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Citric acid (CA) was used in a thermally induced phase separation (TIPS) process to improve the surface hydrophilicity and cell affinity of PLLA nano-fibrous scaffolds. The evolution of architecture, structure and physicochemical properties of the scaffold after modification has been investigated. Cell viability, adhesion, proliferation and osteogenic differentiation were characterized to evaluate the cytocompatibility and biological properties of PLLA nano-fibrous scaffolds. Citric acid interacted with PLLA through hydrogen bond association and the introduction of strong polar groups (–COOH) on the PLLA surface improved its hydrophilicity with the contact angle decreasing to a suitable range for cell adhesion and spreading. The cell exhibited extensive spreading on the CA modified PLLA scaffolds with many cellular protrusions interacting with nanofibers. Furthermore, such a modification significantly increased the cell proliferation rate, enhanced the alkaline phosphatase (ALP) activity and bone-related gene expression (ALP, OCN, COL I and Runx2) of mBMSCs along with cell development. The results demonstrate a promising modification method to promote applications of PLLA-based scaffolds.

Near-infrared (NIR) light-responsive shape-memory composites have shown great potential in various biomedical applications due to their amazing remote actuation property. However, most of them are bioinert and restricted in NIR-I biological window. Here, we developed a new biodegradable NIR-II-responsive shape memory composite by the incorporation of CaSiCu4O10 nanosheets (CUP NSs) into shape memory polymer of poly (D, L-lactide-co-trimethylene carbonate) (PDLLA-co-TMC, denoted as PT). The as-prepared CUP/PT composites possessed outstanding shape memory performance upon low power NIR-II laser irradiation (1064 nm, 0.4 W·cm−2), offering the possibility of deep-tissue applications. Moreover, due to the sustained release of bioactive Cu2+ and SiO44- ions, the composites exhibited strong stimulation of angiogenesis both in vitro and in vivo. Our work demonstrated the promising potential of CUP/PT composites as NIR-II light-responsive biomaterials with enhanced tissue reconstruction ability, especially for wound healing.

Bi2Se3 has been widely used as a promising photothermal and photoacoustic agent recently. Herein, two-dimensional (2D) Bi2Se3 nanosheets with different sizes of about 30 nm (Bi2Se3-30) and 80 nm (Bi2Se3-80) have been successfully synthesized via solution-based methods. Both of the Bi2Se3 nanosheets possess high near-infrared (NIR) optical absorption, efficient photothermal conversion and excellent photoacoustic behaviors. Meanwhile, the Bi2Se3-30 nanosheets perform better. These results indicate the smaller Bi2Se3 nanosheets are more promising for optical diagnostic and photothermal therapy.

In breast cancer chemophotothermal therapy, it is a great challenge for the development of multifunctional nanoagents for precision targeting and the effective treatment of tumors, especially for metastasis. Herein, we successfully design and synthesize a multifunctional black phosphorus (BP)-based nanoagent, BP/DTX@PLGA, to address this challenge. In this composite nanoagent, BP quantum dots (BPQDs) are loaded into poly(lactic-co-glycolic acid) (PLGA) with additional conjugation of a chemotherapeutic agent, docetaxel (DTX). The in vivo distribution results demonstrate that BP/DTX@PLGA shows striking tropism for targeting both primary tumors and lung metastatic tumors. Moreover, BP/DTX@PLGA exhibits outstanding controllable chemophotothermal combinatory therapeutics, which dramatically improves the efficacy of photothermal tumor ablation when combined with near-light irradiation. Mechanistically, accelerated DTX release from the nanocomplex upon heating and thermal treatment per se synergistically incurs apoptosis-dependent cell death, resulting in the elimination of lung metastasis. Meanwhile, in vitro and in vivo results further confirm that BP/DTX@PLGA possesses good biocompatibility. This study provides a promising BP-based multimodal nanoagent to constrain cancer metastasis.

Photothermal therapy (PTT) offers many advantages such as high efficiency and minimal invasiveness, but clinical adoption of PTT nanoagents have been stifled by unresolved concerns such as the biodegradability as well as long-term toxicity. Herein, poly (lactic-co-glycolic acid) (PLGA) loaded with black phosphorus quantum dots (BPQDs) is processed by an emulsion method to produce biodegradable BPQDs/PLGA nanospheres. The hydrophobic PLGA not only isolates the interior BPQDs from oxygen and water to enhance the photothermal stability, but also control the degradation rate of the BPQDs. The in vitro and in vivo experiments demonstrate that the BPQDs/PLGA nanospheres have inappreciable toxicity and good biocompatibility, and possess excellent PTT efficiency and tumour targeting ability as evidenced by highly efficient tumour ablation under near infrared (NIR) laser illumination. These BP-based nanospheres combine biodegradability and biocompatibility with high PTT efficiency, thus promising high clinical potential., Black phosphorus is a biodegradable 2D material that has attracted growing interest in biomedicine. Here, the authors carry out in vitro and in vivo experiments to demonstrate that nanospheres loaded with black-phosphorus quantum dots perform as promising phothermal cancer therapy agents.

Poly(vinylpyrrolidone)-encapsulated Bi2 Se3 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 Bi2 Se3 nanosheets boast a high photothermal conversion efficiency of 34.6% and excellent photoacoustic performance. After systemic administration, the Bi2 Se3 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 Bi2 Se3 nanosheets have large clinical potential as metabolizable near-infrared-triggered theranostic agents.

