Custom-made PEI/exfoliated-MoS 2 nanocomposite ultrafiltration membranes for separation of bovine serum albumin and humic acid

MoS2 nanoflowers surface decorated with CuS nanorods and carbon dots for fluorescent and ultrasound imaging in cancer therapy

In recent years, the design of various ultrasound responsive echogenic nanomaterials offers many advantages such as deep tissue penetration, high signal intensity, colloidal stability, biocompatibility and less expensive for ultrasound-based cancer cell imaging while providing the option to monitor the progress of tumor volume during the treatment. Further, the ability of nanomaterials to combine photo-thermal therapy (PTT) and chemotherapy has opened a new avenue in the development of cancer theranostics for synergistic cancer therapy. Herein, we report MoS2 nanoflowers (NFs) surface decorated with CuS nanorods (NRs) and folic acid-derived carbon dots (FACDs) using cystine-polyethyleneimine (PEI) linker for PTT-chemotherapy. The size of NFs was found to be 350 ± 50 nm which increased to 500 ± 50 nm after surface decoration. The morphology of MoS2 NFs before and after surface decoration was investigated using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and UV-Vis-NIR spectroscopy. The photo-thermal heat generation was found to be increasing as a function of the concentration of NFs. The encapsulation efficiency of doxorubicin (DOX) and photo-thermal conversion efficiency (PCE) for surface-decorated MoS2 NFs (MoS2@CuS/FACDs NFs) was estimated to be 42 and 44 %, respectively. The surface decoration of CuS NRs and FACDs on MoS2 NFs not only improved the anticancer activity but also increased the signal intensity in ultrasound and fluorescence imaging of cancer cells. The MoS2@CuS/FACDs NFs exhibited excellent cytotoxicity against MDA-MB-231 cancer cells. Hence, the hybrid system demonstrated here showed high potential for use as a combined probe for non-invasive ultrasound imaging and fluorescence imaging for PTT-chemotherapy.

The enhancement of dye filtration performance and antifouling properties in amino-functionalized bentonite/polyvinylidene fluoride mixed matrix membranes

Trade-off issue and membrane fouling remain two major issues in the utilization of membrane technology for the water treatment due to reduced membrane permeability and lifetime. In our study, we employed 3-aminopropyltriethoxysilane modified bentonite (BNTAPS) as an anti-fouling modifier to prepare polyvinylidene fluoride (PVDF)-based membranes via the phase inversion method. The effects of BNTAPS concentration on the physical, mechanical, morphological, and filtration performance of the hybrid membranes have been investigated. It was found that the addition of BNTAPS improved the hydrophilicity of the membrane revealed by the decreased water contact angle. Consequently, the pure water flux of PVDF membrane containing 0.5% BNTAPS (PVDF/BNTAPS0.5%) increased to 35.5 L m^-2 h^-1. Moreover, the PVDF/BNTAPS membrane showed a smaller pore diameter and porosity compared to pristine PVDF. The membrane performance evaluation was carried out using cationic and anionic dyes, i.e., methylene blue (MB) and acid yellow (AY17), respectively. Our study revealed that the rejection of each dye was slightly increased for the PVDF/BNTAPS0.5%. However, the flux recovery rate of the PVDF/BNTAPS membrane significantly improved, which directly prolonged the membrane lifetime.

Tailoring Morphology and Properties of Tight Utrafiltration Membranes by Two-Dimensional Molybdenum Disulfide for Performance Improvement

To enhance the permeation and separation performance of the polyethersulfone (PES) tight ultrafiltration (TUF) membrane, two-dimensional molybdenum disulfide (MoS2) was applied as a modifier in low concentrations. The influence of different concentrations of MoS2 (0, 0.25, 0.50, 1.00, and 1.50 wt%) on TUF membranes was investigated in terms of morphology, mechanical strength properties, permeation, and separation. The results indicate that the blending of MoS2 tailored the microstructure of the membrane and enhanced the mechanical strength property. Moreover, by embedding an appropriate amount of MoS2 into the membrane, the PES/MoS2 membranes showed improvement in permeation and without the sacrifice of the rejection of bovine serum protein (BSA) and humic acid (HA). Compared with the pristine membrane, the modified membrane embedded with 0.5 wt% MoS2 showed a 36.08% increase in the pure water flux, and >99.6% rejections of BSA and HA. This study reveals that two-dimensional MoS2 can be used as an effective additive to improve the performance and properties of TUF membranes for water treatment.

High-responsivity photodetector based on scrolling monolayer MoS2hybridized with carbon quantum dots

The monolayer MoS₂based photodetectors have been widely investigated, which show limited photoelectric performances due to its low light absorption and uncontrollable adsorbates. In this paper, we present a MoS₂-based hybrid nanoscrolls device, in which one-dimensional nanoscrollsof MoS₂is hybridized with carbon quantum dots (CQDs). This device architecture effectively enhanced the photodetection performance. The photoresponsivity and detectivity values of MoS₂/CQDs-NS photodetectors are respectively 1793 A W^-1and 5.97 × 10¹²Jones, which are 830-fold and 268-fold higher than those of pristine MoS₂under 300 nm illumination atV_ds = 5 V. This research indicates a significant progress in fabricating high-performance MoS₂photodetectors.

