Polydopamine Thin Films Research Articles

A photoelectrochemical sensor based on polydopamine membrane-coated CdS@C core-shell heterostructure for curcumin detection

Curcumin has been widely employed in various fields, but excessive intake may cause tissue necrosis and pose a serious threat to people’s lives and health. Hence, it is crucial to rapidly and precisely detect the content of curcumin. In present research, CdS@C heterostructure materials were successfully prepared through a one-pot solvothermal reaction strategy, utilizing glucose as the carbon source. Simultaneously, polydopamine thin films (ePDA) were successfully deposited on the surface of CdS@C-modified electrodes by the cyclic voltammetry (CV) method. A photoelectrochemical sensor based on the polydopamine membrane-coated CdS@C core–shell heterostructure (ePDA/CdS@C) was designed for curcumin detection. Furthermore, scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible spectrophotometers (UV-vi) techniques were applied to characterize the structure and morphology of the synthesized photoelectric materials. The ePDA coating enhances the stability of the CdS@C material, and the CdS@C core-shell heterostructure accelerates electron transfer. Consequently, the ePDA/CdS@C material generates an outstanding and steady photocurrent response. Under ideal conditions, the novel sensor exhibits a satisfactory linear response to curcumin detection within the concentration range of 0.025–370 μM, with a detection limit as low as 0.0165 μM. Additionally, the ePDA/CdS@C-based photoelectrochemical aptasensor displays remarkable reproducibility, stability, and selectivity. This innovative sensing platform accurately detects curcumin in human serum and urine samples, with an excellent recovery range (99.47 %–103.60 %) and relatively low RSD values (1.49 %–3.56 %). In conclusion, this work offers a novel approach for curcumin detection.

Black phosphorus quantum dots functionalized with photochromic poly(vinylspiropyran)-grafted polydopamine for transient digital-type memristors

Abstract The covalent functionalization of black phosphorus quantum dots (BPQDs) with organic species or polymers will inevitably change or damage their electronic structure and intrinsic structure. To address this problem and explore the application of BPQDs in transient digital-type memristors, a polydopamine (PDA) thin film is first synthesized in situ onto the surface of BPQDs to produce a donor–acceptor-type BPQDs@PDA composite that is directly used to react with 2-bromoisobutyryl bromide to give BPQDs@PDA-Br. By using BPQDs@PDA-Br as an atom transfer radical polymerization agent, a large number of polyvinylspiropyran (PSP) chains are in situ grown from the PDA surface to yield BPQDs@PDA-PSP. Upon ultraviolet (UV)–visible light illumination, the 2 isomers of the spiropyran (ring-closed spiropyran form and ring-opened merocyanine) in the PSP moieties will interconvert into each other rapidly. As expected, the as-fabricated indium tin oxide (ITO)/BPQDs@PDA-PSP/ITO device exhibits typical nonvolatile digital-type memristive performance under visible irradiation, with a small turn-on voltage of −1.52 V, a turn-off voltage of +1.16 V, and an ON/OFF ratio current ratio of 1.02 × 104. Upon UV illumination, the information stored in the device is quickly and completely erased within 6 s. By utilizing a simple memristor-based convolutional neural network, one can easily realize handwritten digit recognition. After 10 epochs of training, numeral recognition accuracy can reach up to 96.21%.

Preparation and Photothermal Antimicrobial Performance of Triple Linkage Hydrogels

