Construct a Magnetic Pt/Ru Alloy Peroxidase Mimic As a Reusable and Cost-Effective "Signal-Off" Sensing Platform for Sensitive and Wide-Linear-Range Assay.

"Signal-off" nanozyme sensing platforms are usually employed to detect analytes (e.g., ascorbic acid (AA) and alkaline phosphatase (ALP)), which are mostly based on oxidase (OXD) nanozymes. However, their drawbacks, like dissolved oxygen-dependent catalysis capability, relatively low enzyme activity, limited amount, and kind, may not favor sensing platforms' optimization. Meanwhile, with the need for sustainable development, a reusable "signal-off" sensing platform is essential for cutting down the cost of the assay, but it is rarely developed in previous studies. Magnetic peroxidase (POD) nanozymes potentially make up the deficiencies and become reusable and better "signal-off" sensing platforms. As a proof of concept, we first construct Fe3O4@polydopamine-supported Pt/Ru alloy nanoparticles (IOP@Pt/Ru) without stabilizers. IOP@Pt/Ru shows high POD activity with Vmax of 83.24 × 10-8 M·s-1 for 3,3',5,5'-Tetramethylbenzidine (TMB) oxidation. Meanwhile, its oxidation rate for TMB is slower than the reduction of oxidized TMB by reducers, favorable for a more significant detection signal. On the other hand, IOP@Pt/Ru possesses great magnet-responsive capability, making itself be recycled and reused for at least 15-round catalysis. When applying IOP@Pt/Ru for AA (ALP) detection, it performs better detectable adaptability, with a linear range of 0.01-0.2 mM (0.1-100 U/L) and a limit of detection of 0.01 mM (0.05 U/L), superior to most of OXD nanozyme-based ALP sensing platform. Finally, IOP@Pt/Ru's reusable assay was demonstrated in real blood samples for ALP assay, which has never been explored in previous studies. Overall, this study develops a reusable "signal-off" nanozyme sensing platform with superior assay capabilities than traditional OXD nanozymes, paves a new way to optimize nanozyme-based "signal-off" sensing platforms, and provides an idea for constructing inexpensive and sustainable sensing platforms.

A Cascade Enzyme System Integrating Peroxidase Mimic with Catalase for Linear Range Expansion of H2 O2 Assay: A Mechanism and Application Study.

Peroxidase (POD) Nanozyme-based hydrogen peroxide (H2 O2 ) detection is popular, but hardly adapt to high concentration of H2 O2 owing to narrow linear range (LR) and low LR maximum. Here, a solution of combining POD and catalase (CAT) is raised to expand the LR of H2 O2 assay via decomposing part of H2 O2 . As a proof of concept, a cascade enzyme system (rGRC) is constructed by integrating ruthenium nanoparticles (RuNPs), CAT and graphene together. The rGRC-based sensor does perform an expanded LR and higher LR maximum for H2 O2 detection. Meanwhile, it is confirmed that LR expansion is closely associated with apparent Km of rGRC, which is determined by the relative enzyme activity between CAT and POD both in theory and in experiment. At last, rGRC is successfully used to detect high concentration of H2 O2 (up to 10 mm) in contact lens care solution, which performs higher assay accuracy (close to 100% recovery at 10 mm of H2 O2 ) than traditional POD nanozymes. This study brings up a kind of POD/CAT cascade enzyme system and provides a new concept for accurate and facile H2 O2 detection. Additionally, it replenishes a new enzyme-substrate model of achieving the same pattern with competitive inhibition in enzyme reactions.

A Multiresponsive Nanohybrid to Enhance the Lysosomal Delivery of Oxygen and Photosensitizers.