A titanium sulfonate ligand is synthesized for surface coordination of black phosphorus (BP). In contrast to serious degradation observed from the bare BP, the BP after surface coordination exhibits excellent stability during dispersion in water and exposure to air for a long period of time, thereby significantly extending the lifetime and spurring broader application of BP.

As a prominent member of two dimensional (2D) materials, MXenes have shown encouraging photophysical properties and so there is highly desirability to explore their phototherapeutic potential in cancer. Herein, we demonstrate a facile top-down strategy for the synthesis of nitride-based MXene, titanium nitride quantum dots (Ti2N QDs) in solution. With a size of around 5 nm, the obtained Ti2N QDs exhibit extraordinarily high photothermal conversion efficiency under laser irradiation in both first and second near-infrared (NIR) biowindows (NIR-I, 808 nm, 48.62%; and NIR-II, 1064 nm, 45.51%). In vitro and in vivo assessments demonstrate that the Ti2N QDs possess excellent biocompatibility, photoacoustic (PA) effect, and photothermal therapy (PTT) efficiency. Moreover, the Ti2N QDs showing obvious aggregation in tumors after 4 h post-injection, which enables facilitate PA imaging-guided PTT in both NIR-I/II biowindows without noticeable toxicity. Encouragingly, the Ti2N QDs with appropriate degradation property also show an applicable excretion rate from the body in vivo, which ensures sufficient stability in circulation to accomplish therapeutics roles and then can be smoothly discharged from the body after that. These results indicate the high potential of biodegradable Ti2N QDs in PA imaging-guided PTT in both NIR-I/II biowindows for precision cancer treatment.

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.

As new 2D layered nanomaterials, Bi2 O2 Se nanoplates have unique semiconducting properties that can benefit biomedical applications. Herein, a facile top-down approach for the synthesis of Bi2 O2 Se quantum dots (QDs) in a solution is described. The Bi2 O2 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 Bi2 O2 Se QDs possess excellent photoacoustic (PA) performance and photothermal therapy (PTT) efficiency. After systemic administration, the Bi2 O2 Se QDs accumulate passively in tumors enabling efficient PA imaging of the entire tumors to facilitate imaging-guided PTT without obvious toxicity. Furthermore, the Bi2 O2 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 Bi2 O2 Se QDs as a biodegradable multifunctional agent in medical applications.

Self-assembled monolayers with different terminal chemical groups including thiol ( SH), methyl ( CH3), carboxyl ( COOH) and hydroxyl ( OH) were employed as substrates for the culture of hepatoma cells (HepG2s). X-ray photoelectron spectroscopy and atomic force microscopy confirmed the similar density of different functional groups occupation. The adhesion and proliferation of cancer cells exhibited significant difference on different surfaces. The HepG2s adhered to CH3 surfaces but exhibited the smallest contact area with mostly rounded morphology, while those on SH surfaces exhibited the largest contact area with extensive spreading. The proliferation of HepG2s in prolonged culture was significantly inhibited on CH3 surface. Cells on other surfaces of various chemical groups proliferated at different levels. After 7 days of culture, the proliferation of HepG2s on the different surfaces followed the trend: OH ≈ COOH > SH ≫ CH3. Due to the strong hydrophobic property, the CH3 group inhibited the cell adhesion, which led to the death of cancer cells. Compared with other chemical functional groups, the CH3 group exhibited its unique effect on the fate of cancer cells, providing a potential way on prevention and treatment of liver cancer.

The surface morphology, crystalline structure and nanomechanical properties of poly( l -lactide) (PLLA) samples prepared via thermally induced phase separation (TIPS) process have been investigated by scanning electron microscopy (SEM), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), wide-angle X-ray diffraction (WAXD), atomic force microscopy (AFM), force spectroscopy and nanoindentation. Typical nanofibrous scaffold was obtained at −24 °C (NF sample) while a denser matrix with some plateletlike structure was obtained at 15 °C (PL sample). The NF sample has a higher crystallinity with α′-form crystals while the PL sample has α-form crystals embedded in a largely amorphous matrix. The two kinds of samples have differences in the chain conformation with a more restricted backbone vibration and stiffened segmental motion in NF samples. The NF samples have a higher adhesion force although both samples showed a heterogeneous distribution of adhesion force on the surface based on force spectroscopy analysis. The alternating distribution of domains with higher and lower adhesion force exhibited a banded pattern on PLLA nanofibre. This pattern is proposed to reflect the distribution of crystal-rich and amorphous-rich domains in the semicrystalline samples. AFM-based nanoindentation test indicated that the nanofibrous NF samples can have more significant plastic deformation and creep than the largely amorphous PL samples. The sliding of the crystal-rich domains along the fibrils would account for this increased plasticity of the nanofiber.

Black phosphorus quantum dots (BPQDs) were synthesized using a liquid exfoliation method that combined probe sonication and bath sonication. With a lateral size of approximately 2.6 nm and a thickness of about 1.5 nm, the ultrasmall BPQDs exhibited an excellent NIR photothermal performance with a large extinction coefficient of 14.8 L g(-1) cm(-1) at 808 nm, a photothermal conversion efficiency of 28.4%, as well as good photostability. After PEG conjugation, the BPQDs showed enhanced stability in physiological medium, and there was no observable toxicity to different types of cells. NIR photoexcitation of the BPQDs in the presence of C6 and MCF7 cancer cells led to significant cell death, suggesting that the nanoparticles have large potential as photothermal agents.