Often, bacterial infections delay the rate of healing of traumatic wounds, making it critical to improve antimicrobial efficiency. In this paper, titanium nanotubes (TNT) with good antimicrobial and synergistic photothermal properties were used as the core, and mesoporous polydopamine (MPDA) thin films were constructed on their surface. Gold nanoparticles (AuNPs) with excellent photothermal conversion efficiencies (PCE) were incorporated. Finally, a large number of composite nanoparticles were added to polyvinyl alcohol (PVA) and polyethylene glycol (PEG) with wound-restoring ability, and an injectable antimicrobial hydrogel was successfully prepared by a one-pot synthesis. The antimicrobial effect of TNT@MPDA@Au nanoparticles with different concentrations was assessed by in vitro antimicrobial experiments on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The higher the concentration of nanoparticles under near-infrared light irradiation (NIR), the stronger the antimicrobial effect. The in vitro cytotoxicity of TNT@MPDA and TNT@MPDA@Au nanoparticles on 293T normal cells was tested through CCK-8 assay. The results show that both nanoparticles have favourable biocompatibility. In this paper, a three-component synergistic photothermal antimicrobial nano-antimicrobial platform was constituted by incorporating MPDA, a photothermal agent with excellent biocompatibility and photothermal properties, and AuNPs with good photothermal properties on TNT with excellent photocatalytic properties.

Structural properties of aqueous grown polydopamine thin films determined by neutron reflectometry

In this work, neutron reflectometry (NR) studies of the bio-mimetic polymer, polydopamine (PDA), deposited from differing initial concentrations of precursor material dopamine hydrochloride for a range of polymerization times, is reported. PDA can form a complex and highly versatile polymer film, with many structure studies having been performed previously, but a comprehensive structural determination of PDA by NR is lacking in the literature. It was found that simple box models were incapable of fully explaining the observed data, necessitating the use of a composite model consisting of the weighted average of both the 1 and 2 box models to fully capture the heterogeneous nature of the PDA film structure. Confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM) were performed to capture the surface structure and relative mechanical difference between the separate domains of the PDA. The CLSM results provide evidence that the PDA domains are larger than the coherent scattering length of a neutron used in these measurements, 10μm, supporting the need for a composite model. The AFM measurements show complex structure below the coherence length provide physical justification for the two box model. It was determined that film structure and quality are both heavily impacted by the initial concentration of dopamine hydrochloride and the polymerization time, giving confidence to the highly customizable nature of PDA as an adhesion promoting interface treatment in composite systems, such as plastic bonded explosives (PBX).

Recognition of bovine hemoglobin protein on molecularly imprinted polymer surfaces using nonlinear vibrational spectroscopy

Advancement in molecularly imprinted biomimetics has aided in developing robust artificial recognition-based materials, which can be customized for bio/chemo-sensing of distinct molecules. The present study reports a simple one-step synthesis and analysis of protein-imprinted polymer thin films as a recognition element directly onto a solid support. Dopamine has been explored as a versatile functional monomer for a molecularly imprinted polymer (MIP) matrix to fabricate polydopamine (PDA) thin films with bovine hemoglobin as a template protein molecule. A detailed molecular-level insight into the recognition of the template molecule at each step has been investigated using vibrational sum frequency generation (VSFG) spectroscopy. A suitable PDA-coated thin film is selected based on the extent of polymerized intermediates formed after non-imprinted polymer fabrication at different time durations. An optimally prepared film of MIP is specified by observing the spectral signature of the methyl groups from protein molecules at the air–polymer interface. The template removal from MIP films after the washing procedure and subsequent re-binding of the protein molecules were evaluated by VSFG spectroscopy. The insightful molecular-level findings from SFG spectroscopy demonstrate the fabrication of an imprinted matrix as a label-free chemical sensor.

Improve the Interfacial Properties between Poly(arylene sulfide sulfone) and Carbon Fiber by Double Polymeric Grafted Layers Designed on a Carbon Fiber Surface.