Photodynamic therapy (PDT) is a promising cancer ablation method, but its efficiency is easily affected by several factors, such as the insufficient delivery of photosensitizers, low oxygen levels as well as long distance between singlet oxygen and intended organelles. A multifunctional nanohybrid, named MGAB, consisting of gelatin-coated manganese dioxide and albumin-coated gold nanoclusters, was designed to overcome these issues by improving chlorin e6 (Ce6) delivery and stimulating oxygen production in lysosomes. MGAB were quickly degraded in a high hydrogen peroxide, high protease activity, and low pH microenvironment, which is closely associated with tumor growth. The Ce6-loaded MGAB were picked up by tumor cells through endocytosis, degraded within the lysosomes, and released oxygen and photosensitizers. Upon near-infrared light irradiation, the close proximity of oxygen with photosensitizer within lysosomes enabled the production of cytotoxic singlet oxygen, resulting in more effective PDT.

Solvent effect on FRET spectroscopic ruler.

A discrepancy has emerged in recent years between single-molecule Förster resonance energy transfer (smFRET) measurements and small angle X-ray scattering (SAXS) or small angle neutron scattering experiments in the study of unfolded or intrinsically disordered proteins in denaturing solutions. Despite significant advances that have been made in identifying various factors which may have contributed to the manifestation of the so-called smFRET-SAXS discrepancy, no consensus has been reached so far on its original source or eventual resolution. In this study, we investigate this problem from the perspective of the solvent effect on FRET spectroscopic ruler (SEFSR), a generic term we use to describe various solvent-dependent factors affecting the accuracy of the FRET experimental method that is known as a "spectroscopic ruler." Some factors belonging to SEFSR, such as direct dye-solvent interaction and labeling configuration, seem to have not received due attention regarding their significance in contributing to the discrepancy. We identify SEFSR by measuring a rigid segment of a double-stranded DNA in various solutions using the smFRET method and evaluate its relative importance in smFRET experiments by measuring segments of a single-stranded DNA and polyethylene glycol (PEG) in solutions. We find that SEFSR can produce non-negligible FRET-inferred interdye distance changes in various solutions, with an intensity following the Hofmeister series in ionic solutions and dependent on labeling configurations. SEFSR is found to be significant in GuHCl and urea solutions, which can fully cover the apparent expansion signal of dye-labeled PEG. Our findings suggest that SEFSR may have played an important role in contributing to the smFRET-SAXS discrepancy.

Cooperative Strategies for Enhancing Performance of Photothermal Therapy (PTT) Agent: Optimizing Its Photothermal Conversion and Cell Internalization Ability.

Photothermal conversion ability (PCA) and cell internalization ability (CIA) are two key factors for determining the performance of photothermal agents. The previous studies mostly focus on improving the PCA by exploring new photothermal nanomaterials. Herein, the authors take the hybrids of graphene and gold nanostar (GGN) as an example to investigate the gradually enhanced phototherapy effect by changing the PCA and CIA of photothermal therapy (PTT) agent simultaneously. Based on the GGN, the GGN and the reduced GGN protected by bovine serum albumin (BSA) or BSA-FA (folic acid) are prepared, which are named as GGNB, rGGNB, and rGGNB-FA, respectively. The rGGNB showed an enhanced PCA compared to GGNB, leading to strong cell ablation. On the other hand, the 1,2-dioleoyl-3-trimethylammoniumpropan (DOTAP) can activate the endocytosis and promote the CIA of rGGNB, further help rGGNB to be more internalized into the cells. Finally, rGGNB-FA with the target ability can make itself further internalized into the cells with the aid of DOTAP, which can significantly destroy the cancer cells even at the low laser density of 0.3 W cm-2 . Therefore, a new angle of view is brought out for researching the PTT agents of high performance.

Anionic Lipid, pH-Sensitive Liposome-Gold Nanoparticle Hybrids for Gene Delivery - Quantitative Research of the Mechanism.

