Surface design for high ion flux separator in lithium-sulfur batteries

Addressing the shuttle effect is a critical challenge in realizing practical applications of lithium-sulfur batteries. One promising avenue refers to the surface modification of separators, transitioning them from closed to open structures. In the current investigation, a high ion flux separator was devised by means of MnO2 self-assembly onto a Porous Polypropylene (PP) separator, subsequently coupling it with biochar. The separator exhibited favorable ion and electronic conductivity. Moreover, it adeptly captured and transformed polysulfides into Li2S2/Li2S, cyclically curbing the mobility of Polysulfide lithium (LiPSs). In addition, this augmentation in the kinetic conversion of LiPSs during the electrochemical process translated into an impressive discharge specific capacity and area capacity of 939 mAh/g and 4 mAh cm-2, respectively. Moreover, this innovative design methodology provides an alternative avenue for future separator designs within lithium-sulfur batteries.

Controllable ingestion and release of guest components driven by interfacial molecular orientation of host liquid crystal droplets

Controllable construction and manipulation of artificial multi-compartmental structures are crucial in understanding and imitating smart molecular elements such as biological cells and on-demand delivery systems. Here, we report a liquid crystal droplet (LCD) based three-dimensional system for controllable and reversible ingestion and release of guest aqueous droplets (GADs). Induced by interfacial thermodynamic fluctuation and internal topological defect, microscale LCDs with perpendicular anchoring condition at the interface would spontaneously ingest external components from the surroundings and transform them as radially assembled tiny GADs inside LCDs. Landau-de Gennes free-energy model is applied to describe and explain the assembly dynamics and morphologies of these tiny GADs, which presents a good agreement with experimental observations. Furthermore, the release of these ingested GADs can be actively triggered by changing the anchoring conditions at the interface of LCDs. Since those ingestion and release processes are controllable and happen very gently at room temperature and neutral pH environment without extra energy input, these microscale LCDs are very prospective to provide a unique and viable route for constructing hierarchical 3D structures with tunable components and compartments.

A gel-forming α-MSH analog promotes lasting melanogenesis

The α-MSH peptide plays a significant role in the regulation of pigmentation via the melanocortin 1 receptor (MC1R). It increases the DNA repair capacity of melanocytes and reduces the incidence of skin cancers. As such, α-MSH analogs could have the utility for protecting against UV-induced skin DNA damage in susceptible patients. Recently, α-MSH analogs have been approved for the treatment of erythropoietic protoporphyria, hypoactive sexual desire, or pediatric obesity. However, the delivery of these drugs requires inconvenient implants or frequent injections. We recently found that select palmitoylated melanocortin analogs such as afamelanotide and adrenocorticotropin peptides self-assemble to form liquid gels in situ. To explore the utility of these novel analogs, we studied their pharmacological characteristics in vitro and in vivo. Acylated afamelanotide (DDE 313) and ACTH1-24 (DDE314) analogs form liquid gels at 6-20% and have a significantly increased viscosity at >2.5% compared to original analogs. Using the DDE313 analog as a prototype, we showed gel-formation reduces the passage of DDE313 through Centricon filters, and subcutaneous injection of analog gel in rats leads to the sustained presence of the peptide in circulation for >12 days. In addition, DDE313 darkened the skin of frogs for >4 weeks, whereas those injected with an equivalent dose of afamelanotide lost the tanning response within a few days. Because self-assembled gels allow sustained activation of melanocortin receptors, further studies of these analogs may allow the development of effective and convenient tanning therapies to prophylactically protect against UV-induced malignant transformation of skin cells in susceptible patients.

