Stealth Biocompatible Si-Based Nanoparticles for Biomedical Applications

Overcoming Cytosolic Delivery Barriers of Proteins Using Denatured Protein-Conjugated Mesoporous Silica Nanoparticles

Intracellular delivery of therapeutic proteins has increased advantages over current small-molecule drugs and gene therapies, especially in therapeutic efficacies for a broad spectrum of diseases. Hence, developing the protein therapeutics approach provides a needed alternative. Here, we designed a mesoporous silica nanoparticle (MSN)-mediated protein delivery approach and demonstrated effective intracellular delivery of the denatured superoxide dismutase (SOD) protein, overcoming the delivery challenges and achieving higher enzymatic activity than native SOD-conjugated MSNs. The denatured SOD-conjugated MSN delivery strategy provides benefits of reduced size and steric hindrance, increased protein flexibility without distorting its secondary structure, exposure of the cell-penetrating peptide transactivator of transcription for enhanced efficient delivery, and a change in the corona protein composition, enabling cytosolic delivery. After delivery, SOD displayed a specific activity around threefold higher than in our previous reports. Furthermore, the in vivo biosafety and therapeutic potential for neuron therapy were evaluated, demonstrating the biocompatibility and the effective antioxidant effect in Neuro-2a cells that protected neurite outgrowth from paraquat-induced reactive oxygen species attack. This study offers an opportunity to realize the druggable possibility of cytosolic proteins using MSNs.

Comparative study of the sensitivity of two freshwater gastropods, Lymnaea stagnalis and Planorbarius corneus, to silver nanoparticles: bioaccumulation and toxicity

Metal-based nanoparticles (NPs) are considered detrimental to aquatic organisms due to their potential accumulation. However, little is known about the mechanisms underlying these effects and their species-specificity. Here we used stable silver (Ag) NPs (20 nm, from 10 to 500 μg/L) with a low dissolution rate (≤2.4%) to study the bioaccumulation and biological impacts in two freshwater gastropods: Lymnaea stagnalis and Planorbarius corneus. No mortality was detected during the experiments. Ag bioaccumulation showed a dose-related increase with an enhanced concentration in both species after 7d exposure. L. stagnalis displayed a higher accumulation for AgNPs than P. corneus (e.g., up to 18- and 15-fold in hepatopancreas and hemolymph, respectively) which could be due to the more active L. stagnalis having greater contact with suspended AgNPs. Furthermore, the hepatopancreas and stomach were preferred organs for bioaccumulation compared to the kidney, mantle and foot. Regarding biological responses, the hemolymph rather than hepatopancreas appeared more susceptible to oxidative stress elicited by AgNPs, as shown by significantly increasing lipid peroxidation (i.e., formation of malondialdehyde). Neurotoxicity was detected in L. stagnalis when exposed to high concentrations (500 μg/L). Comparison with impacts elicited by dissolved Ag revealed that the effects observed on AgNPs exposure were mainly attributable to NPs. These results highlighted the relationship between the physiological traits, bioaccumulation, and toxicity responses of these two species to AgNPs and demonstrated the necessity of species-specificity considerations when assessing the toxicity of NPs.

Cationic Glycopolymers with Aggregation-Induced Emission for the Killing, Imaging, and Detection of Bacteria

Cationic glycopolymers with structures similar to those of typical poly(ionic liquid)s (PILs) were synthesized via the quaternization reaction of poly(4-vinyl pyridine) with halogen-functionalized d-mannose and tetraphenylethylene units. Such postpolymerization modification provided PILs with aggregation-induced emission effect as well as specific carbohydrate-protein recognition with lectins such as concanavalin A. The interactions between cationic glycopolymers and different microorganisms, including Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli, were used for the killing, imaging, and detection of bacteria. Besides, these sugar-containing PILs showed a relatively low hemolysis rate due to the presence of saccharide units, which may have potential application in the field of biomaterials.

Design of Engineered Cyclodextrin Derivatives for Spontaneous Coating of Highly Porous Metal-Organic Framework Nanoparticles in Aqueous Media

Nanosized metal-organic frameworks (nanoMOFs) MIL-100(Fe) are highly porous and biodegradable materials that have emerged as promising drug nanocarriers. A challenging issue concerns their surface functionalization in order to evade the immune system and to provide molecular recognition ability, so that they can be used for specific targeting. A convenient method for their coating with tetraethylene glycol, polyethylene glycol, and mannose residues is reported herein. The method consists of the organic solvent-free self-assembly on the nanoMOFs of building blocks based on β-cyclodextrin facially derivatized with the referred functional moieties, and multiple phosphate groups to anchor to the nanoparticles' surface. The coating of nanoMOFs with cyclodextrin phosphate without further functional groups led to a significant decrease of macrophage uptake, slightly improved by polyethylene glycol or mannose-containing cyclodextrin phosphate coating. More notably, nanoMOFs modified with tetraethylene glycol-containing cyclodextrin phosphate displayed the most efficient "stealth" effect. Mannose-coated nanoMOFs displayed a remarkably enhanced binding affinity towards a specific mannose receptor, such as Concanavalin A, due to the multivalent display of the monosaccharide, as well as reduced macrophage internalization. Coating with tetraethylente glycol of nanoMOFs after loading with doxorubicin is also described. Therefore, phosphorylated cyclodextrins offer a versatile platform to coat nanoMOFs in an organic solvent-free, one step manner, providing them with new biorecognition and/or "stealth" properties.