Huaiyu Wang

Ultrasmall Black Phosphorus Quantum Dots: Synthesis and Use as Photothermal Agents

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.

Biodegradable black phosphorus-based nanospheres for in vivo photothermal cancer therapy

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.

Antibacterial effects and biocompatibility of titanium surfaces with graded silver incorporation in titania nanotubes.

Most commercial dental implants are made of titanium (Ti) because Ti possesses excellent properties such as osseointegration. However, many types of Ti products still suffer from insufficient antibacterial capability and bacterial infection after surgery remains one of the most common and intractable complications. In this study, a dual process encompassing anodization and silver plasma immersion ion implantation (Ag PIII) is utilized to produce titania nanotubes (TiO₂-NTs) containing Ag at different sites and depths. The concentration and depth of the incorporated Ag can be tailored readily by changing the PIII parameters. The Ag-embedded TiO₂-NTs which retain the nanotubular morphology are capable of sterilizing oral pathogens as opposed to pure Ti plates and pristine TiO₂-NTs. Biological assays indicate that the in vitro and in vivo biocompatibility of the sample plasma-implanted at a lower voltage of 0.5 kV (NT-Ag-0.5) is significantly compromised due to the large amount of surface Ag. On the other hand, the sample implanted at 1 kV (NT-Ag-1.0) exhibits unimpaired effects due to the smaller surface Ag accumulation. Sample NT-Ag-1.0 is further demonstrated to possess sustained antibacterial properties due to the large embedded depth of Ag and the technique and resulting materials have large potential in dental implants.

Surface Coordination of Black Phosphorus for Robust Air and Water Stability

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.

Mechanical and biological characteristics of diamond-like carbon coated poly aryl-ether-ether-ketone

Poly aryl-ether-ether-ketone (PEEK) is an alternative to metal alloys in orthopedic applications. Although the polymer provides many significant advantages such as excellent mechanical properties and non-toxicity, it suffers from insufficient elasticity and biocompatibility. Since the elastic modulus of diamond-like carbon (DLC) is closer to that of cortical bone than PEEK, the DLC/PEEK combination is expected to enhance the stability and surface properties of PEEK in bone replacements. In this work, PEEK is coated with diamond-like carbon (DLC) by plasma immersion ion implantation and deposition (PIII&D) to enhance the surface properties. X-ray photoelectron spectrometry (XPS), Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy demonstrate successful deposition of the DLC film on PEEK without an obvious interface due to energetic ion bombardment. Atomic force microscopy (AFM) and contact angle measurements indicate changes in the surface roughness and hydrophilicity, and nanoindentation measurements reveal improved surface hardness on the DLC/PEEK. Cell viability assay, scanning electron microscopy (SEM), and real-time PCR analysis show that osteoblast attachment, proliferation, and differentiation are better on DLC/PEEK than PEEK. DLC/PEEK produced by PIII&D combines the advantages of DLC and PEEK and is more suitable for bone or cartilage replacements.

Biocompatibility and bioactivity of plasma-treated biodegradable poly(butylene succinate).

Poly(butylene succinate) (PBSu), a novel biodegradable aliphatic polyester with excellent processability and mechanical properties, is a promising substance for bone and cartilage repair. However, it typically suffers from insufficient biocompatibility and bioactivity after implantation into the human body. In this work, H(2)O or NH(3) plasma immersion ion implantation (PIII) is conducted for the first time to modify the PBSu surface. Both the treated and control specimens are characterized by X-ray photoelectron spectroscopy, contact angle measurements and atomic force microscopy. The plasma treatments improve the hydrophilicity and roughness of PBSu significantly and the different PIII processes result in similar hydrophilicity and topography. C-OH and C-NH(2) functional groups emerge on the PBSu surface after H(2)O and NH(3) PIII, respectively. The biological results demonstrate that both osteoblast compatibility and apatite formability are enhanced after H(2)O and NH(3) PIII. Furthermore, our results suggest that H(2)O PIII is more effective in rendering PBSu suitable for bone-replacement implants compared to NH(3) PIII.

Ag and Ag/N2 plasma modification of polyethylene for the enhancement of antibacterial properties and cell growth/proliferation.