A novel self-assembled nanoplatform based on retrofitting poloxamer 188 for triple-negative breast cancer targeting treatment

Poloxamer 188 is a widely used pharmaceutical excipient, which can be found in a variety of drug formulations. In this study, a novel self-assembled nanoplatform was developed for active targeting of folate receptor-overexpressing triple-negative breast cancer. This platform, FPP NPs, was prepared by the retrofitted poloxamer 188 derivatives, resulting in nanoparticles with an appropriate size (< 100 nm), good stability, and satisfactory biocompatibility. Cellular uptake and in vivo distribution studies showed that the FPP NPs had strong tumor cell uptake and active targeting capabilities. Furthermore, docetaxel (DTX) was loaded into FPP NPs in this research. The resulting DTX/FPP NPs exhibited high drug encapsulation efficiency and drug loading capacity, and could rapidly release DTX under slightly acidic conditions, significantly increasing the antitumor activity of the encapsulated drug both in vitro and in vivo. In addition, DTX/FPP NPs could significantly decrease the hepatotoxicity and nephrotoxicity of DTX. Therefore, this drug delivery nanoplatform, based on retrofitted poloxamer 188 with self-assembly properties in aqueous solution and active targeting capabilities to tumors, may provide a promising approach for targeted treatment of triple-negative breast cancer.

Development of Au8 nanocluster-based fluorescent strip immunosensor for sensitive detection of aflatoxin B1

Gold clusters with intriguing chemical/physical properties have great promise in applications such as sensing and bio-imaging due to their fascinating photoluminescence character. In this study, an immunofluorescence sensor based on levonorgestrel protected atomically precise Au₈ nanocluster (Au₈NC) for aflatoxin B₁ (AFB₁) detection was fabricated due to its strong carcinogenic and mutagenic effect on humans. The prepared polymer-Au₈NC nanospheres displayed bright luminescence and good stability in aqueous solution. The obtained AFB₁ fluorescent strip immunosensor achieved quantitative point-of-care detection of AFB₁ in less than 15 min, with high selectivity and detection limits down to 0.27 ng/mL. In addition, the recovery rates of AFB₁ from tea soup ranged from 96% to 105% with relative standard deviations less than 10%. This work not only realized high-sensitively fluorescent sensing for AFB₁, but also expanded the bio-applications of atomic-precise metal clusters.

Built-up sodium alginate/chlorhexidine multilayer coating on dental implants with initiating anti-infection and cyto-compatibility sequentially for soft-tissue sealing

Soft-tissue sealing at transmucosal sites is very important for preventing the invasion of pathogens and maintaining the long-term stability and function of dental implants. However, the colonization of oral pathogens on the implant surface and surrounding soft tissues can disturb the early establishment of soft-tissue sealing and even induce peri-implant infection. The purpose of this study was to construct two antibacterial coatings with 5 or 10 sodium alginate/chlorhexidine bilayers on titanium surfaces using layer-by-layer self-assembly technology to promote soft-tissue sealing. The corresponding chemical composition, surface topography, wettability and release behaviour were investigated to prove that the resultant coating of sodium alginate and chlorhexidine was coated on the porous titanium surface. In-vitro and in-vivo antibacterial results showed that both prepared coatings inhibited or killed the bacteria on their surfaces and the surrounding areas to prevent plaque biofilm formation, especially the coating with 10 bilayers. Although both coatings inhibited the initial adhesion of fibroblasts, the cytocompatibility gradually improved with coating degradation. More importantly, both coatings achieved cell adhesion and proliferation in an in-vitro bacterial environment and effectively alleviated bacteria-induced subcutaneous inflammation in-vivo. Therefore, this study demonstrated that the multilayered coating could prevent implant-related infections in the initial stage of implant surgery and then improve soft-tissue integration with implant devices.

Nanotubes fabricated from a triple helix polysaccharide as a novel carrier delivering doxorubicin for breast cancer therapy