Double polymeric grafted layer is constructed by two steps of chemical reaction, in which two polymers had been used, respectively polydopamine (PDA) film and modified PASS (NH2-PASS) resin containing amine group, as the interphase in carbon fiber reinforced poly(arylene sulfide sulfone) (PASS) composite (CF/PASS) to work on enhancing the interfacial property. All the test results of chemical components and chemical structures on the carbon fiber surface show that the double polymeric grafted layer was constructed successfully with PDA and NH2-PASS chains. And obvious characteristics of thin PDA film and a polymer layer can be clearly seen in the morphology of modified carbon fiber. In addition to this, the obvious interphase and change in the thickness of interphase have been observed in the modulus distribution images of CF/PASS. The final superb performance is achieved by PASS composites with a double polymeric grafted layer, 27.2% and 198.6% superior to the original PASS composite for IFSS and ILSS, respectively. Moreover, the result also indicates that constructing a double polymeric grafted layer on a carbon fiber surface is a promising technique to modify carbon fiber for processing high-performance advanced thermoplastic composites and is more environmental friendly as well as convenient.

Self-Regulating Solar Steam Generators Enable Volatile Organic Compound Removal through In Situ H2O2 Generation.

Interfacial solar steam generation for clean water production suffers from volatile organic compound (VOC) contamination during solar-to-steam conversion. Here, we present a solar steam generator based on the integration of melamine foam (MF), polydopamine (PDA), and Ag/AgCl particles. Together with the high photothermal conversion efficiency (ca. 87.8%, 1 kW/m2) achieved by the PDA thin film, the Ag/AgCl particles can efficiently activate the localized generation of H2O2 and •OH in situ, thus degrading the VOCs during the rapid vapor generation. The generation of H2O2 and •OH in situ also facilitates the creation of a buffer zone containing H2O2 and •OH for the rapid removal of organic pollutants in the surrounding water attracted to the solar vapor generator, demonstrating a self-cleaning steam generator toward various volatile compounds such as phenol, aniline, 2,4-dichlorophenol, and N,N-dimethylformamide in a wide range of concentrations.

Biomimetic design of functional plasmonic surfaces based on polydopamine

Polydopamine is a bioinspired multifunctional material that is emerging in the last years for applications in the biomedical, energy, environmental and catalytic fields. Whereas the conformal coating of solid objects by polydopamine is a well assessed process, the development of polydopamine thin films is less explored and their potential advantages have still to be fully unveiled. Herein, we describe a green and straightforward fabrication of composite membranes based on polydopamine thin films self-assembled at the air/water interface, and two different biopolymers, bacterial cellulose and silk fibroin. Furthermore, the abundant phenolic hydroxyl groups enable the in situ Au nanoparticle decoration on the polydopamine side, providing the membrane surface with plasmonic features. The surface patterning of polydopamine layers using self-assembled templating structures is also demonstrated, opening up new perspectives for biocompatible functional membranes with tunable optical and spectroscopic properties. Lastly, we demonstrate that the obtained functional surfaces are promising tools for the fabrication of SERS substrates. By bridging dopamine chemistry with natural biopolymers and 2D photonic crystals, the results obtained within this paper establish an excellent platform for designing 2D nanoarchitectures with multiple functions.

Physicochemical and Electrochemical Characterization of Electropolymerized Polydopamine Films: Influence of the Deposition Process.

Polydopamine (PDA) is a synthetic eumelanin polymer which is, to date, mostly obtained by dip coating processes. In this contribution, we evaluate the physical and electrochemical properties of electrochemically deposited PDA films obtained by cyclic voltammetry or pulsed deposition. The obtained PDA thin films are investigated with respect to their electrochemical properties, i.e., electron transfer (ET) kinetics and charge transfer resistance using scanning electrochemical microscopy and electrochemical impedance spectroscopy, and their nanomechanical properties, i.e., Young’s modulus and adhesion forces at varying experimental conditions, such as applied potential or pH value of the medium using atomic force microscopy. In particular, the ET behavior at different pH values has not to date been investigated in detail for electrodeposited PDA thin films, which is of particular interest for a multitude of applications. Adhesion forces strongly depend on applied potential and surrounding pH value. Moreover, force spectroscopic measurements reveal a significantly higher percentage of polymeric character compared to films obtained by dip coating. Additionally, distinct differences between the two depositions methods are observed, which indicate that the pulse deposition process leads to denser, more cross-linked films.

