Protein molecules were directly embedded in metal–organic frameworks (MOFs) by a coprecipitation method. The protein molecules majorly embedded on the surface region of MOFs display high biological activities. As a demonstration of the power of such materials, the resulting Cyt c embedded in ZIF-8 showed a 10-fold increase in peroxidase activity compared to free Cyt c in solution and thus gave convenient, fast, and highly sensitive detection of trace amounts of explosive organic peroxides in solution.

One-Pot Synthesis of Protein-Embedded Metal–Organic Frameworks with Enhanced Biological Activities

Bifunctionalized mesoporous silica-supported gold nanoparticles as oxidase and peroxidase mimics for antibacterial applications are demonstrated. For the first time, these mesoporous silica-supported gold nanoparticles are applied as oxidase and peroxidase mimics. Taking advantage of their prominent enzyme activities, the MSN-AuNPs show excellent antibacterial properties against both Gram-negative and Gram-positive bacteria. Furthermore, MSN-AuNPs also exhibit outstanding performance in biofilm elimination .

Bifunctionalized mesoporous silica-supported gold nanoparticles: intrinsic oxidase and peroxidase catalytic activities for antibacterial applications.

Biocatalytic transformations in cells, such as enzyme cascades, involve complex networks proceeding in spatially confined microenvironments. Here, inspired by nature, we demonstrate effective biocatalytic cascades by the encapsulation of two or three enzymes, or enzyme/cofactor components, in zeolitic imidazolate framework-8 metal–organic framework nanoparticles (ZIF8-NMOFs) that act as nanoreactors. The integration of the two-enzyme system (glucose oxidase and horseradish peroxidase) or three-enzyme system (β-galactosidase, glucose oxidase and horseradish peroxidase) in the NMOFs leads to 7.5-fold and 5.3-fold enhancements in the activity of the catalytic cascades, respectively, compared with the bulk mixture of the catalysts in solution. In addition, the encapsulation of alcohol dehydrogenase, NAD+–polymer and lactate dehydrogenase in the NMOFs yields a coupled biocatalytic cascade involving coupled NAD+-dependent enzymes, leading to the catalytic reduction of pyruvic acid to lactic acid by ethanol. High activity and stability of enzyme cascades are key to their biotechnological application. Here, Willner and co-workers demonstrate that encapsulation in metal–organic framework nanoparticles can improve these features for two- and three-enzyme, as well as NAD+-dependent, cascades.

Biocatalytic cascades driven by enzymes encapsulated in metal–organic framework nanoparticles

Reactive oxygen species (ROS)-induced apoptosis is a promising treatment strategy for malignant neoplasms. However, current systems are highly dependent on oxygen status and/or external stimuli to generate ROS, which greatly limit their therapeutic efficacy particularly in hypoxic tumors. Herein, we develop a biomimetic nanoflower based on self-assembly of nanozymes that can catalyze a cascade of intracellular biochemical reactions to produce ROS in both normoxic and hypoxic conditions without any external stimuli. In our formulation, PtCo nanoparticles are firstly synthesized and used to direct the growth of MnO2. By adjusting the ratio of reactants, highly-ordered MnO2@PtCo nanoflowers with excellent catalytic efficiency are obtained, where PtCo behaves as oxidase mimic and MnO2 functions as catalase mimic. In this way, the well-defined MnO2@PtCo nanoflowers not only can relieve hypoxic condition but also induce cell apoptosis significantly through ROS-mediated mechanism, thereby resulting in remarkable and specific inhibition of tumor growth.

/pdf/biomimetic-nanoflowers-by-self-assembly-of-nanozymes-to-56rvbgsmvm.pdf

Biomimetic nanoflowers by self-assembly of nanozymes to induce intracellular oxidative damage against hypoxic tumors.

Proteins are ideal building blocks for self-assembly of artificial cell-like architectures, but their realization is rare. Huang et al. report an interfacial assembly of protein–polymer conjugates, which exhibit cellular properties such as encapsulating guest molecules and switching enzyme activity.

/pdf/interfacial-assembly-of-protein-polymer-nano-conjugates-into-2vmzbq2tsh.pdf

Interfacial assembly of protein–polymer nano-conjugates into stimulus-responsive biomimetic protocells

Flower-shaped inorganic nanocrystals(1-3) have been used for applications in catalysis(4,5) and analytical science(6,7), but so far there have been no reports of 'nanoflowers' made of organic components(8). Here, we report a method for creating hybrid organic-inorganic nanoflowers using copper (II) ions as the inorganic component and various proteins as the organic component. The protein molecules form complexes with the copper ions, and these complexes become nucleation sites for primary crystals of copper phosphate. Interaction between the protein and copper ions then leads to the growth of micrometre-sized particles that have nanoscale features and that are shaped like flower petals. When an enzyme is used as the protein component of the hybrid nanoflower, it exhibits enhanced enzymatic activity and stability compared with the free enzyme. This is attributed to the high surface area and confinement of the enzymes in the nanoflowers.

/pdf/protein-inorganic-hybrid-nanoflowers-4v9xuuz5ir.pdf

Protein-inorganic hybrid nanoflowers

Amphiphilic bovine serum albumin-poly(methyl methacrylate) conjugate forms nanoparticles with the uniform size of ~100 nm by self-assembling. Loaded with the hydrophobic anti-tumor drug camptothecin, the nanoparticle efficiently delivers drugs into cancer cells, and thus inhibits ~79% of tumor growth in animals compared with free drug.

/pdf/protein-polymer-hybrid-nanoparticles-for-drug-delivery-45piop3kgk.pdf

Protein-polymer hybrid nanoparticles for drug delivery.

A new protein-polymer conjugate made of denatured bovine serum albumin (BSA) covalently bonded to poly(methyl methacrylate) (PMMA) is synthesized by attaching PMMA to acryloylated BSA followed by nanoparticle precipitation. Depending on the BSA to PMMA ratio, these conjugates self-assemble into uniform spherical nanoparticles which show "island" growth on the surface of the nanoparticles. This growth is promoted or retarded by exposing the nanoparticles to different solvents, causing the two components to undergo incipient phase separation. Incipient phase separation of the BSA-PMMA conjugate two-component system was observed in single nanoparticles, resulting in "island" growth on the surface of the nanoparticles. Incipient phase separation of the BSA-PMMA conjugate two-component system was observed in single nanoparticles, resulting in "island" growth on the surface of the nanoparticles.

/pdf/bovine-serum-albumin-poly-methyl-methacrylate-nanoparticles-3vplg620q4.pdf

Jiandu Lei

Papers

Protein-inorganic hybrid nanoflowers

Protein-polymer hybrid nanoparticles for drug delivery.

Bovine serum albumin-poly(methyl methacrylate) nanoparticles: an example of frustrated phase separation.