Stable Monolayer Nanosheets with Colorimetric Responses
摘要： Despite the discovery of chromogenic-layered materials for decades of years, fabrication of colloidally stable monolayer organic 2D nanosheets in aqueous media with colorimetric responses is still challenging. Herein reported is the first solution synthesis of chromic monolayer nanosheets via the topochemical polymerization of self-assembled amphiphilic diacetylenes in aqueous media. The polydiacetylene (PDA) nanosheets are ≈3–4 nm thick in solution and only ≈1.9 nm thick in the dried state, while the lateral size can reach several micrometers. Moreover, the aqueous stability endows PDA nanosheets with excellent processability, which can further assemble into films via vacuum filtration or act as an ink for high-resolution inkjet printing. The filtrated films and printed patterns exhibit fully reversible blue-to-red thermochromism, and the film also displays an interesting reversible colorimetric transition in response to near-infrared light, which is not reported for other PDA-only systems. The present colloidal PDA nanosheets should represent a new kind of chromic organic 2D nanomaterials that may be applied as novel building blocks for developing intelligent hybrid materials and may also find diverse sensing, display and/or anticounterfeiting applications.
关键词： colorimetric responses,monolayer nanosheets,colloidal stability,polydiacetylene
更新于2025-09-23 15:23:52
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Biocompatible superparamagnetic core-shell nanoparticles for potential use in hyperthermia-enabled drug release and as an enhanced contrast agent
摘要： Superparamagnetic iron oxide nanoparticles (SPIONs) and core-shell type nanoparticles, consisting of SPIONs coated with mesoporous silica and/or lipid, were synthesized and tested for their potential theranostic applications in drug delivery, magnetic hyperthermia and as a contrast agent. Transmission Electron Microscopy (TEM) confirmed the size of bare and coated SPIONs was in the range of 5-20 nm and 100-200 nm respectively. The superparamagnetic nature of all the prepared nanomaterials as indicated by Vibrating Sample Magnetometry (VSM) and their heating properties under an AC field confirm their potential for hyperthermia applications. Scanning Column Magnetometry (SCM) data showed that extrusion of bare-SPION (b-SPION) dispersions through a 100 nm polycarbonate membrane significantly improved the dispersion stability of the sample. No sedimentation was apparent after 18 hours compared to a pre-extrusion estimate of 43% settled at the bottom of the tube over the same time. Lipid coating also enhanced dispersion stability. Transversal relaxation time (T2) measurements for the nanoparticles, using a bench-top relaxometer, displayed a significantly lower value of 46 ms, with a narrow relaxation time distribution, for lipid silica coated SPIONs (Lip-SiSPIONs) as compared to that of 1316 ms for the b-SPIONs. Entrapment efficiency of the anticancer drug, Doxorubicin (DOX) for Lip-SPIONs was observed to be 35% which increased to 58% for Lip-SiSPIONs. Moreover, initial in-vitro cytotoxicity studies against human breast adenocarcinoma, MCF-7 cells showed that % cell viability increased from 57% for bSPIONs to 82% for Lip-SPIONs and to 87% for Lip-SiSPIONs. This suggests that silica and lipid coatings improve the biocompatibility of bSPIONs significantly and enhance the suitability of these particles as drug carriers. Hence, the magnetic nanomaterials prepared in this work have potential theranostic properties as a drug carrier for hyperthermia cancer therapy and also offer enhancement of contrast agent efficacy and a route to a significant increase in dispersion stability.