Polydopamine film coating on polyurethane foams as efficient “sunscreen”. Application to photocatalysis under UV irradiation

Polyurethanes are used in a large variety of commercial and technical applications, due to their high tensile strength, chemical resistance, good process ability and good mechanical properties. In particular, polyurethane open cell foams appear as ideal candidates to design original photoreactors. However, due to their high sensitivity to UV light, polyurethane foams can be not used directly as structured photocatalytic supports. In this work, we show that a simple thin polydopamine film coating on the foam surface plays a “sunscreen” role, protecting the polyurethane foam from UV A or UV C degradation and inhibiting volatile organic compounds’ emanation. Furthermore, when loaded with TiO 2 particles, these functionalized foams allowed developing an efficient photocatalytic system for the degradation of formic acid in water and the mineralization of acetaldehyde, n -heptane, toluene and acetone in air. • Polydopamine film bio-inspired as efficient “sunscreen” for polyurethane foam. • New photo-reactor based on open cell foam - TiO 2 . • Versatile system for both mineralization of formic acid in water and VOCs in air.

Polydopamine Ultrathin Film Growth on Mica via In-Situ Polymerization of Dopamine with Applications for Silver-Based Antimicrobial Coatings

The development of polydopamine (PDA) coatings with a nanometer-scale thickness on surfaces is highly desirable for exploiting the novel features arising from the specific structure on the molecular level. Exploring the mechanisms of thin-film growth is helpful for attaining desirable control over the useful properties of materials. We present a systematic study demonstrating the growth of a PDA thin film on the surface of mica in consecutive short deposition time intervals. Film growth at each deposition time was monitored through instrumental techniques such as atomic force microscopy (AFM), water contact angle (WCA) analysis, and X-ray photoelectron spectroscopy (XPS). Film growth was initiated by adsorption of the PDA molecules on mica, with subsequent island-like aggregation, and finally, a complete molecular level PDA film was formed on the surface due to further molecular adsorption. A duration of 60−300 s was sufficient for complete formation of the PDA layer within the thickness range of 0.5−1.1 nm. An outstanding feature of PDA ultrathin films is their ability to act as a molecular adhesive, providing a foundation for constructing functional surfaces. We also explored antimicrobial applications by incorporating Ag nanoparticles into a PDA film. The Ag NPs/PDA film was formed on a surgical blade and then characterized and confirmed by SEM-EDS and XPS. The modified film inhibited bacterial growth by up to 42% on the blade after cutting through a pork meat sample.

Plasmonic active film integrating gold/silver nanostructures for H2O2 readout

A nanostructured Ag/Au adhesive film for H2O2 reagentless determination is here proposed. The film has been realised onto ELISA polystyrene microplates. Microwells surface has been initially modified with a gold nanoparticles (AuNPs)/polydopamine thin-film. The pristine AuNPs-decorated film was later functionalized with catechin (Au-CT) allowing a uniform formation of a plasmonic active nanostructured silver network in presence of Ag+. Changes in localized surface plasmon resonance (LSPR) of the silver network upon addition of H2O2 has been used as analytical signal, taking advantage of the etching phenomenon. The Ag/Au nanocomposite-film is characterized by a well-defined (LSPRmax = 405 ± 5 nm), reproducible (intraplate RSD ≤ 9.8%, n = 96; inter-plate RSD ≤ 11.4%, n = 480) and stable LSPR signal. The film's analytical features have been tested for H2O2 and glucose (bio)sensing. Satisfactory analytical performances were obtained both for H2O2 (linear range 1–200 μM, R2 = 0.9992, RSD ≤ 6.3%, LOD = 0.2 μM) and glucose (linear range 2–250 μM, R2 = 0.9998, RSD ≤ 8.9%, LOD = 0.4 μM). As proof of applicability, the determination of the two analytes in soft drinks has been carried out achieving good and reproducible recoveries (84–111%; RSD ≤ 9%). The developed nanostructured film overcomes analytical drawbacks associated with the use of colloidal dispersions in plasmonic assays carried out in solution; the low cost, robustness, ease of use and possibility of coupling enzymatic reactions appears very promising for (bio)sensors based on the detection of H2O2.