Gene therapy is a potential method for treating a large range of diseases. Gene vectors are widely used in gene therapy for promoting the gene delivery efficiency to the target cells. Here, gold nanoparticles (AuNPs) coated with dimethyldioctadecylammonium bromide (DODAB)/dioleoylphosphatidylethanolamine (DOPE) are synthesized using a facile method for a new gene vector (DODAB/DOPE-AuNPs), which possess 3- and 1.5-fold higher transfection efficiency than those of DODAB-AuNPs and a commercial transfection agent, respectively. Meanwhile, it is nontoxic with concentrations required for effective gene delivery. Imaging and quantification studies of cellular uptake reveal that DOPE increases gene copies in cells, which may be attributed to the smaller size of AuNPs/DNA complexes. The dissociation efficiency of DNA from the endocytic pathway is quantified by incubating with different buffers and investigated directly in the cells. The results suggest that DOPE increases the internalization of AuNPs/DNA complexes and promotes DNA release from early endosomes for the vector is sensitive to the anionic lipid membrane and the decreasing pH along the endocytic pathway. The new vector contains the potential to be the new alternative as gene delivery vector for biomedical applications.

Engineering injectable hyaluronic acid-based adhesive hydrogels with anchored PRP to pattern the micro-environment to accelerate diabetic wound healing.

Diabetic wounds remain a global challenge due to disordered wound healing led by inflammation, infection, oxidative stress, and delayed proliferation. Therefore, an ideal wound dressing for diabetic wounds not only needs tissue adhesiveness, injectability, and self-healing properties but also needs a full regulation of the microenvironment. In this work, adhesive wound dressings (HA-DA/PRP) with injectability were fabricated by combining platelet rich plasma (PRP) and dopamine-modified-hyaluronic acid (HA-DA). The engineered wound dressings exhibited tissue adhesiveness, rapid self-healing, and shape adaptability, thereby enhancing stability and adaptability to irregular wounds. The in vitro experiments demonstrated that HA-DA/PRP adhesives significantly promoted fibroblast proliferation and migration, attributed to the loaded PRP. The adhesives showed antibacterial properties against both gram-positive and negative bacteria. Moreover, in vitro experiments confirmed that HA-DA/PRP adhesives effectively mitigated oxidative stress and inflammation. Finally, HA-DA/PRP accelerated the healing of diabetic wounds by inhibiting bacterial growth, promoting granulation tissue regeneration, accelerating neovascularization, facilitating collagen deposition, and modulating inflammation through inducing M1 to M2 polarization, in an in vivo model of infected diabetic wounds. Overall, HA-DA/PRP adhesives with the ability to comprehensively regulate the microenvironment in diabetic wounds may provide a novel approach to expedite the diabetic wounds healing in clinic.

Succinic Ester-Based Shape Memory Gelatin Sponge for Noncompressible Hemorrhage without Hindering Tissue Regeneration.

Shape memory sponges are very promising in stopping the bleeding from noncompressible and narrow entrance wounds. However, few shape memory sponges have fast degradable properties in order to not hinder tissue healing. In this work, based on cryopolymerization, a succinic ester-based sponge (Ssponge) is fabricated using gelatin and bi-polyethylene glycol-succinimidyl succinate (Bi-PEG-SS). Compared with the commercially available gelatin sponge (Csponge), Ssponge possesses better water/blood absorption ability and higher mechanical pressure over the surrounding tissues. Moreover, in the models of massive liver hemorrhage after transection and noncompressive liver wounds by penetration, Ssponge exhibits a better hemostasis performance than Csponge. Furthermore, in a liver regeneration model, Ssponge-treated livers shows higher regeneration speed compared with Csponge, including a lower injury score, more cavity-like tissues, less fibrosis and enhanced tissue regeneration. Overall, it is shown that Ssponge, with a fast degradation behavior, is not only highly efficient in stopping bleeding but also not detrimental for tissue healing, possessing promising clinical translational potential.

A Hybrid Nanogel to Preserve Lysosome Integrity for Fluorescence Imaging.

Fluorescence imaging of lysosomes provides a powerful tool to probe the lysosome physiology in living cells, yet the continuous light exposure inevitably causes lysosome damage and phototoxicity, which remains a formidable challenge. Here the long-term lysosome tracking with minimized photodamage was realized using a multifunctional nanoprobe, a platinum nanoparticle, and a quinacrine co-loaded nanogel. To construct the hybrid nanogel, cisplatin first functioned as cross-linker to withhold all components and then was reduced to a platinum nanoparticle in situ by ethanol. The platinum nanoparticle enabled a long-term quinacrine fluorescence imaging of lysosome by scavenging the light induced reactive oxygen species which could damage lysosomal membranes.