Most current strategies of drug delivery systems face momentous challenges owing to obvious biological barriers. It is urgently necessary to develop artificial nanocarriers with biological and physical properties to reduce the severe system cytotoxicity of chemical drugs. Herein, triggered by the stiffness and amphiphilicity of the triple helix β-glucan (LNT), we developed a novel nanocarrier with the hydrophobic cavity for delivering the anti-cancer drug of doxorubicin. In our findings, based on the law of minimum surface energy, LNT with considerable chain stiffness self-assembled into nanotubes (LNT-NT) with the controlled hydrophobic nanotube diameter at the nanometer level positively depending on the molecular weight through hydrogen bonding and hydrophobic interaction in manners of "shoulder-to-shoulder" and "head-to-head" arrangements. The hydrophobic drug of doxorubicin was then demonstrated to be entrapped into LNT-NT through hydrophobic interaction. Doxorubicin loaded into LNT-NT nanocarriers significantly inhibited tumor growth in vitro and in vivo by promoting tumor cell apoptosis and blocking cell proliferation, showing a higher therapeutic efficacy of 74.5 % and less adverse effects than the free doxorubicin, which was ascribed to the enhanced targetability by LNT-NT. In conclusion, this work proposes an alternative strategy for delivering hydrophobic drugs to reduce cytotoxicity and enhance therapeutic effectiveness by constructing β-glucan-based nanotubes as a promising nanocarrier.

Fabrication of flexible AuNPs@ polyimide heating chips for in situ explosives SERS sensing in nature samples

In this study, highly sensitive flexible AuNPs@ polyimide SERS heating chips (APHC) were fabricated for in situ collecting and detecting TNT. Large-scale AuNPs arrays were synthesized by liquid-liquid interface self-assembly and transferred to polyimide heating film as SERS substrates. 4-ATP and AgNPs functionalized on APHC were used as capture means and signal amplifiers, combining with TNT to form the AuNPs-TNT-AgNPs "sandwich" structure. This flexible APHC chip showed high sensitivity as enhancement factor was 5.5×10⁵, and good repeatability and stability (RSD<10%). It was applied to detect TNT solutions with a low concentration of 10^-9 M, and showed a good linear response in the range from 10^-5 to 10^-9 M (R² = 0.986). In addition, the detection method also had good selectivity and no response to various TNT analogs. More important, combing with the thermal enrichment strategy, TNT dispersed in environmental samples such as soil, fruit and clothing would be enriched as vapor then collected and detected by APHC. This APHC device shows great potential for in situ sensing platforms, due to its sensitivity, high efficiency, and excellent portability.

Thiolated chitosan nanoparticles for stable delivery and smart release of As2O3 for liver cancer through dual actions

In this work, multifunctional thiolated chitosan derivatives (DCA-CS-PEG-FA-NAC) were synthesized, and arsenic trioxide (ATO) was loaded onto the derivatives through glutathione (GSH)-sensitive As^III-S bonds, and stable CS-ATO nanodrugs were prepared by simple self-assembly method. By adjusting the thiol substitution degree of CS, the drug loading capacity of the nanodrugs was significantly improved, which could reach 20 ATO per CS molecule (DCA_10.7-CS-PEG_3.1-FA-NAC_20.2-ATO). In vitro release studies obviously showed the low leakage of ATO under physiological conditions while over 95 % ATO was released after 24 h under GSH. In vitro and in vivo investigations demonstrated that the DCA_10.7-CS-PEG_3.1-FA-NAC_20.2-ATO nanodrug could significantly enhance the tumor intracellular accumulation of ATO, reduce the toxic and side effects of ATO on healthy organs, and improve the therapeutic effect of ATO on the HepG2 mice tumor model (tumor inhibition rate was as high as 86.4 %), indicating the potential application of ATO in clinical treatment of liver cancer.

Rational design of pH-activated upconversion luminescent nanoprobes for bioimaging of tumor acidic microenvironment and the enhancement of photothermal therapy