Metallic Nanoparticle-Decorated Polydopamine Thin Films and Their Cell Proliferation Characteristics

Plasmonic metal nanoparticle (NP)-decorated thin films of biobased and biocompatible polymers provide significant opportunities in various biomedical applications. Inspired from the adhesive proteins of the marine mussels, polydopamine (PDA) serves as a versatile, biocompatible, and simple thin-film material and enhances cell growth and proliferation. Herein, we report the fabrication of the gold NPs (AuNPs) or silver NPs (AgNPs)-deposited thin films of PDA and their employment in cell growth and proliferation. PDA thin film with its numerous functional groups enabled well-controlled adsorption of NPs. The number density of NPs was manipulated simply by tuning the deposition time. Cell viability test for human lung cancer (A549) and human colon cancer (CaCO2) cell lines indicated that a thin layer of PDA film remarkably enhanced the cell growth and proliferation. The lower number density of NPs for the 24 h of the culture time resulted in a higher proliferation rate. However, the increase in both the number density of NPs and culture time led to a decrease in cell growth.

The Application of Reactive Polydopamine Thin Films for the Functionalization of Tissue Culture Plastic with Alkaline Phosphatase

Aseptic loosening continues to be the major cause of total joint replacement (TJR) failure...

Mimicking Noble Metals Using Hydrogen-Bonded Conducting Polymers for Electrocatalysis

The most active and efficient catalysts for the electrochemical hydrogen evolution reaction rely on noble metals, a fact that increases the cost of producing hydrogen and thereby limits the widespread adoption of this fuel. Here we present metal-free polydopamine and polyguanine as selective organic hydrogen electrocatalysts1–3. The conducting functional polymers incorporate selective hydrogen-affine hydrogen bonds that possess a similar hydrogen binding energies and work function as e.g. platinum. We report the synthesis of hydrogen-selective electrocatalytic polyguanine and polydopamine and demonstrate the enhancement of the rate-determining step in the proton reduction. We further present mechanistic spectral IR-operando studies on the catalytic hydrogen bonded motifs as well as the continuous electrolysis to molecular hydrogen using polyguanine and polydopamine electrodes for several 100 hours without notable degradation.(1) Coskun, H.; Aljabour, A.; Schöfberger, W.; Hinterreiter, A.; Stifter, D.; Sariciftci, N. S.; Stadler, P. Cofunction of Protons as Dopant and Reactant Activate the Electrocatalytic Hydrogen Evolution in Emeraldine‐Polyguanine. Adv. Mater. Interfaces 2019, 1901364 DOI: 10.1002/admi.201901364.(2) Coskun, H.; Aljabour, A.; Uiberlacker, L.; Strobel, M.; Hild, S.; Cobet, C.; Farka, D.; Stadler, P.; Sariciftci, N. S. Chemical Vapor Deposition - Based Synthesis of Conductive Polydopamine Thin-Films. Thin Solid Films 2018, 645 (August 2017), 320–325 DOI: 10.1016/j.tsf.2017.10.063.(3) Coskun, H.; Aljabour, A.; Luna, P. De; Sun, H.; Nishiumi, N.; Yoshida, T.; Koller, G.; Ramsey, M. G.; Greunz, T.; Stifter, D.; Hassel, A. W.; Sariciftci, N. S.; Sargent, E. H.; Stadler, P. Hydrogen-Bonded Polymers Mimic Noble Metal Electrocatalysts. Adv. Mater., submitted.