2D MoS2 nanoplatelets for fouling resistant membrane surface

2D Molybdenum disulfide (MoS₂) nanoplatelets were synthesized via a green bottom-up strategy using non-toxic l-Cysteine as sulfur source. Thehydrophobic MoS₂ nanoplatelets assisted by hydrophilic 3-(3, 4-dihydroxyphenyl)-l-alanine (l-DOPA) were coated on a thin film composite nanofiltration (TFC-NFG) membrane. The accelerated fouling experiments were conducted by usingbovine serum albumin (BSA) asmodel organic foulant,and MoS₂ coated membrane demonstrated excellent resistance with almost no flux decline within first hour of filtration, whereas the uncoated membrane showed flux decline immediately from the beginning of the experiment. After 5-hour filtration, the flux reduced by only 26% for MoS₂ coated membrane with a higher flux recovery rate of 85.4% after washing by de-ionized (DI) water, whereas 45% flux decline was observed for uncoated membrane with lower flux recovery of 68%.These antifouling effects attributed by MoS₂coated membrane were underpinned by combined unique interfacial properties offered by 2D tri-atomic layered MoS₂morphology including dispersive surface tension, reduced surface roughness, weaker MoS₂-foulant interactive forces, and negatively charged surface. This research positively confirms the role of 2D MoS₂ nanoplatelets as an anti-fouling coating on membranes and brings up more possibility for applying other nanomaterials in 2D family in water applications such as desalination and water treatment.

Polydopamine-Assisted Two-Dimensional Molybdenum Disulfide (MoS2)-Modified PES Tight Ultrafiltration Mixed-Matrix Membranes: Enhanced Dye Separation Performance

Tight ultrafiltration (TUF) membranes with high performance have attracted more and more attention in the separation of organic molecules. To improve membrane performance, some methods such as interface polymerization have been applied. However, these approaches have complex operation procedures. In this study, a polydopamine (PDA) modified MoS₂ (MoS₂@PDA) blending polyethersulfone (PES) membrane with smaller pore size and excellent selectivity was fabricated by a simple phase inversion method. The molecular weight cut-off (MWCO) of as-prepared MoS₂@PDA mixed matrix membranes (MMMs) changes, and the effective separation of dye molecules in MoS₂@PDA MMMs with different concentrations were obtained. The addition amount of MoS₂@PDA increased from 0 to 4.5 wt %, resulting in a series of membranes with the MWCO values of 7402.29, 7007.89, 5803.58, 5589.50, 6632.77, and 6664.55 Da. The MWCO of the membrane M3 (3.0 wt %) was the lowest, the pore size was defined as 2.62 nm, and the pure water flux was 42.0 L m⁻² h⁻¹ bar⁻¹. The rejection of Chromotrope 2B (C2B), Reactive Blue 4 (RB4), and Janus Green B (JGB) in aqueous solution with different concentrations of dyes was better than that of unmodified membrane. The separation effect of M3 and M0 on JGB at different pH values was also investigated. The rejection rate of M3 to JGB was higher than M0 at different pH ranges from 3 to 11. The rejection of M3 was 98.17–99.88%. When pH was 11, the rejection of membranes decreased with the extension of separation time. Specifically, at 180 min, the rejection of M0 and M3 dropped to 77.59% and 88.61%, respectively. In addition, the membrane had a very low retention of salt ions, Nacl 1.58%, Na₂SO₄ 10.52%, MgSO₄ 4.64%, and MgCl₂ 1.55%, reflecting the potential for separating salts and dyes of MoS₂@PDA/PES MMMs.

The hierarchical flower-like MoS2 nanosheets incorporated into PES mixed matrix membranes for enhanced separation performance

Membrane fouling is an issue of concern due to the hydrophobic properties of polyethersulfone (PES) membrane when applied in water treatment. In this work, a facile hydrothermal method was utilized to synthesize hierarchical flower-like structured molybdenum disulfide nanosheets (HF-MoS2 NSs) that then incorporated into PES membranes as composite membranes. We characterized their permeability, the separation performance, the antifouling performance, and the antibacterial activity systematically. Results showed that composite membranes exhibited a better pure water flux (286 LMH/bar) at the HF-MoS₂ NSs content of 0.4 wt%, which was 1.8 times higher than the control membrane. Also, composite PES membranes achieved 98.2% and 96.9% rejection of BSA and HA in comparison with the control PES membrane (87.3%, and 84.5%, respectively). Compare to the control PES membrane, the flux recovery ratio of the composite membrane increased from 69% to 88% for BSA fouling and increased from 84% to 93% for HA fouling. The retention rate for the organic dyes also improved slightly after HF-MoS2 NSs incorporation into the membrane. Additionally, the composite membranes exhibited a relatively high antibacterial activity against E. coli and B. subtilis with antibacterial rates of 67.8% and 82.5%, respectively. In conclusion, HF-MoS2 NSs incorporated composite membranes were shown to have outstanding filtration performance and could be a promising candidate for practical application in water filtration.

Cellulose acetate ultrafiltration membranes customized with bio-inspired polydopamine coating and in situ immobilization of silver nanoparticles

Schematic representation of the surface modification of cellulose acetate membranes with self-polymerized dopamine and in situ immobilization of AgNPs.

Fabrication of anti-fouling PVDF nanocomposite membranes using manganese dioxide nanospheres with tailored morphology, hydrophilicity and permeation

Manganese dioxide (MnO₂) nanospheres were prepared by a facile hydrothermal technique and their influence on the permeation and antifouling properties of poly(vinylidene fluoride) (PVDF) ultrafiltration (UF) membranes was investigated.