Enzyme-Assisted Photodynamic Therapy Based on Nanomaterials.

Photodynamic therapy (PDT) is a noninvasive cancer treatment that requires the copresence of a photosensitizer (PS), oxygen, and light. The efficacy of conventional PDT is usually limited by two factors: delivery of the PS to the tumor and the hypoxic solid tumor environment. To improve the efficacy of PDT, nanomaterial-based, enzyme-assisted PDT (nano-ezPDT), which integrates enzyme-responsive components into nanomedicines, was developed for enhanced PS delivery and oxygen generation. Nano-ezPDT is designed to take full advantage of the catalytic function of locally activated tumor-associated enzymes or smuggled exogeneous enzymes. The enhancement of PS release and accumulation is often controlled by endogenous enzymes upregulated at the tumor sites. Oxygen generation, however, relies mostly on catalase-loaded nanomedicines. In this review, we discuss the associated enzymes, constructs, and types of nanocarriers and highlight the principle and utility of nano-ezPDT for cancer therapy.

Layer-by-layer construction of an oxygen-generating photo-responsive nanomedicine for enhanced photothermal and photodynamic combination therapy.

A multifunctional photosensitive and photothermal nanomedicine, AMP-Ce6-HA, was prepared by sequentially layering hard and soft functional molecules. AMP-Ce6-HA was efficiently picked up by MDA-MB-231 breast cancer cells, and then released oxygen in lysosomes. The photothermal and oxygen-enhanced photodynamic combination therapy was much more effective than the single one.

Construction of surface charge-controlled reduced graphene oxide-loaded Fe3O4 and Pt nanohybrid for peroxidase mimic with enhanced catalytic activity.

Hybrid nanomaterials with synergistic effect are highly potential for developing advanced nanozymes. Herein, we designed a nanozyme assembled by polyethylenimine (PEI)-protected reduced graphene oxide anchoring iron oxide (PRGI) and Pt nanoparticle using electrostatic interaction, PRGI/Pt nanohybrid. The different ratio of PRGI nanocomposite and Pt nanoparticle could control PRGI/Pt nanohybrid's surface charge and stability, which determined PRGI/Pt nanohybrid's catalytic activity. At the mass ratio of 0.8, the as-obtained PRGI/Pt nanohybrid showed the highest catalytic ability, and was better than Pt nanoparticle at different pH and temperature, although the PRGI/Pt nanohybrid showed lower affinity for TMB than Pt nanoparticle, which maybe attributed to the fact that PRGI/Pt nanohybrid possessed better product desorption ability or larger contact area. Furthermore, PRGI/Pt nanohybrid showed much higher catalytic activity than the sum of PRGI nanocomposite and Pt nanoparticle, indicating the strong cooperation between PRGI nanocomposite and Pt nanoparticle. Our study also provided a new way to conveniently construct nanozyme based on hybrid nanomaterials.

Investigation of an eco-friendly aerogel as a substrate for the immobilization of MoS2 nanoflowers for removal of mercury species from aqueous solutions.

An adsorbent that exhibits high affinity for inorganic mercury (Hg2+) with a high removal efficiency of methylmercury (MeHg+) has been developed. The adsorbent demonstrates a symbiotic relationship between its two components, molybdenum disulphide nanoflowers (MoS2NFs) and a poly (vinyl alcohol) (PVA) aerogel. Furthermore, we modified the distribution and loading of the MoS2NFs, which was possible due to the stable porous support, and investigated the biocompatibility of the aerogel-support adsorbent. The performance of the optimized material exhibited a distribution coefficient of 9.71 × 107 mL g-1. In addition, the adsorbent was effective over a wide pH range and could efficiently purify both contaminated lake and sea water. The key motivation for using an aerogel support was to stabilise the MoS2NFs during purification of the water (resulting in improved performance compared to using freestanding MoS2NFs) and the ability to regenerate the used adsorbent. In addition, animal tests confirmed an extremely low toxicity of the adsorbent to fish, along with the excellent purification results.