关键词： magnetoliposomes,drug carrier,cancer therapy,colloidal stability,hyperthermia,theranostic,Superparamagnetic iron oxide nanoparticles
更新于2025-09-23 15:21:01
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Dextran-Functionalized Semiconductor Quantum Dot Bioconjugates for Bioanalysis and Imaging
摘要： The prerequisites for maximizing the advantageous optical properties of colloidal semiconductor quantum dots (QDs) in biological applications are effective surface functionalization and bioconjugation strategies. Functionalization with dextran has been highly successful with some nanoparticle materials, but has had very limited application with QDs. Here, we report the preparation, characterization, and proof-of-concept applications of dextran-functionalized QDs. Multiple approaches to dextran ligands were evaluated, including performance with respect to colloidal stability across a range of pH, nonspecific binding with proteins and cells, and microinjection into cells and viability assays. Multiple bioconjugation strategies were demonstrated and applied, including covalent coupling to develop a simple pH sensor, binding of polyhistidine-tagged peptides to the QD for energy transfer-based proteolytic activity assays, and binding with tetrameric antibody complexes (TACs) to enable a sandwich immunoassay and cell immunolabeling and imaging. Our results show that dextran ligands are highly promising for the functionalization of QDs, and that the design of the ligands is tailorable to help optimally meet the requirements of applications.
关键词： dextran,quantum dots,colloidal stability,imaging,bioconjugation,bioanalysis
更新于2025-09-23 15:19:57
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Exploring the surface chemistry of cesium lead halide perovskite nanocrystals
摘要： Colloidal nanocrystals (NCs) of cesium lead halide perovskites (CsPbX3, X = Cl, Br or I) are emerging as an exciting class of optoelectronic materials, but the retention of their colloidal and structural integrity during isolation, purification and handling still represents a critical issue. The impelling questions concerning their intrinsic chemical instability are connected to the dynamic nature of the bonding between the inorganic surface and the long-chain capping ligands. However, the key aspects of CsPbX3's surface chemistry that directly impact their stability remain elusive. In this contribution, we provide an in-depth investigation of the surface properties of differently composed CsPbX3 NCs, prepared by traditional hot-injection methods. The study, mainly relying on solution NMR spectroscopy, is backed up by elemental analysis as well as morphological, structural and optical investigations. We ascertained that the nature of the ligand adsorption/desorption processes at the NC surface is dependent on its elemental composition, thus explaining the origin of the instability afflicting CsPbI3 NCs. We also evaluated the effect of NC purification as well as of the degradation pathways involving the organic shell on the surface chemistry of CsPbX3 NCs. This study paves the way for new post-functionalization strategies for this promising class of nanomaterials.
关键词： surface chemistry,colloidal stability,degradation pathways,cesium lead halide perovskite nanocrystals,purification,ligand adsorption/desorption,NMR spectroscopy
更新于2025-09-19 17:15:36
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Natural organic matter inhibits aggregation of few-layered black phosphorus in mono- and divalent electrolyte solutions
摘要： Extensive synthesis and applications of few-layered black phosphorus (BPs) are accompanied by increasing concern over its stability and potential risk. However, the colloidal stability of BPs under environmentally relevant conditions remains unclear. Hence, we investigated the influences of two representative electrolytes (i.e., NaCl and CaCl2) and natural organic matter (NOM) on the aggregation behavior of BPs. Ca2+ ions exhibited a stronger destabilization effect on BPs than Na+ due to their stronger surface charge screening as well as intersheet bridging by the complexes of Ca2+ ions and oxidized phosphorus (POx) species on the BPs surface. Apart from the Ca2+-induced enhanced aggregation in the presence of high concentration of Ca2+, the aggregation behavior of BPs in the two electrolytes at different concentrations and their ratios of critical coagulation concentrations (CCCs) generally followed classical colloidal theory such as the Schulze–Hardy rule. Moreover, in the presence of 10 mg C/L NOM the CCC values of BPs in NaCl and CaCl2 solutions were both three times higher than that obtained without NOM, and the aggregation kinetics of BPs in these electrolytes containing NOM were qualitatively consistent with extended DLVO theory. Specifically, NOM significantly improved the stabilization of BPs in CaCl2 solutions via steric repulsion and isolation of Ca2+ ions from interaction with POx species on the surface of BPs. This stabilization mechanism derived from “NOM corona” structures was elucidated by a wide spectrum of characterization and quantification techniques. These findings provide new insights into evaluating the stability and fate of this nanomaterial in natural aquatic environments.
