An intracellular delivery system for CRISPR/Cas9 is crucial for its application as a therapeutic genome editing technology in a broad range of diseases. Current vehicles carrying CRISPR/Cas9 limit in ...vivo delivery because of low tolerance and immunogenicity; thus, the in vivo delivery of genome editing remains challenging. Here, we report that cancer-derived exosomes function as natural carriers that can efficiently deliver CRISPR/Cas9 plasmids to cancer. Compared to epithelial cell-derived exosomes, cancer-derived exosomes provide potential vehicles for effective in vivo delivery via selective accumulation in ovarian cancer tumors of SKOV3 xenograft mice, most likely because of their cell tropism. CRISPR/Cas9-loaded exosomes can suppress expression of poly (ADP-ribose) polymerase-1 (PARP-1), resulting in the induction of apoptosis in ovarian cancer. Furthermore, the inhibition of PARP-1 by CRISPR/Cas9-mediated genome editing enhances the chemosensitivity to cisplatin, showing synergistic cytotoxicity. Based on these results, tumor-derived exosomes may be very promising for cancer therapeutics in the future.
Graphical abstract Display omitted
Ni‐rich layered oxides and Li‐rich layered oxides are topics of much research interest as cathodes for Li‐ion batteries due to their low cost and higher discharge capacities compared to those of ...LiCoO2 and LiMn2O4. However, Ni‐rich layered oxides have several pitfalls, including difficulty in synthesizing a well‐ordered material with all Ni3+ ions, poor cyclability, moisture sensitivity, a thermal runaway reaction, and formation of a harmful surface layer caused by side reactions with the electrolyte. Recent efforts towards Ni‐rich layered oxides have centered on optimizing the composition and processing conditions to obtain controlled bulk and surface compositions to overcome the capacity fade. Li‐rich layered oxides also have negative aspects, including oxygen loss from the lattice during first charge, a large first cycle irreversible capacity loss, poor rate capability, side reactions with the electrolyte, low tap density, and voltage decay during extended cycling. Recent work on Li‐rich layered oxides has focused on understanding the surface and bulk structures and eliminating the undesirable properties. Followed by a brief introduction, an account of recent developments on the understanding and performance gains of Ni‐rich and Li‐rich layered oxide cathodes is provided, along with future research directions.
Ni‐rich layered oxides and Li‐rich layered oxides are part of a new generation of high‐capacity Li‐ion battery cathodes currently under development. The current state of research on these two families of materials, some of the obstacles to further implementation, and some future areas of exploration are outlined.
Micrometer‐size LiFePO4 spheres with homogeneous double carbon coating layers have been prepared as potential electrode materials for battery applications. The double carbon‐coated LiFePO4 electrodes ...in a lithium‐ion cell exhibited discharge capacities of the order of 160 mAh g−1 and 115 mAh g−1 at 25 °C under 0.1 C‐rate and 10 C‐rate, respectively.
A cathode material of an electrically conducting carbon‐LiMnPO4 nanocomposite is synthesized by ultrasonic spray pyrolysis followed by ball milling. The effect of the carbon content on the ...physicochemical and electrochemical properties of this material is extensively studied. A LiMnPO4 electrode with 30 wt% acetylene black (AB) carbon exhibits an excellent rate capability and good cycle life in cell tests at 55 and 25 °C. This electrode delivers a discharge capacity of 158 mAh g−1 at 1/20 C, 126 mAh g−1 at 1 C, and 107 mAh g−1 at 2 C rate, which are the highest capacities reported so far for this type of electrode. Transmission electron microscopy and Mn dissolution results confirm that the carbon particles surrounding the LiMnPO4 protect the electrode from HF attack, and thus lead to a reduction of the Mn dissolution that usually occurs with this electrode. The improved electrochemical properties of the C‐LiMnPO4 electrode are also verified by electrochemical impedance spectroscopy.
The addition of acetylene black (AB) carbon to a nanostructured C‐LiMnPO4 cathode material results in an extraordinary electrode material for a lithium cell with very high reversible capacity and an excellent cycle life. The composite can easily be made by ultrasonic spray pyrolysis followed by ball milling. Microscopic studies confirm that the carbon particles protect the cathode materials from dissolution.
As nickel-rich layered oxide cathodes start to attract worldwide interest for the next-generation lithium-ion batteries, their long-term cyclability in full cells remains a challenge for electric ...vehicles. Here we report a long-life Ni-rich layered oxide cathode (LiNi0.7Co0.15Mn0.15O2) with a uniform surface coating of the cathode particles with Li2ZrO3. A pouch-type full cell fabricated with the Li2ZrO3-coated cathode and a graphite anode displays 73.3% capacity retention after 1500 cycles at a C/3 rate. The Li2ZrO3 coating has been optimized by a systematic study with different synthesis approaches, annealing temperatures, and coating amounts. The complex relationship among the coating conditions, uniformity, and morphology of the coating layer and their impacts on the electrochemical properties are discussed in detail.
Delivery of high capacity with good retention is a challenge in developing cathodes for rechargeable sodium-ion batteries. Here we present a radially aligned hierarchical columnar structure in ...spherical particles with varied chemical composition from the inner end (NaNi0.75Co0.02Mn0.23O2) to the outer end (NaNi0.58Co0.06Mn0.36O2) of the structure. With this cathode material, we show that an electrochemical reaction based on Ni(2+/3+/4+) is readily available to deliver a discharge capacity of 157 mAh (g-oxide)(-1) (15 mA g(-1)), a capacity retention of 80% (125 mAh g(-1)) during 300 cycles in combination with a hard carbon anode, and a rate capability of 132.6 mAh g(-1) (1,500 mA g(-1), 10 C-rate). The cathode also exhibits good temperature performance even at -20°C. These results originate from rather unique chemistry of the cathode material, which enables the Ni redox reaction and minimizes the surface area contacting corrosive electrolyte.