Designing metal-contained enzyme mimics for prodrug activation.

Enzyme-activated prodrug therapy (EAPT) is a widely-used and effective treatment method for cancer by converting prodrugs into drugs at the demanded time and space, whose key step is prodrug activation. Traditional prodrug activations are mostly dependent on natural enzymes, which are unstable, expensive and hard to be functionalized. The emerging enzyme mimics, especially the metal-contained enzyme mimics (MEMs), provide a potential chance for improving the traditional EAPT because of their high stability, low cost and easiness of preparation and functionalization. The existing MEMs can be classified into three categories: catalytic core-scaffold MEM (csMEM), nanoparticle MEM (npMEMs) and metal-organic framework (MOF) MEM (mofMEM). These MEMs can mimic diverse functions corresponding to natural enzymes, and some of which are potentially used in prodrug activation, such as DNase, RNase, carbonate esterase, etc. In this review, we briefly summarize the MEMs according to their structure and composition, and highlight the successful and potential applications for prodrug activation mediated by hydrolase-like and oxidoreductase-like MEMs.

Lipid-Coated Gold Nanoparticles Functionalized by Folic Acid as Gene Vectors for Targeted Gene Delivery in†vitro and in†vivo.

Lipid-based nanoparticles as gene vectors have attracted considerable attention for their high gene transfection efficiency and low cytotoxicity. In our previous work, we synthesized gold nanoparticles/dimethyldioctadecylammonium bromide (DODAB)/dioleoylphosphatidylethanolamine (DOPE) (GDD) as anionic lipid- and pH-sensitive gene vectors. To further realize targeted gene transfection, a series of gold nanoparticles/DODAB/DOPE/DOPE-folic acid (DOPE-FA) with various ratios of DOPE-FA were prepared and termed as GFn (for which n=1.0, 2.5, 5.0, 7.5, or 10.0 %). The gene transfection efficiency mediated by GF2.5 can reach about 85 % for MCF-7 (FA-receptor-positive cells), higher than those of the negative control (GDD, 35 %) and positive control (Lipofectamine 2000, 65 %). However, GF2.5 does not further promote gene transfection into A549 (FA-receptor-negative cells). The higher gene transfection efficiency for MCF-7 cells can be attributed to enhanced cellular uptake efficiency mediated by the FA targeting ability. Furthermore, GF2.5 was also found to accumulate at the specific tumor site and showed enhanced in vivo gene delivery ability. In addition, no significant harm was observed for the main tissues of the mice after treatment with GF2.5. Therefore, GF2.5, with the targeting ability and improved transfection efficiency, shows promise for its utility in gene therapy for tumor cells that overexpress FA receptors. We believe the results of this study will find more broad applications in gene therapy.

Hybrid of gold nanostar and indocyanine green for targeted imaging-guided diagnosis and phototherapy using low-density laser irradiation.

Phototherapy is widely studied with the development of photothermal nanomaterials. However, the laser power density for reaching effective phototherapy is still high and dangerous for normal tissues. In this research, based on multi-functional polydopamine, we proposed a general strategy to design diverse core-shell nanoparticles with different surface charges, and synthesized a targeted nanoplatform, AuNS@PDA-PEI-FA (APP), by coupling gold nanostar (AuNS) with polyethylenimine-folate (PEI-FA). Owing to the electrostatic interaction, the as-prepared APP can anchor a negatively-charged photosensitizer, indocyanine green (ICG), for photothermal and photodynamic synergistic cancer therapy. The APP-ICG is able to realize the targeted phototherapy for tumor cells even at the low power laser density of 0.33 W cm-2 both in vitro and in vivo. Furthermore, APP-ICG is not only a treatment nanoplatform but also a diagnosis agent. The integrative diagnosis results can be acquired by dual imaging technologies: the near-infrared fluorescence images and the photothermal images acquired by an in vivo imaging system and a thermal imaging camera, respectively. This new nanoplatform is a good diagnosis and treatment system and has the potential for further theranostics application.