关键词： few-layered black phosphorus,colloidal stability,NOM corona,aggregation,electrolytes,natural organic matter
更新于2025-09-19 17:15:36
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A Robust and General Approach to Quantitatively Conjugate Enzymes to Plasmonic Nanoparticles
摘要： Bioconjugates of plasmonic nanoparticles have received considerable attention due to their potential biomedical applications. Succesfull bioconjugation requires control over the number and activity of the conjugated proteins, and the colloidal stability of the particles. In practice, this requires re-optimization of the conjugation protocol for each combination of protein and nanoparticle. Here we report a robust and general protocol that allows for the conjugation of a range of proteins to di?erent types of nanoparticles using very short polyethylene-glycol(PEG) linkers, while simultaneously preserving protein activity and colloidal stability. The use of short linkers ensures that the protein is located close to the particle surface, where their refractive index sensitivity and near-?eld enhancement is maximal. We demonstrate that the use a Tween20 containing stabilizing bu?er is critical in maintaining colloidal stability and protein function throughout the protocol. We obtain quantitative control over the average number of enzymes per particle by either varying the number of functional groups on the particle, or the enzyme concentration during incubation. This new route of preparing quantitative protein-nanoparticle bioconjugates paves the way to develop rational and quantitative strategies to functionalize nanoparticles for applications in sensing, medical diagnostics and drug delivery.
关键词： medical diagnostics,drug delivery,quantitative control,protein activity,plasmonic nanoparticles,colloidal stability,sensing,bioconjugation,PEG linkers,Tween20
更新于2025-09-12 10:27:22
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Quantum dot cellular uptake and toxicity in the developing brain: implications for use as imaging probes
摘要： Nanometer-sized luminescent semiconductor quantum dots (QDs) have been utilized as imaging and therapeutic agents in a variety of disease settings, including diseases of the central nervous system. QDs have several advantages over traditional fluorescent probes including their small size (5–10 nm), tunable excitation and emission spectra, tailorable surface functionality, efficient photoluminescence, and robust photostability, which are ideal characteristics for in vivo imaging. Although QDs are promising imaging agents in brain-related applications, no systematic evaluation of QD behavior in brain-relevant conditions has yet been done. Therefore, we sought to investigate QD colloidal stability, cellular uptake, and toxicity in vitro, ex vivo, and in vivo in the brain environment. We found that QD behavior is highly dependent on surface functionality and that treatment of cultured organotypic whole hemisphere (OWH) slices with QDs results in dose-dependent toxicity and metallothionein increase, but no subsequent mRNA expression level changes in inflammatory cytokines or other oxidative stress. QDs coated with poly(ethylene glycol) (PEG) were protected from aggregation in neurophysiologically relevant fluids and allowed for greater penetration in tissue. Importantly, QD behavior differed in cultured slices as compared to monolayer cell cultures, and behavior in cultured slices aligned more closely with that seen in vivo. Irrespective of surface chemistry and brain-relevant platform, non-aggregated QDs were primarily internalized by microglia in a region-dependent manner both in slices and in vivo upon systemic administration. This knowledge will help guide further engineering of candidate QD-based imaging probes for neurological application.
关键词： brain,imaging probes,quantum dots,colloidal stability,cellular uptake,toxicity
更新于2025-09-11 14:15:04
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ZnO nanocrystals shuttled by extracellular vesicles as effective Trojan nano-horses against cancer cells
摘要： The effective application of nanoparticles in cancer theranostics is jeopardized by their aggregation in biological media, rapid degradation and clearance. The design of biomimetic nanoconstructs with enhanced colloidal stability and non-immunogenicity is therefore essential. We propose naturally stable cell-derived extracellular vesicles to encapsulate zinc oxide (ZnO) nanocrystals as efficacious nanodrugs, to obtain highly biomimetic and stable Trojan nano-horses (TNHs). Materials & methods: Coupling efficiency, biostability, cellular cytotoxicity and internalization were tested. Results: In vitro studies showed a high internalization of TNHs into cancer cells and efficient cytotoxic activity thanks to ZnO intracellular release. Conclusion: TNHs represent an efficient biomimetic platform for future nanotheranostic applications, with biomimetic extracellular vesicle-lipid envelope, facilitated ZnO cellular uptake and potential therapeutic implications.
