Sorting Short Fragments of Single-Stranded DNA with an Evolving Electric Double Layer

We demonstrate a new procedure for separation of single-stranded DNA (ssDNA) fragments that are anchored to the surface of a gold electrode by end hybridization. The new separation procedure takes advantage of the strong yet evolving nonuniform electric field near the gold surface in contact with a buffer solution gradually being diluted with deionized water. Separation of short ssDNA fragments is demonstrated by monitoring the DNA at the gold surface with <i>in situ</i> fluorescence measurement. The experimental results can be rationalized with a simple theoretical model of electric double layer that relates the strength of the surface pulling force to the ionic concentration of the changing buffer solution

Au-PLGA Hybrid Nanoparticles with Catalase-Mimicking and near-Infrared Photothermal Activities for Photoacoustic Imaging-Guided Cancer Therapy

Imaging-guided diagnosis and therapy has been highlighted in the area of nanomedicines. However, integrating multiple functions with high performance in one theranostic (“all-in-one”) still presents considerable challenges. Here, “all-in-one” nanoparticles with drug-loading capacity, catalase-mimetic activity, photoacoustic (PA) imaging ability and photothermal properties were prepared by decorating Au nanoparticles on doxorubicin (DOX) encapsulated poly­(lactic-<i>co</i>-glycolic acid) (PLGA) vehicle. The results revealed that the as-prepared Au-PLGA hybrid nanoparticles possessed high photothermal conversion efficiency of up to approximately 69.0%, meanwhile their strong acoustic generation endowed them with efficient PA signal sensing for cancer diagnosis. On an 808 nm laser irradiation, the O₂ generation, DOX release profile and reactive oxygen species (ROS) level were all improved, which were beneficial to relieving tumor hypoxia and enhanced the cancer chemo/PTT combined therapy. Overall, the multifunctional Au-PLGA hybrid nanoparticles with these integrated advantages shows promise in PA imaging-guided diagnosis and synergistic tumor ablation

Biomimicry Enhances Sequential Reactions of Tethered Glycolytic Enzymes, TPI and GAPDHS

<div><p>Maintaining activity of enzymes tethered to solid interfaces remains a major challenge in developing hybrid organic-inorganic devices. In nature, mammalian spermatozoa have overcome this design challenge by having glycolytic enzymes with specialized targeting domains that enable them to function while tethered to a cytoskeletal element. As a step toward designing a hybrid organic-inorganic ATP-generating system, we implemented a biomimetic site-specific immobilization strategy to tether two glycolytic enzymes representing different functional enzyme families: triose phosphoisomerase (TPI; an isomerase) and glyceraldehyde 3-phosphate dehydrogenase (GAPDHS; an oxidoreductase). We then evaluated the activities of these enzymes in comparison to when they were tethered via classical carboxyl-amine crosslinking. Both enzymes show similar surface binding regardless of immobilization method. Remarkably, specific activities for both enzymes were significantly higher when tethered using the biomimetic, site-specific immobilization approach. Using this biomimetic approach, we tethered both enzymes to a single surface and demonstrated their function in series in both forward and reverse directions. Again, the activities in series were significantly higher in both directions when the enzymes were coupled using this biomimetic approach versus carboxyl-amine binding. Our results suggest that biomimetic, site-specific immobilization can provide important functional advantages over chemically specific, but non-oriented attachment, an important strategic insight given the growing interest in recapitulating entire biological pathways on hybrid organic-inorganic devices.</p></div

Design of recombinant proteins and verification of purified His-TPI and His-GAPDHS.

<p>a) A hexahistidine tag was introduced to modify the amino terminal, germ cell-specific domain (gcs) of sperm TPI. b) SDS-PAGE showing representative coomassie brilliant blue (CBB) protein staining and immunoblot analysis of purified His-TPI with antibodies against the His-tag (His) and the protein (TPI). c) A hexahistidine tag replaced the amino-terminal proline-rich domain (PRD) of GAPDHS. d) SDS-PAGE showing representative protein staining (CBB) and immunoblot analysis of purified His-GAPDHS with antibodies against the His-tag (His) and the protein (GAPDHS).</p

Mechanistic Insight into the Light-Irradiated Carbon Capsules as an Antibacterial Agent