The development of effective and safe tumor photothermal therapeutic strategies has attracted considerable attention. Herein, we synthesized tumor microenvironment (TME)-activatable self-assembling organic nanotheranostics (NRhD-PEG-X NPs (X = 1, 2, 3, and 4)) for precise tumor targeting and upconversion image-guided photothermal therapy (PTT). The amphiphilic polymer NRhD-PEG-X consisted of upconversion luminescent probes (NRhD) modified with polyethylene glycol (PEG) of various lengths. The continuous external irradiation-free photothermal NRhD-PEG-4 NPs with pKa 6.70 displayed high sensitivity and selectivity to protons, resulting in the turn-on upconversion luminescence and enhanced photothermal properties in the acidic TME without asynchronous therapy and side effects. This nanotheranostic offers acidic activatability, tumor targetability, and PTT enhancement, thus allowing autofluorescence-free upconversion luminescent imaging-guided precision PTT. Our strategy affords a paradigm to develop activatable theranostic nanoplatforms for precision medicine. STATEMENT OF SIGNIFICANCE: As a hyperthermia-based treatment, activatable photothermal therapy (PTT) is highly significant in tumor treatment. Herein, we develop acidic tumor microenvironment-activatable nanotheranostics for upconversion luminescent imaging-guided diagnosis and precision tumor-targeted PTT. PEGylation of upconversion dyes not only could self-assemble to yield organic nanoparticles in water, but it could also significantly improve biocompatibility, stability, and circulation time and tune significantly the pKa value of nanoparticles. In an acidic tumor microenvironment, NRhD-PEG-4 NPs with pKa 6.70 show high sensitivity to release NRhDH⁺-PEG-4 NPs, which exhibit good upconversion luminescence and enhanced photothermal effect. Therefore, upconversion luminescence imaging-guided precision PTT has high potential to enhance cancer diagnostic and therapeutic efficiency.

Tailoring the multi-functional properties of phospholipids for simple to complex self-assemblies

The unique interfacial properties, huge diversity, and biocompatible nature of phospholipids make them an attractive pharmaceutical excipient. The amphiphilic nature of these molecules offers them the property to self-assemble into distinct structures. The solubility, chemical and structural properties, surface charge, and critical packing parameters of phospholipids play an essential role during formulation design. This review focuses on the relationship between the structural features of a phospholipid molecule and the formation of different lipid-based nanocarrier drug delivery systems. This provides a rationale and guideline for the selection of appropriate phospholipids while designing a drug delivery system. Finally, we refer to relevant recent case studies covering different types of phospholipid-based systems including simple to complex assemblies. Different carriers in the size range of 50 nm to a few microns can be prepared using phospholipids. The carriers can be delivered through oral, intravenous, nasal, dermal, transmucosal, and subcutaneous routes. A wide range of applicability can be achieved by incorporating various hydrophilic and lipophilic additives in the phospholipid bilayer. Advanced research has led to the discovery of phospholipid complexes and cell membrane mimicking lipids. Overall, phospholipids remain a versatile pharmaceutical excipient for drug delivery. They play multiple roles as solubilizer, emulsifier, surfactant, permeation enhancer, coating agent, release modifier, and liposome former.

A novel self-assemble peptide drug design of AKT1 for anaplastic thyroid cancer therapy

Anaplastic thyroid cancer (ATC) is an undifferentiated subtype of thyroid cancer with a markedly poor survival prognosis, estimated to occur 3-5 months after diagnosis. Akt activation is reportedly involved in tumorigenesis during ATC and represents a new therapeutic target. Based on the Akt1/bisubstrate complex structure and artificial intelligence-assisted peptide drug screening, we designed a self-assemble Akt1-targeting peptide drug exhibiting a 0.89-nm structure and potential killing ability in ATC cells. The developed self-assemble Akt1-targeting peptide drug presented IC₅₀ values of 18.2 μM and 12.4 μM in 8303C and 8505C cells, respectively, after 72 h of incubation.

Two-dimensional colloidal crystal of soft microgel spheres: Development, preparation and applications

Two-dimensional (2D) colloidal crystals are ordered monolayer arrays of colloidal sphere particles assembled on the substrates or at phase interfaces. Owing to their unique periodic structure and fascinating properties, 2D colloidal crystals have aroused considerable interest because of their potential applications. Among them, 2D colloidal crystals self-assembled from soft microgel spheres stand out particularly. The 2D colloidal crystals of soft microgel spheres combine the advantages of monolayer colloidal crystals and sensitive microgels, which have a good application prospect in biomedical area. In this article, we provide a systematic overview of 2D colloidal crystals of soft microgel spheres related to their development, preparation and applications. First, various preparation methods of 2D colloidal crystal of microgels are introduced, including dip-coating, drop-coating, spin-coating, interface assembly, surface reaction-assisted assembly, and so forth. Second, representative biomedical applications consisting of optical sensor, drug delivery, antibacterial coating, cell culture, and colloidal template are also exemplified to show the high performance of 2D colloidal crystals of soft microgel spheres. In addition, we also present prospects of future developments of 2D microgel colloidal crystals.