Polyethylene (PE) is one of the most common materials used for medical implants. However, it usually possesses low biocompatibility and insufficient antibacterial properties. In the work described here, plasma immersion ion implantation (PIII) is employed to implant silver into PE to enhance both its antibacterial properties and its biocompatibility. Our results show that Ag PIII can give rise to excellent antibacterial properties and induces the formation of functional groups such as C-O and C=C. These C-O and C=C groups on the modified surface can trigger the growth of the human fetal osteoblastic cell line (hFOB). Furthermore, combining N(2) and Ag PIII prolongs the antibacterial effects, but nitrogen-containing functional groups such as C-N and C=N created by N(2) co-PIII negatively impact proliferation of hFOB on the surface. According to our experimental investigation on cell proliferation, functional groups such as C-N and C=N created by nitrogen PIII are disadvantageous to cell growth whereas the C-O and C=C groups benefit cell growth. Both the antibacterial activity and biocompatibility of PE can be enhanced by means of the proper plasma surface treatment.

Osteoblast behavior on polytetrafluoroethylene modified by long pulse, high frequency oxygen plasma immersion ion implantation

Polytetrafluoroethylene (PTFE) is a commonly used medical polymer due to its biological stability and other attractive properties such as high hardness and wear resistance. However, the low surface energy and lack of functional groups to interact with the cellular environment have severely limited its applications in bone or cartilage replacements. Plasma immersion ion implantation (PIII) is a proven effective surface modification technique. However, when conducted on polymeric substrates, conventional PIII experiments typically employ a low pulsing frequency and short pulse duration in order to avoid sample overheating, charging, and plasma sheath extension. In this paper, a long pulse, high frequency O(2) PIII process is described to modify PTFE substrates by implementing a shielded grid in the PIII equipment without these aforementioned adverse effects. X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and contact angle measurements are carried out to reveal the surface effects of PTFE after long pulse, high frequency O(2) PIII and the results are compared to those obtained from conventional short pulse, low frequency O(2) PIII, O(2) plasma immersion, and the untreated control samples. Our results show that less oxygen-containing, rougher, and more hydrophobic surfaces are produced on PTFE after long pulse, high frequency O(2) PIII compared to the other 2 treatments. Cell viability assay, ALP activity test, and real-time PCR analysis are also performed to investigate the osteoblast behavior. It is clear that all 3 surface modification techniques promote osteoblast adhesion and proliferation on the PTFE substrates. Improvements on the ALP, OPN, and ON expression of the seeded osteoblasts are also obvious. However, among these treatments, only long pulse, high frequency O(2) PIII can promote the OCN expression of osteoblasts when the incubation time is 12 days. Our data unequivocally disclose that the long pulse, high frequency O(2) PIII technique is better than the other two types of traditional plasma treatment in the development of PTFE for bone or cartilage repair.

Bimodal optical diagnostics of oral cancer based on Rose Bengal conjugated gold nanorod platform

Early detection of cancer often requires time consuming protocols and expensive instrumentation. To address these limitations, a Rose Bengal conjugated gold nanorod (RB-GNR) platform is developed for optical detection of cancer cells. The GNRs are modified by poly(allylamine hydrochloride) and conjugated with RB molecules to produce RB-GNRs which exhibit strong optical absorption in the near-infrared (NIR) region, good stability in aqueous solution, low cytotoxicity, and high specificity to oral cancer cells. The label-free sensing assay utilizes RB-GNRs as the sensing probe and by monitoring the aggregation-induced red-shift in the NIR absorption wavelength, specific and quantitative analysis of the oral cancer cell lysate is accomplished down to a detection limit of 2000 cells/mL. By employing the RB-GNRs as an imaging probe, an imaging assay is established on a home-made NIR absorption imaging system. Based on the NIR absorption by the RB-GNRs specifically conjugated with the oral cancer cells, multi-channel, rapid and quantitative detection of oral cancer cells is demonstrated. The high sensitivity and specificity of the RB-GNR platform as demonstrated by the two complementary assays provide non-invasive optical diagnostics of oral cancer cells enabling convenient screening and monitoring.

Evaporative Self-Assembly of Gold Nanorods into Macroscopic 3D Plasmonic Superlattice Arrays.

Millimeter-scale 3D superlattice arrays composed of dense, regular, and vertically aligned gold nanorods are fabricated by evaporative self-assembly. The regular organization of the gold nanorods into a macroscopic superlattice enables the production of a plasmonic substrate with excellent sensitivity and reproducibility, as well as reliability in surface-enhanced Raman scattering. The work bridges the gap between nanoscale materials and macroscopic applications.