Infections caused by bacteria are a growing global challenge for public health as bacteria develop resistance, which will cause the failure of anti-infective treatment eventually. An effective alternative strategy to traditional antibacterial therapy is utilizing reactive oxygen species (ROS) to kill bacteria. Here, we report a simple route to prepare PEGylated nitrogen-doped carbon capsules (PEG-N-CCs) as an antibacterial agent. The PEG-N-CCs can translate near-infrared light (NIR) into heat and produce a high concentration of ROS triggered by NIR irradiation. Both heating and ROS are critical to destroy the outer membranes and rupture cell bodies, causing DNA fragmentation and glutathione oxidation both in Gram-negative Escherichia coli, Gram-positive Staphylococcus aureus, and their multidrug-resistant strains. Moreover, PEG-N-CCs plus NIR irradiation can efficiently scavenge the existing biofilms and prevent the formation of new biofilms, killing planktonic bacteria as well as those within the biofilm. Our studies prove that the PEG-N-CCs plus NIR irradiation can provide a simple and effective platform for combating bacteria, employing carbon nanomaterials as an antibacterial alternative for treatment of infectious diseases

Tumor Catalytic–Photothermal Therapy with Yolk–Shell Gold@Carbon Nanozymes

Nanozymes, as a new generation of artificial enzymes, offer great opportunities in biomedical engineering and disease treatment. Synergizing the multiple intrinsic functions of nanozymes can improve their performance in biological systems. Here, we report a novel nanozyme with yolk–shell structure fabricated by combining a single gold nanoparticle core with a porous hollow carbon shell nanospheres (Au@HCNs). Au@HCNs exhibited enzyme-like activities similar to horseradish peroxidase and oxidase under an acidic environment, showing the ability of ROS generation. More importantly, the ROS production of Au@HCNs was significantly improved upon 808 nm light irradiation by the photothermal effect, which is often used for tumor therapy. Cellular and animal studies further demonstrated that the efficient tumor destruction was achieved through the combination of light-enhanced ROS and photothermal therapy. These results implied that the intrinsic enzyme-like activity and photothermal conversion of nanozymes can be synergized for efficient tumor treatment, providing a proof-of-concept of tumor catalytic–photothermal therapy based on nanozymes

Properties of recombinant proteins.

<p>Enzyme activities in solution were determined as described. K_m values are for the substrates, glyceraldehyde 3-phosphate (GAP) for TPI and 3-phosphoglyceric acid (3-PGA) for GAPDHS.</p

Site-specific immobilization improved the coupled reaction of tethered enzymes.

<p>a) Forward TPI-GAPDHS coupled reaction. b) Reverse GAPDHS-TPI coupled reaction. Both enzymes were tethered via their His tags and site-specific immobilization (); both enzymes were tethered via carboxyl-amine binding (); control chips had no attached protein, but the complete reaction mixtures () [n = 9 (a), n = 12 (b); mean values are plotted with SE]. c) Comparison of forward TPI-GAPDHS activities at the 50 min timepoint calculated from (a). d) Comparison of reverse GAPDHS-TPI activities at the 60 min timepoint calculated from (b). Site-specific immobilization of His-NiNTA showed significantly higher activity (*p = 0.0001 ** p<0.001).</p

Site-specific immobilization improved specific activities of tethered enzymes.

<p>For both TPI and GAPDHS, site-specific immobilization using the His tag significantly improved enzyme specific activities versus carboxyl-amine binding. Although the total amounts of TPI (a) and GAPDHS (c) immobilized to carboxyl (C-A) or Ni-NTA activated surfaces were statistically identical, the specific activity of His-TPI bound to Ni-NTA was significantly higher than when bound via carboxyl-amine attachments (b; *p = 0.0143, n = 9). Similarly, the specific activity of His-GAPDHS was higher when bound to Ni-NTA versus carboxyl-amine binding (d; **p = 0.0234, n = 7).</p

Additional file 1 of Mackinawite nanozymes as reactive oxygen species scavengers for acute kidney injury alleviation

Additional file 1: Figure S1. The release trend of hydrogen polysulfide from GFeSNs. Figure S2. Iron ions released from different concentrations of GFeSNs in PBS solution. Figure S3. AFM image of GFeSNs and the corresponding height analysis. Figure S4. •OH scavenging ratio of the GFeSNs. Figure S5. O2•− scavenging efficiency and •OH scavenging ratio of GSH. Figure S6. O2•− scavenging efficiency of GFeSNs after 24 h and 48 h in PBS. Figure S7. CAT-like activity of GFeSNs. Figure S8. Different enzyme-like activity of GFeSNs under different pH conditions. Figure S9. SEM of GFeSNs after dispersed in distilled water for 24 h, 48 h, and 96 h, respectively. Figure S10. In vitro hemolysis test of GFeSNs. Figure S11. In vivo toxicity evaluation of GFeSNs to major organs (heart, liver, spleen, lung, and kidney) 7 days and 30 days after intravenous administration. Figure S12. Serum biochemistry assay and complete blood panel data of mice intravenously injected with PBS or GFeSNs at 24 h