Early detection of cancer has multitude of advantages like early diagnosis, reduced risk, ease in the treatment and follow up of recurrence. New and developed techniques are always under research to control the spreading malignancy. Graphene is an emerging star in biomedical field as it exhibits exceptional thermal, electrical and optical properties. Here, we review application of graphene-based materials in developing biosensing devices for the detection of different cancer biomarkers at concentrations down to sub-toxic levels. Different analytical methodologies chosen for sensing have been undertaken and their performance and background have been discussed. The trend of use of these methodologies can also be perceived from the graphical data presented.
Hollow mesoporous silica nanoparticles (HMSNs) have become an attractive drug carrier because of their unique characteristics including stable physicochemical properties, large specific surface area and facile functionalization, especially made into intelligent drug delivery systems (DDSs) for cancer therapy. HMSNs are employed to transport traditional anti-tumor drugs, which can solve the problems of drugs with instability, poor solubility and lack of recognition, etc., while significantly improving the anti-tumor effect. And an unexpected good result will be obtained by combining functional molecules and metal species with HMSNs for cancer diagnosis and treatment. Actually, HMSNs-based DDSs have developed relatively mature in recent years. This review briefly describes how to successfully prepare an ordinary HMSNs-based DDS, as well as its degradation, different stimuli-responses, targets and combination therapy. These versatile intelligent nanoparticles show great potential in clinical aspects.
Magnetic nanoparticles (MNPs) have widely been synthesized through chemical processes for biomedical applications over the past few decades. Recently, a new class of MNPs, known as bacterial magnetosomes, has been isolated from magnetotactic bacteria, a natural source. These magnetosomes are magnetite or greigite nanocrystals which are biomineralized in the bacterial cell and provide magnet-like properties to it. Contrary to MNPs, bacterial magnetosomes are biocompatible, lower in toxicity, and can be easily cleared from the body due to the presence of a phospholipid bilayer around them. They also do not demonstrate aggregation, which makes them highly advantageous. In this review, we have provided an in-depth comparative account of bacterial magnetosomes and chemically synthesized MNPs in terms of their synthesis, properties, and biomedical applications. In addition, we have also provided a contrast on how magnetosomes might have the potential to successfully substitute synthetic MNPs in therapeutic and imaging applications.
In this work, zwitterionic polymer (polyzwitterion) coated nanodiamonds (ND) with tumorous pH responsiveness were prepared for efficient application of commercial NDs in tumor cells imaging. Poly(carboxybetaine methacrylate) was firstly grafted on the pristine NDs (PCBMA-@-NDs) by surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization. To achieve pH responsiveness and activated interaction with tumor cells, PCBMA-@-NDs were subsequently modified with benzene sulfonamide (PCBSA-@-NDs) via one step carbodiimide chemistry. The surface polymer functionalization was characterized by FTIR, 1H NMR and TGA, and PCBMA-@-NDs and PCBSA-@-NDs showed great dispersibility, enhanced fluorescence intensity and excellent antifouling property in contrast to pristine NDs. Moreover, PCBSA-@-NDs was able to switch zwitterionic surface (at pH 7.4) reversibly into positive charge (at pH 6.5) via protonated or deprotonated acylsulfonamide. As expected, PCBSA-@-NDs demonstrated higher cell affinity and better imaging performance than those of zwitterionic NDs at tumor slight acid environment, proven by fluorescence microscopy and flow cytometry. Overall, we provide a feasible and valuable strategy to construct smart NDs, thus encouraging the application of cost-effective fluorescence nanomaterials in biomedical fields.
In this study, a micro-patterned hydroxyapatite/silk fibroin (HA-SF) coating was firstly fabricated on the surface of Mg–Zn–Y–Nd–Zr alloy by template-assisted electrospraying technique coupling with spin coating technique. Two types of micro-patterns were achieved with high contour accuracy, namely HA-SF(line-pattern) and HA-SF(dot-pattern). The microstructure, composition, surface wettability and corrosion behaviors of the coatings were investigated by SEM, EDS, FTIR, XRD, water contact angle and potentiodynamic polarization test. The results revealed the hydrophilic nature of coatings and two orders of magnitude reduction of corrosion density (icorr) as compared with that of the substrate. All the micro-patterned surfaces promoted the attachment of MC3T3-E1 cells with visible filopodia after 1 d incubation. In addition, coatings with line pattern exhibited the superior guidance to cell migration as compared to dot pattern, and the preference of cell attachment in the convex zone was observed. In summary, the obtained micro-patterned HA-SF coatings possessed the remarkably improvement of anticorrosion ability and good efficacy in guidance of cell attachment and alignment, which can serve as a promising strategy for cellular response modulation at the interface of magnesium-based implants and bone.
A Mg–Al layered double hydroxide (Mg–Al-LDH) coating was firstly synthesized via an in-situ steam coating growth method on the AZ31 Mg alloy, and then was modified with poly(L-lactic acid) (PLLA) via dipping and vacuum freeze-drying. The microstructure and composition of LDH/PLLA hybrid coating were analyzed by XRD, SEM, EDS and FT-IR. The biocorrosion behavior of hybrid coating was evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and hydrogen evolution test in the Hank’s solution. The results showed that LDH/PLLA coatings exhibited a much dense layer compared to the unmodified Mg–Al-LDH coating with unobvious boundary between PLLA and LDH coatings. The corrosion current density of the LDH/PLLA-10 hybrid coating decreased three orders of magnitude in comparison to its substrate. It was proven that the existence of the PLLA coating further prolonged the service life of the Mg–Al-LDH coating. What’s more, the MTT assay and live/dead staining showed that the LDH/PLLA-10 coating had good biocompatibility for Mouse NIH3T3 fibroblasts. The formation mechanism and the anti-corrosion mechanism of hybrid coatings were proposed.