Bio-Inspired Polydopamine Mimic Noble Metal Electrocatalysts in Hydrogen Evolution Reaction

The main electrocatalysts for the electrochemical hydrogen evolution reaction (HER) rely on platinum due to high efficiencies, low binding energy for hydrogen and high electroactive-site density, however the cost of platinum is a crucial limitation for the production of hydrogen by this rare metal.[1] Here, we establish a metal-free and bio-organic electrocatalyst platform that resembles the platinum surface by incorporating hydrogen-affine hydrogen bonds. We introduce keto-amine functional motifs, which act as selective reaction centres.[2, 3] The keto-amine-functionalized biopolymer shown in this work evolve hydrogen at the lowest overpotential in a non-metallic system. With excellent electrochemical stability and chemical robustness, we are able to present a scale-up continuous-flow electrolysis and produce 1 L net molecular hydrogen within less than 9 hours using 2.3 mg of biopolymer electrocatalyst.[1] Y. Zheng, Y. Jiao, Y. Zhu, L.H. Li, Y. Han, Y. Chen, A. Du, M. Jaroniec, S.Z. Qiao, Hydrogen evolution by a metal-free electrocatalyst, Nature Communications, 5 (2014) 3783.[2] H. Coskun, A. Aljabour, P. De Luna, D. Farka, T. Greunz, D. Stifter, M. Kus, X.L. Zheng, M. Liu, A.W. Hassel, W. Schofberger, E.H. Sargent, N.S. Sariciftci, P. Stadler, Biofunctionalized conductive polymers enable efficient CO2 electroreduction, Science Advances, 3 (2017).[3] H. Coskun, A. Aljabour, L. Uiberlacker, M. Strobel, S. Hild, C. Cobet, D. Farka, P. Stadler, N.S. Sariciftci, Chemical vapor deposition - based synthesis of conductive polydopamine thin-films, Thin Solid Films, 645 (2018) 320-325.

Polydopamine-Lysophosphatidate-Functionalised Titanium: A Novel Hybrid Surface Finish for Bone Regenerative Applications.

Aseptic loosening of total joint replacements (TJRs) continues to be the main cause of implant failures. The socioeconomic impact of surgical revisions is hugely significant; in the United Kingdom alone, it is estimated that £135m is spent annually on revision arthroplasties. Enhancing the longevity of titanium implants will help reduce the incidence and overall cost of failed devices. In realising the development of a superior titanium (Ti) technology, we took inspiration from the growing interest in reactive polydopamine thin films for biomaterial surface functionalisations. Adopting a “one-pot” approach, we exposed medical-grade titanium to a mildly alkaline solution of dopamine hydrochloride (DHC) supplemented with (3S)1-fluoro-3-hydroxy-4-(oleoyloxy)butyl-1-phosphonate (FHBP), a phosphatase-resistant analogue of lysophosphatidic acid (LPA). Importantly, LPA and selected LPA analogues like FHBP synergistically cooperate with calcitriol to promote human osteoblast formation and maturation. Herein, we provide evidence that simply immersing Ti in aqueous solutions of DHC-FHBP afforded a surface that was superior to FHBP-Ti at enhancing osteoblast maturation. The facile step we have taken to modify Ti and the biological performance of the final surface finish are appealing properties that may attract the attention of implant manufacturers in the future.

Using A Spin-Coater to Capture Adhesive Species during Polydopamine Thin-Film Fabrication.