Kinetically-stable small-molecule prodrug nanoassemblies for cancer chemotherapy

Self-delivering nanocarrier based on the small-molecule prodrug nanoassemblies (NAs) have been widely used for the efficient delivery of chemotherapeutics, but the effect of kinetic stability of NAs on their delivery performance has not been illuminated. In this study, two camptothecin (CPT)-oleic acid (OA) prodrugs were used to fabricate self-assembling nanorods with similar size distribution, zeta potential and morphology but having sharply different kinetic stability, which provided an ideal platform to investigate the effects of kinetic stability. It is found that the nanorods with high kinetic stability showed a lower in vitro cytotoxicity, but were more effective to inhibit the tumor growth probably by decreasing the premature CPT release and subsequent generation of the inactive carboxylate CPT. However, such kinetically stable nanorods also resulted in the increased toxicity, probably due to the high prodrug accumulation in tissues after multiple injections. These results outlined the pivotal role of kinetic stability in determining antitumor efficacy of prodrug NAs, which provided a new insight into the delivery mechanism for the small-molecule prodrug self-delivering nanosystems.

Dual-light triggered metabolizable nano-micelles for selective tumor-targeted photodynamic/hyperthermia therapy

Phototherapy, including photodynamic and photothermal therapies, is a non-invasive photo-triggered tumor treatment. Combination therapy and new synergistic therapeutic reagents may hold promise for improving these treatments. Herein, we report an amphiphilic iridium-based photosensitizer (C14-IP2000) loaded with a hydrophobic photo-thermal drug (ZnPc) to form nano-micelles (ZNPs) for dual-light triggered tumor phototherapy. The C14-IP2000 was contained within ZNPs consisting of an iridium complex core decorated with hydrophilic polyethylene glycol chains to extend the time in blood circulation, and two hydrophobic carbon chains to enhance the loading capacity and the hydrophobic interaction with the loaded reagent. The designed ZNPs showed effective blood circulation, passive tumor targeting ability, remarkable photodynamic conversion ability, and good photothermal conversion capability, and therefore may be used for combined tumor ablation. Our results demonstrated that the amphipathic bionic structure of ZNPs not only enables self-assembled reagent fabrication with prolonged circulation time and favorable metabolic characteristics for tumor combination therapy, but also provides a nanostructure strategy for the modification of functionalized reagents.

Three-dimensional ordered macroporous magnetic photonic crystal microspheres for enrichment and detection of mycotoxins (I): Droplet-based microfluidic self-assembly synthesis

Ordered porous materials are attracting enormous attention due to their uniform pore structures, particularly the magnetic photonic crystal microspheres (PCMs) which not only possess unique photonic crystal structure but also can achieve separation easily based on magnet. Here, a two-phase microfluidic self-assembly synthetic system was established simply and employed for the preparation of three dimensional PCMs (3DPCMs) by using the emulsion droplet approach. One phase (dispersed phase) was an aqueous emulsion containing Fe₃O₄, silica (SiO₂) and polystyrene (PS) nanoparticles; another phase (continuous phase) was pure silicone oil. The droplets were formed by introducing the dispersed phase into the continuous phase through a tee valve. By heating the droplets, the water would evaporate and the nanoparticles would finally assemble into solid microspheres, which could be changed into macroporous 3DPCMs after removal of the PS nanoparticles by calcination. The contents and particle sizes of Fe₃O₄, SiO₂ and PS nanoparticles in the dispersed phase were investigated in detail and optimized to prepare macroporous magnetic 3DPCMs with high quality. The morphologies, surface crystal structure, magnetic property, particle size distribution, specific surface area and pore size of the macroporous magnetic 3DPCMs were characterized. The expected 3DPCM displayed regular and uniform photonic crystal structure, narrow particle size distribution and strong magnetic property. The macroporous magnetic 3DPCMs grafted with vomitoxin (DON)-antibodies could be applied for selective enrichment of DON in real samples.

