Molybdenum disulfide (MoS 2 ) with excellent properties has been widely reported in recent years. However, it is a great challenge to achieve p-type conductivity in MoS 2 because of its native stubborn n-type conductivity. Substitutional transition metal doping has been proved to be an effective approach to tune their intrinsic properties and enhance device performance. Herein, we report the growth of Nb-doping large-area monolayer MoS 2 by a one-step salt-assisted chemical vapor deposition method. Electrical measurements indicate that Nb doping suppresses ntype conductivity in MoS 2 and shows an ambipolar transport behavior after annealing under the sulfur atmosphere, which highlights the p-type doping effect via Nb, corresponding to the density functional theory calculations with Fermi-level shifting to valence band maximum. This work provides a promising approach of two-dimensional materials in electronic and optoelectronic applications.
Polyelectrolytes play an important
role in both natural biological
systems and human society, and their synthesis, functional exploration,
and profound application are thus essential for biomimicry and creating
new materials. In this study, we developed an efficient synthetic
methodology for in situ generation of azonia-containing
polyelectrolytes in a one-pot manner by using readily accessible nonionic
reactant in the presence of commercially available cheap ionic species.
The resulting polyelectrolytes are emissive in the solid state and
can readily form luminescent photopatterns with different colors.
The azonia-containing polyelectrolytes possess extraordinary potency
of reactive oxygen species (ROS) generation, enabling them to impressively
kill methicillin-resistant Staphylococcus aureus (MRSA),
a drug resistant superbug, both in vitro and in vivo.
Highly pathogenic Gram-negative bacteria and their drug resistance
are a severe public health threat with high mortality. Gram-negative
bacteria are hard to kill due to the complex cell envelopes with low
permeability and extra defense mechanisms. It is challenging to treat
them with current strategies, mainly including antibiotics, peptides,
polymers, and some hybrid materials, which still face the issue of
drug resistance, limited antibacterial selectivity, and severe side
effects. Together with precise bacteria targeting, synergistic therapeutic
modalities, including physical membrane damage and photodynamic eradication,
are promising to combat Gram-negative bacteria. Herein, pathogen-specific
polymeric antimicrobials were formulated from amphiphilic block copolymers,
poly(butyl methacrylate)-b-poly(2-(dimethylamino)
ethyl methacrylate-co-eosin)-b-ubiquicidin,
PBMA-b-P(DMAEMA-co-EoS)-UBI, in
which pathogen-targeting peptide ubiquicidin (UBI) was tethered in
the hydrophilic chain terminal, and Eosin-Y was copolymerized in the
hydrophilic block. The micelles could selectively adhere to bacteria
instead of mammalian cells, inserting into the bacteria membrane to
induce physical membrane damage and out-diffusion of intracellular
milieu. Furthermore, significant in situ generation
of reactive oxygen species was observed upon light irradiation, achieving
further photodynamic eradication. Broad-spectrum bacterial inhibition
was demonstrated for the polymeric antimicrobials, especially highly
opportunistic Gram-negative bacteria, such as Pseudomona aeruginosa (P. aeruginosa) based on the synergy of physical
destruction and photodynamic therapy, without detectable resistance. In vivo P. aeruginosa-infected knife injury model and burn
model both proved good potency of bacteria eradication and promoted
wound healing, which was comparable with commercial antibiotics, yet
no risk of drug resistance. It is promising to hurdle the infection
and resistance suffered from highly opportunistic bacteria.
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