Spin-coating was evaluated as a technique to study events that occur during polydopamine (PDA) thin-film formation. The reaction variants studied included type of oxidant, dopamine (DA) concentration, pH, adhesion time prior to spin, substrate chemistry, and notably, DA solution aging time. A strong oxidant, sodium periodate (SP), and a weak oxidant, atmospheric oxygen were chosen. It was found that reactions in solution were much faster and produced much thicker PDA films with SP than with oxygen. PDA thickness correlated positively with DA concentration, SP solution pH, and adhesion time. DA oxidation and aggregation is a dynamic process, which is reflected in the DA aging-time parameter. PDA film thickness reached a maximum value as DA solution aged. Color photography, UV-vis spectroscopy, and dynamic light scattering indicated that the optimal DA aging time for PDA adhesion is the result of the evolution of PDA particle size and chemistry over time. The capture of the optimal aging-time window was identified as the critical parameter for preparing PDA films with continuity and appreciable thickness. When these conditions were applied in a modified dip-coating method, comparable PDA films were fabricated as those obtained from spin-coating. Native silicon wafers (SiO2) as well as wafers that were modified with polydimethylsiloxane (PDMS) and amine-containing polydimethylsiloxane (PADMS) were chosen to represent a wide range of substrates with different substrate-PDA interactions. The main effect of substrate structural difference was on PDA film morphology. "Island" morphologies were obtained on PDMS where only hydrophobic interactions are responsible for PDA adhesion, while "speck" morphologies were observed on SiO2 and PADMS. The stabilities of the fabricated PDA films were tested in 0.1 M HCl and DMSO. The SP-derived PDA films exhibited very little mass loss compared to those fabricated using either the conventional dip-coating method or oxygen as an oxidant. Choosing a strong oxidant, understanding the DA reaction dynamics, and taking advantage of the optimal DA aging time are important in the fabrication of stable PDA films on a variety of substrates.

Electrochemical deposition of bio-inspired laccase-polydopamine films for phenolic sensors

Hereby, a precisely controlled one-step electrode modification is presented where the enzyme laccase is immobilized during the potentiostatic deposition of a thin polydopamine film (ePDA) on carbon surfaces. The morphology, wettability, optical and electrochemical properties of the modified electrodes were accessed by atomic force microscopy, water contact angle goniometry, ellipsometry and cyclic voltammetry. The results indicate that laccase is robustly immobilized and evenly distributed in the ePDA matrix, not significantly affecting the redox behavior of the polymer. The catalytic activity of the laccase-polymer modified electrodes is confirmed by chronoamperometry for 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) detection, a well-known substrate of laccase. The proposed fast and efficient one-pot procedure is implemented on cheap disposable graphite electrodes, targeting the detection of phenolic compounds: caffeic acid, rosmarinic acid and gallic acid. The catalytic performance of the modified electrodes was evaluated in terms of reproducibility, sensitivity, limits of detection (LOD) and linear range. For gallic acid a calibration curve with a sensitivity of 19.3 mA M−1 cm−2, 1–150 μM linear range and a LOD of 0.29 μM is obtained, allowing the estimation of the low molecular weight phenols content in an extract of chestnut shell industrial waste.

Polydopamine-based surface modification of paclitaxel nanoparticles for osteosarcoma targeted therapy

In order to achieve the purpose of targeting treatment of osteosarcoma, we developed novel paclitaxel (PTX) nanoparticles (Nps) coated with polydopamine (PDA) and grafted by alendronate (ALN) as ligand. Dopamine can be easily polymerized on various surfaces to form a thin PDA film in alkaline environment, which provided a versatile platform to perform secondary reactions for compounds without functional groups. The targeting Nps had a mean particle size of 290.6 ± 2.2 nm and a zeta potential of −13.4 ± 2.7. It was stable in phosphate buffer saline (PBS, pH 7.4), 5% glucose, plasma and displayed sustained drug release behavior. In vitro assay demonstrated the targeting Nps had stronger cytotoxicity against K7M2 wt osteosarcoma cells than the non-targeting Nps. Furthermore, in vivo distribution study indicated they could accumulate much more in tumor than non-targeting Nps. This is consistent with the in vivo antitumor study, targeting Nps achieved a better therapeutic effect than Taxol (8 mg kg−1, i.v.) (71.85% versus 66.53%) and prominently decreased the side effects of PTX. In general, the PTX-PDA-ALN-Nps may offer a feasible and effective strategy for osteosarcoma targeted therapy.