The kinetics of electrode reaction was investigated by cyclic voltammetry, and cyclic voltammograms show that the reversibility of the Fe(bpy)32+/Fe(bpy)33+ electrode reaction is better than that of the Zn/Zn2+ electrode reaction on the graphite disc. However, the Fe(bpy)32+ ion diffusion in electrolyte is subject to greater resistance than that of the Zn2+ ion one. The stability of the Fe(bpy)3Cl2 solution was investigated by UV–vis spectroscopy, and the performance of a mild redox flow battery employing ZnCl2 and Fe(bpy)3Cl2 in the NaCl aqueous solution with various membranes as the separator was also investigated. It was found that the Celgard 3501 membrane cannot effectively prevent Fe(bpy)32+ ions from leaking into anolyte, leading to the rapid failure of the flow battery. Although the Nafion 115 membrane can be polluted by Fe(bpy)32+ ions, it is not invalidated. The Nafion 115 membrane shows good selectivity, which can avoid Fe(bpy)32+ ions from leakage into anolyte. The ZnCl2/Fe(bpy)3Cl2 flow battery with the Nafion 115 membrane exhibits the capacity retention of 80% after 200 cycles.
The unique feather-like arrays composing of ultrathin secondary nanowires are fabricated on nickel foam (NF) through a facile hydrothermal strategy. Thus, the enhancement of electrochemical properties especially the low charge transfer resistance strongly depends on more active sites and porosity of the morphology. Benefiting from the unique structure, the optimized NiCo2O4 electrode delivers a significantly lower charge transfer resistance of 0.32 Ω and a high specific capacitance of 450 F·g−1 at 0.5 A·g−1, as well as a superior cycling stability of 139.6% capacitance retention. The improvement of the electrochemical energy storage property proves the potential of the fabrication of various binary metal oxide electrodes for applications in the electrochemical energy field.
Perovskite oxides based on the alkaline earth metal lanthanum for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline electrolytes are promising catalysts, but their catalytic activity and stability remain unsatisfactory. Here, we synthesized a series of LaFe1−xMnxO3 (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1) perovskite oxides by doping Mn into LaFeO3 (LF). The results show that the doping amount of Mn has a significant effect on the catalytic performance. When x = 0.5, the catalyst LaFe0.5Mn0.5O3 (LFM) exhibits the best performance. The limiting current density in 0.1 mol·L−1 KOH solution is 7 mA·cm−2, much larger than that of the commercial Pt/C catalyst (5.5 mA·cm−2). Meanwhile, the performance of the doped catalyst is also superior to that of commercial Pt/C in terms of the long-term durability. The excellent catalytic performance of LFM may be ascribed to its abundant O2−/O− species and low charge transfer resistance after doping the Mn element.
Developing photocatalysts with wide spectrum absorption and strong nitrogen activation is critical for nitrogen fixation under mild conditions. Herein, one-dimensional natural clay attapulgite (ATP) supported YF3:Sm3+ were successfully synthesized via microwave hydrothermal method, and the composites were employed as the catalyst for photocatalytic nitrogen fixation under visible-light irradiation. Results indicated that the production of ammonia reached as high as 41.2 mg·L−1 within 3 h when the molar ratio of Sm3+ and the mass fraction of YF3:Sm3+ were optimized. The enhanced fixation performance is mainly due to that the modified ATP fibber with abundant active sites and the doped fluoride with defective vacancy facilitate the adsorption and activation of N2. Furthermore, the upconversion property of YF3:Sm3+ increases the harvesting of visible-light energy, meanwhile the Z-scheme heterostructure built between YF3:Sm3+ and modified ATP inhibits the recombination of charge carriers and retains high redox potentials for N2 reduction.
The surface reactivity of metals is fundamentally dependent on the local electronic structure generally tailored by atomic compositions and configurations during the synthesis. Herein, we demonstrate that Cu, which is inert for oxygen reduction reaction (ORR) due to the fully occupied d-orbital, could be activated by applying a visible-light irradiation at ambient temperature. The ORR current is increased to 3.3 times higher in the potential range between −0.1 and 0.4 V under the light of 400 mW·cm−2, and the activity enhancement is proportional to the light intensity. Together with the help of the first-principle calculation, the remarkably enhanced electrocatalytic activity is expected to stem mainly from the decreased metal–adsorbate binding by photoexcitation. This finding provides an additional degree of freedom for controlling and manipulating the surface reactivity of metal catalysts besides materials strategy.
We demonstrate the fabrication of a novel magnetic nanohybrid involving the drug molecule 5-aminolevulinic acid (5-ALA) intercalated Gd–Eu layered rare-earth hydroxide (LRH) coated on magnesium ferrite particles (MgFe2O4). The structure, thermostability, morphology, luminescence properties, cytotoxic effect and magnetism are investigated. The 5-ALA intercalated composite may correspond to a monolayered vertical arrangement, and the thermal stability of organics is enhanced after intercalation. The LRH precursor shows red emission of Eu3+ and the maximum emission peak of the composite is at 451 nm, corresponding to the blue emission. The detection of drug molecules can be realized through the change of luminescence. The magnetic nanohybrid shows strong magnetic sensitivity, which provides an easy and efficient way to separate 5-ALA-MgFe2O4@LGd0.95H:Eu0.05 particles from a sol or a suspension system and to carry drugs to targeted locations under an external magnetic field. The cytotoxic effect of MgFe2O4@LRH is observed with a sulforhodamine B (SRB) colorimetric assay, which has low cytotoxic effects on selected cells. The fabrication of novel bifunctional drug carriers based on LRH with magnetic and fluorescent properties has potential applications in drug detection and drug delivery.