Peng Fei Gao

Antibacterials loaded electrospun composite nanofibers: release profile and sustained antibacterial efficacy

Synthetic polyacrylonitrile (PAN)/agar composite nanofibers were fabricated by introducing agar during the electrospinning process, and it was found that the nanofibers could be used for efficient, controlled drug release. Hydrophilic drugs such as ampicillin (AMC) were successfully encapsulated inside the agar, allowing the formation of uniform and smooth AMC/agar/PAN composite nanofibers. Cell viability assays showed that the as-prepared agar/PAN composite nanofibers had a good biocompatibility, and the antibacterial activity of the designed drug delivery system was investigated against Gram negative E. coli with a sustained release profile. The good biocompatibility and enhanced thermal properties—as well as the long-lasting antibacterial activity—of these agar/PAN composite nanofiber-containing drugs indicate their significant promise for a variety of potential medicinal applications. We believe that this approach could serve as a model technique in the fields of drug delivery and controlled release when considering the compatibility between polymers and drugs.

Porous hollow CuS nanospheres with prominent peroxidase-like activity prepared in large scale by a one-pot controllable hydrothermal step

CuS materials with peroxidase activity have been prepared but greatly limited by the large dosage and low peroxidase activity. In this paper, porous hollow CuS nanospheres with a variety of sizes were fabricated by one-pot method based on a facile template-assisted hydrothermal approach. The size of the porous hollow CuS nanospheres could be simply tuned by adjusting the molar ratios of reactants, the reaction temperature, and time. The as-prepared porous hollow CuS nanospheres were demonstrated to exhibit more prominent intrinsic peroxidase-like activity using TMB as a peroxidase substrate in the presence of hydrogen peroxide (H2O2). This is a significant comparison to previous reports, demonstrating that the new developed synthetic porous hollow CuS nanospheres can be a new kind of candidate for peroxidase mimics, and the nanospheres are promising for applications in biosensors, environmental monitoring, and so on.

A portable RGB sensing gadget for sensitive detection of Hg2+ using cysteamine-capped QDs as fluorescence probe

A facile one-pot method was proposed to synthesis cysteamine capped CdTe QDs with a high quantum yield 30%. In the synthesis process, nitrogen protection, ultrasonic treatment, and light irradiation were unnecessary. Additionally, potassium tellurite was used instead of Te powder as Te source, avoiding of the time-consuming Te powder dissolution process. The prepared QDs were found to be Hg2+ sensitive. The detection linear range for Hg2+ was from 5 to 300nM, and the detection limit was calculated to be 1nM. The detection mechanism was mainly ascribed to the electron transfer from cysteamine capped QDs to Hg2+, resulting in a fluorescence quenching phenomenon. In addition, we developed a portable RGB sensing gadget with the QDs as fluorescence probe for Hg2+ detection, and the linear range was from 5 to 200nM. Furthermore, the gadget was applied for Hg2+ detection in tap water sample. The results showed that the average recoveries in real tap water sample were in the range from 97.2% to 115.3%, which indicated that accuracy and precision were satisfactory for practical application requirements.

Biomolecules-conjugated nanomaterials for targeted cancer therapy

Biomolecules perform vital functions in biology. These functional biomolecules with diverse modifications hold great promise for further applications in bioanalysis and cancer therapy. However, these functional biomolecules face challenges, especially in the field of drug delivery for cancer therapy. For example, functional biomolecules are typically unstable when taken up by cells, as they are easily digested by enzymes. To address this obstacle, nanomaterials have been employed as drug carriers or vehicles, which are powerful nanoplatforms for imaging and cancer treatment. Multifunctionality of these nanoplatforms offers great advantages over conventional reagents, including targeting to a diseased site to minimize systemic toxicity, and the ability to solubilize hydrophobic or labile drugs to improved pharmacokinetics. In this review, we summarize typical functional biomolecule-conjugated nanomaterials for targeting drug delivery. Under the appropriate conditions, targeted drug delivery can be achieved from a high density of biomolecules that are bound to the surface of nanomaterials, resulting in a high affinity for the targets. The high density of biomolecules then leads to a high local concentration, being able to prevent degradation by enzymes. Furthermore, biomolecule-nanomaterial conjugates have been identified to enter cells more easily than free biomolecules, and controllable drug release can then be obtained by a response to a stimulus, such as redox, pH, light, thermal, enzyme-trigged strategies. Now and in the future, with the development of artificial biomolecules as well as nanomaterials, targeted drug delivery based on elegant biomolecule-nanomaterial conjugation approaches is expected to achieve great versatility, additional functions, and further advances.