To investigate the effect of electrical conductivity on the energy‐storage characteristics of anode materials in sodium‐ion batteries, covalent organic nanosheets (CONs) are hybridized with highly ...conductive graphene nanosheets (GNs) via two different optimized synthesis routes, that is, reflux and solvothermal methods. The reflux‐synthesized hybrid shows a well‐overlapped 2D structure, whereas the solvothermally prepared hybrid forms a segregated phase in which the contact area between the CONs and GNs is reduced. These two hybrids synthesized by facile methods are fully characterized, and the results reveal that their energy‐storage properties can be significantly improved by enhancing the electrical conductivity via the formation of a well‐overlapped structure between CONs and GNs. The discharge capacity and rate capability of the reflux‐synthesized hybrid was considerably larger than that of the bare CONs, highlighting that the improvement in the charge‐carrier transport properties can improve the accessibility of Na ions to the surface of the hybrids. This synthetic methodology can be extended to the fabrication of high‐performance anodes for Na‐ion batteries.
Not size by method matters: Rational design for the hybridization between covalent organic nanosheets and graphene nanosheets can lead to an effective control of electrical conductivity of anodes in sodium ion batteries. Compared to a reflux‐prepared hybrid (CON‐G‐16) with a segregated phase, solvothermally‐synthesized hybrid (CON‐G‐10) consisting of well‐overlapped nanosheets shows much higher energy density and rate capability, highlighting the importance of conductivity.
Dissolution of Ir oxides in Ir‐based catalysts, which is closely linked to the catalyst activity and stability toward the oxygen evolution reaction (OER) in acidic media, is a critical unresolved ...problem in the commercialization of water electrolysis. Doping foreign elements into the Ir oxides can accomplish an optimal combination of Ir oxidation states that is conducive to the leaching‐resistance of active catalytic sites. Here, it is reported that Pt doping into IrOx‐based nanoframe is beneficial in both terms of activity and stability. The Pt‐doped IrOx‐based nanoframe achieves the mass activity of 0.644 A mg−1Ir+Pt at 1.53 VRHE, which is 15‐fold higher than that of the commercial IrO2. During the accelerated durability test, the IrIV‐to‐IrIII ratio of 5 is maintained in the presence of Pt dopant to effectively mitigate the degradation of Ir catalyst, leading to the superb catalyst durability in acidic media.
The proper degree of Pt doping in electrochemically activated IrOx based catalysts is the key to forming defective and amorphous IrOx surfaces, and optimizing the active IrIII and stable IrIV, which is beneficial for high activity and stability toward the oxygen evolution reaction in acidic media.
The Ni‐rich layered oxides with a Ni content of >0.5 are drawing much attention recently to increase the energy density of lithium‐ion batteries. However, the Ni‐rich layered oxides suffer from ...aggressive reaction of the cathode surface with the organic electrolyte at the higher operating voltages, resulting in consequent impedance rise and capacity fade. To overcome this difficulty, we present here a heterostructure composed of a Ni‐rich LiNi0.7Co0.15Mn0.15O2 core and a Li‐rich Li1.2−
x
Ni0.2Mn0.6O2 shell, incorporating the advantageous features of the structural stability of the core and chemical stability of the shell. With a unique chemical treatment for the activation of the Li2MnO3 phase of the shell, a high capacity is realized with the Li‐rich shell material. Aberration‐corrected scanning transmission electron microscopy (STEM) provides direct evidence for the formation of surface Li‐rich shell layer. As a result, the heterostructure exhibits a high capacity retention of 98% and a discharge‐voltage retention of 97% during 100 cycles with a discharge capacity of 190 mA h g−1 (at 2.0–4.5 V under C/3 rate, 1C = 200 mA g−1).
To develop high‐performance cathodes, a heterostructure composed of Ni‐rich layered oxide core and a lithium‐rich Li1.2−xNi0.2Mn0.6O2 shell is explored. The heterostructure overcomes the critical drawbacks of both the surface electrochemical instability with electrolyte of the core material as well as the voltage decline problem of the shell layer.
An attempt was made to control the surface charge of colloidal silica nanoparticles with 20 nm and 100 nm diameters. Untreated silica nanoparticles were determined to be highly negatively charged and ...have stable hydrodynamic sizes in a wide pH range. To change the surface to a positively charged form, various coating agents, such as amine containing molecules, multivalent metal cation, or amino acids, were used to treat the colloidal silica nanoparticles. Molecules with chelating amine sites were determined to have high affinity with the silica surface to make agglomerations or gel-like networks. Amino acid coatings resulted in relatively stable silica colloids with a modified surface charge. Three amino acid moiety coatings (L-serine, L-histidine, and L-arginine) exhibited surface charge modifying efficacy of L-histidine > L-arginine > L-serine and hydrodynamic size preservation efficacy of L-serine > L-arginine > L-histidine. The time dependent change in L-arginine coated colloidal silica was investigated by measuring the pattern of the backscattered light in a Turbiscan™. The results indicated that both the 20 nm and 100 nm L-arginine coated silica samples were fairly stable in terms of colloidal homogeneity, showing only slight coalescence and sedimentation.
PDF