关键词： biomimetics,extracellular vesicles,colloidal stability,cytotoxicity,nanocrystals,zinc oxide
更新于2025-09-11 14:15:04
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A high-resolution study of in situ surface-enhanced Raman scattering nanotag behavior in biological systems
摘要： The colloidal stability of surface-enhanced Raman scattering (SERS) nanotags (Raman reporter-conjugated plasmonic nanoparticles) significantly affects the accuracy and reproducibility of SERS measurements, particularly in biological systems. Limited understanding of SERS nanotag stability may partly hamper the translation of SERS nanotags from the laboratory to their use in the clinic. In this contribution, we utilized differential centrifugal sedimentation (DCS), a reliable and straightforward technique to comprehensively analyze the colloidal stability of SERS nanotags in biological systems. Compared with other particle characterization techniques, DCS has been shown to have a unique advantage for high-resolution and high-throughput polydisperse particle characterization. DCS data revealed that the universal aggregation prevention practice of coating SERS nanotags with silica or bovine serum albumin layers did not sufficiently stabilize them in common measurement environments (e.g., 1× PBS). Combined DCS and SERS measurements established a strong correlation between the degrees of nanotag aggregation and signal intensities, further reinforcing the necessity of characterizing SERS nanotag stability for every condition in which they are used. We also found that increasing the protein thickness by the inclusion of extra protein components in the detection environments and antibody functionalization can improve the stability of SERS nanotags. We believe that this study can provide guidelines on appropriate measurement techniques and particle design considerations to assess and improve SERS nanotag stability in complex biological systems.
关键词： surface-enhanced Raman scattering (SERS),plasmonic nanoparticles,differential centrifugal sedimentation (DCS),SERS nanotags,colloidal stability
更新于2025-09-10 09:29:36
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Effects of fulvic acids and electrolytes on colloidal stability and photocatalysis of nano-TiO2 for atrazine removal
摘要： The colloidal stability and photocatalysis of nano-TiO2 particles were investigated in the presence of fulvic acids (FA) and electrolytes (NaNO3, Na2SO4, Na3PO4) at different pH. Results showed that increasing FA concentration, the absolute value of zeta potential of nano-TiO2 increased and particle size decreased at all pH which promoted the colloidal stability of nano-TiO2. Particle size of nano-TiO2 was larger with the coexistence of FA and electrolytes than with FA only as the concentration of electrolytes was greater than or equal to 0.01 mol/L. The largest particle size occurred in the presence of Na3PO4, followed by Na2SO4 and NaNO3. Particle size of nano-TiO2 decreased with higher pH and stability further increased in the presence of FA and/or electrolytes. Nano-TiO2 stabilization was enhanced by increasing FA concentration when the solution pH was 7.0. However, the removal efficiency of atrazine by nano-TiO2 decreased with the increase in FA concentration. Adding electrolytes (0.01 mol/L), atrazine removal by nano-TiO2 further decreased, albeit slightly. The inhibitory effect of electrolytes on nano-TiO2 removal of atrazine was highest for Na3PO4, followed by Na2SO4, and NaNO3, which were consistent with the results of colloidal stability of nano-TiO2. These findings help to better understand the mechanisms and correlation between colloidal stability and photocatalysis of nano-TiO2 in the presence of FA and electrolytes.
关键词： Atrazine,Fulvic acids,Photocatalysis,Colloidal stability,Electrolytes,Nano-TiO2
更新于2025-09-09 09:28:46