Visual Identification of Light-Driven Breakage of the Silver-Dithiocarbamate Bond by Single Plasmonic Nanoprobes

Insight into the nature of metal-sulfur bond, a meaningful one in life science, interface chemistry and organometallic chemistry, is interesting but challenging. By utilizing the localized surface plasmon resonance properties of silver nanoparticles, herein we visually identified the photosensitivity of silver-dithiocarbamate (Ag-DTC) bond by using dark field microscopic imaging (iDFM) technique at single nanoparticle level. It was found that the breakage of Ag-DTC bond could be accelerated effectively by light irradiation, followed by a pH-dependent horizontal or vertical degradation of the DTC molecules, in which an indispensable preoxidation process of the silver was at first disclosed. These findings suggest a visualization strategy at single plasmonic nanoparticle level which can be excellently applied to explore new stimulus-triggered reactions, and might also open a new way to understand traditional organic reaction mechanisms.

Insight into a reversible energy transfer system

Resonance energy transfer (RET) processes have wide applications; these processes involve a unidirectional energy transfer from a particular donor to a particular acceptor. Here, we report a plasmonic resonance energy transfer (PRET), which occurs from the surface of gold nanoparticles to fluorescent organic dyes, and coexists with a nanometal surface energy transfer (NSET) that operates in the reverse direction. The coexistence of both PRET and NSET in opposite directions means that the roles of both donor and acceptor can be interchanged, which could be identified by using spectrofluorometric measurements and light scattering dark field microscopic imaging. The experimental data could be further theoretically supported using Persson and Langs model, the quasi-static approximation and finite-difference time-domain simulation. Moreover, disruption of the PRET process by altering the energy transfer pairs suggests that interactions occur inside the reversible energy transfer system, which manifest by increasing the fluorescence quenching efficiency of the NSET process.

Boron and nitrogen co-doped single-layered graphene quantum dots: a high-affinity platform for visualizing the dynamic invasion of HIV DNA into living cells through fluorescence resonance energy transfer

High-affinity binding of carbon nanomaterials with nucleobases, which is still a challenge, is the basis for DNA directed assembly and sensing. In this work, boron and nitrogen co-doped single-layered graphene quantum dots (BN-SGQDs) are designed as a high-affinity platform for nucleic acid detection and imaging in living cells, which has been confirmed by density functional theory (DFT) simulation and experiments. Owing to their excellent absorption and photoluminescence ability, the high quantum yield (QY 36.5%) yellow fluorescent BN-SGQDs could act as an energy donor in the fluorescence resonance energy transfer (FRET) process for nucleic acid detection. Furthermore, this BN-SGQD based sensing platform has been successfully adopted to visualize the dynamic invasion of human immunodeficiency virus (HIV) DNA into HeLa cells. The high-affinity platform has shown potential for biosensing in complicated biological samples.

Color Encoded Assays for the Simultaneous Quantification of Dual Cancer Biomarkers

For the first time, the scattering light of noble nanoparticles was applied for the simultaneous detection of dual cancer biomarkers. Two nanoprobes with dual scattering light colors were used for the simultaneous imaging of alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) based on the sandwich-type immunoassay. Since AFP can combine anti-AFP-modified gold nanoparticles, which have green scattering light under the dark-field microscopic imaging (iDFM) technique, while CEA can conjugate anti-CEA-immobilized silver nanoparticles, which have blue scattering light, the simultaneous determination of AFP and CEA can be achieved by separately counting the number of green and blue light spots in iDFM. The mutual interference between the detection processes of AFP and CEA in the dual detection was investigated, and a negligible interference was found when the concentration of the antigen was in the range of 0.5-10 ng/mL, indicating the practicability of the simultaneous sensitive detection of dual targets. Furthermore, AFP and CEA in serum samples were also quantified directly without additional sample pretreatment, demonstrating the potential applications of the developed method in clinical diagnosis.