As new 2D layered nanomaterials, Bi
O
Se nanoplates have unique semiconducting properties that can benefit biomedical applications. Herein, a facile top-down approach for the synthesis of Bi
O
Se ...quantum dots (QDs) in a solution is described. The Bi
O
Se QDs with a size of 3.8 nm and thickness of 1.9 nm exhibit a high photothermal conversion coefficient of 35.7% and good photothermal stability. In vitro and in vivo assessments demonstrate that the Bi
O
Se QDs possess excellent photoacoustic (PA) performance and photothermal therapy (PTT) efficiency. After systemic administration, the Bi
O
Se QDs accumulate passively in tumors enabling efficient PA imaging of the entire tumors to facilitate imaging-guided PTT without obvious toxicity. Furthermore, the Bi
O
Se QDs which exhibit degradability in aqueous media not only have sufficient stability during in vivo circulation to perform the designed therapeutic functions, but also can be discharged harmlessly from the body afterward. The results reveal the great potential of Bi
O
Se QDs as a biodegradable multifunctional agent in medical applications.
This study aimed to investigate the variation of structure and nanomechanical properties of human articular cartilage (AC) at different stages of osteoarthritis (OA). The nanoscale morphology, ...chemical composition, variation of chemical structure, surface adhesion force and elastic modulus were examined. The thickening of collagen fibrils and a decreasing trend of their D-periodic banding patterns were observed along with the progression of OA. The calcium and phosphate concentration in AC showed an increasing trend from Grade 0 to Grade 3. These findings suggest that collagen fibrils have reduced intermolecular interactions, greater molecular disorder and decreased amount and stability of crosslinks in collagen, which may affect the stability of collagen fibrils. The surface adhesion force showed a decreasing trend while the elastic modulus of individual collagen fibrils showed an increasing trend with the advancement of OA, which was confirmed to have a direct functional consequence in the nanostructure of collagen fibrils. This study is helpful for understanding OA pathogenesis and providing an efficient strategy for pre-symptomatic diagnostics of OA.
•PLLA nanofibers produced by TIPS method have a multi-level structure.•Use AFM nanolithography to produce deformation on individual nanofiber.•Structural variation has a direct functional consequence ...in the nanomechanical properties.•Polymer chains become more compact and ordered caused by both compressional stress and shear stress.
Atomic force microscopy (AFM) technique was used to investigate the nanomechanical properties of poly(l-lactide) (PLLA) nanofibers produced by the thermally induced phase separation (TIPS) method. Firstly, AFM-based nanolithography was employed to produce localized deformations on the surface of single PLLA nanofiber, in which the AFM tip served as a nanoscale burin to draw a scratch longitudinally along the nanofiber. Secondly, the morphology and physical properties of the nanofiber before and immediately after the deformation were characterized with AFM and force spectroscopy measurement. During the initial stage of TIPS process, the crystallization of PLLA resulted in a regular arrangement of crystalline domains along the thinner fibrils which then assembled laterally into larger nanofibers. The deformation due to the nanoindentation and plowing with the probe induced structural variation of PLLA nanofibers and led to a functional consequence in their nanomechanical properties. The region after deformation had a higher adhesion force and elastic modulus, probably because the polymer chains became more compact and ordered under both compression and shear stresses.
Bi 2 Se 3 has been widely used as a promising photothermal and photoacoustic agent recently. Herein, two-dimensional (2D) Bi 2 Se 3 nanosheets with different sizes of about 30 nm (Bi 2 Se 3 -30) and ...80 nm (Bi 2 Se 3 -80) have been successfully synthesized via solution-based methods. Both of the Bi 2 Se 3 nanosheets possess high near-infrared (NIR) optical absorption, efficient photothermal conversion and excellent photoacoustic behaviors. Meanwhile, the Bi 2 Se 3 -30 nanosheets perform better. These results indicate the smaller Bi 2 Se 3 nanosheets are more promising for optical diagnostic and photothermal therapy.
Poly(vinylpyrrolidone)‐encapsulated Bi
2
Se
3
nanosheets with a thickness of 1.7 nm and diameter of 31.4 nm are prepared by a solution method. Possessing an extinction coefficient of 11.5 L g
−1
cm
...−1
at 808 nm, the ultrathin Bi
2
Se
3
nanosheets boast a high photothermal conversion efficiency of 34.6% and excellent photoacoustic performance. After systemic administration, the Bi
2
Se
3
nanosheets with the proper size and surface properties accumulate passively in tumors enabling efficient photoacoustic imaging of the entire tumors to facilitate photothermal cancer therapy. In vivo biodistribution studies reveal that they are expelled from the body efficiently after 30 d. The ultrathin Bi
2
Se
3
nanosheets have large clinical potential as metabolizable near‐infrared‐triggered theranostic agents.
Poly(vinylpyrrolidone)-encapsulated Bi sub(2)Se sub(3) nanosheets with a thickness of 1.7 nm and diameter of 31.4 nm are prepared by a solution method. Possessing an extinction coefficient of 11.5 L ...g super(-1) cm super(-1) at 808 nm, the ultrathin Bi sub(2)Se sub(3) nanosheets boast a high photothermal conversion efficiency of 34.6% and excellent photoacoustic performance. After systemic administration, the Bi sub(2)Se sub(3) nanosheets with the proper size and surface properties accumulate passively in tumors enabling efficient photoacoustic imaging of the entire tumors to facilitate photothermal cancer therapy. In vivo biodistribution studies reveal that they are expelled from the body efficiently after 30 d. The ultrathin Bi sub(2)Se sub(3) nanosheets have large clinical potential as metabolizable near-infrared-triggered theranostic agents. Ultrathin Bi sub(2)Se sub(3) nanosheets with a thickness of 1.7 nm and diameter of 31.4 nm are successfully synthesized by a "green" solution-based method. The ultrathin Bi sub(2)Se sub(3) nanosheets deliver excellent photothermal and photoacoustic performance and are well metabolized. These attractive properties render the ultrathin Bi sub(2)Se sub(3) nanosheets promising as a near-infrared-triggered theranostic agents in cancer therapies.
On page 6996, H. Zhang, X.‐F. Yu, and co‐workers describe a simple liquid exfoliation method for production of phosphorene with excellent water stability, controllable size and layer number, as well ...as high yield. The resulting 1–4‐layered phosphorene exhibits layer‐dependent Raman scattering characteristics, which provide a fast and efficient means for in situ determination of the layer number of phosphorene.
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