Fungal Hydrophobin RolA Enhanced PETase Hydrolysis of Polyethylene Terephthalate

Polyethylene terephthalate (PET) becomes one of the most well-known polyesters and is widely used as packaging material. Recently, polyethylene terephthalate hydrolase (PETase) has emerged as a potential biocatalyst demonstrating the ability to degrade polyethylene terephthalate (PET). We showed that the rate of PETase hydrolysis could be significantly increased in the presence of hydrophobin RolA. Hydrophobins represent a class of small fungal protein that has a high surface-active substance and can spontaneously self-assemble at hydrophilic-hydrophobic interfaces. In this work, a class I hydrophobin named RolA was extracted from the mycelium pellet collected from a fermentation culture of Aspergillus oryzae. The SDS-PAGE analysis of the isolated RolA showed the presence of 11 kDa polypeptide. Recombinant PETase from Ideonella sakaiensis was also successfully expressed in Escherichia coli as a soluble protein with molecular weight approximately 30 kDa. The hydrophobin RolA could enhance the PET hydrolysis in the presence of the recombinant PETase. The hydrolysis of PET bottle by RolA-PETase achieved the highest weight loss of 26% in 4 days. It is speculated that the wetting effect of RolA acts on PET surface converts PET to become hydrophilic that leads PETase easier to contact and attack the surface. Graphical Abstract.

Diversity of complexes based on p-nitrobenzoylhydrazide, benzoylformic acid and diorganotin halides or oxides self-assemble: Cytotoxicity, the induction of apoptosis in cancer cells and DNA-binding properties

Eight organotin(IV) complexes (C1-C8) have been synthesized and characterized by elemental analysis, fourier transform infrared spectroscopy (FT-IR), multinuclear nuclear magnetic resonance (¹H, ¹³C and ¹¹⁹Sn NMR), high resolution mass spectroscopy (HRMS) and single crystal X-ray structural analysis. Crystallographic data show that C1 was a tetranuclear 16-membered macrocycle complex, C2-C4 and C7 were centrosymmetric dimer distannoxane and there was a Sn₂O₂ four-membered ring in the middle of the molecule, respectively, C5 and C6 are monoorganotin complexes due to the dehydroalkylation effect during the reaction, while C8 forms a one-dimensional chain structure. The cytotoxicity of all complexes were tested by 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assays against three human tumor cell lines NCI-H460, MCF-7 and HepG2. The dibutyltin complex C2 has been shown to be more potent antitumor agents than other complexes and carboplatin. Cell apoptosis study of C2 with the high activity on HepG2 and MCF-7 cancer cell lines was investigated by flow cytometry, it was shown that the antitumor activity of C2 was related to apoptosis, but it has different cell cycle arrest characteristics from platinum compounds, and the proliferation was inhibited by blocking cells in S phase. The DNA binding activity of the C2 was studied by UV-visible absorption spectrometry, fluorescence competitive, viscosity measurements and gel electrophoresis, results shown C2 can be well embedded in the double helix of DNA and cleave DNA.

Acid-resistant enzyme@MOF nanocomposites with mesoporous silica shells for enzymatic applications in acidic environments

Zeolitic imidazole frameworks (ZIFs) with tunable pore sizes and high surface areas have recently used as an effective support for immobilizing enzymes. However, the instability in the aqueous acidic environment has limited their practical applications in some cases. In this work, we develop a novel catalase/ZIFs composite with mesoporous silica shell (mSiO₂@CAT/ZIFs) via co-precipitation, and controlled self-assembly of silanes. During preparation, the cetyltrimethylammonium bromide induced the formation of the mesostructured silica layer on the outer surface of CAT/ZIFs. The resultant mSiO₂@CAT/ZIFs exhibited high activity recovery (92%). Compared with the conventional CAT/ZIFs and free CAT, mSiO₂@CAT/ZIFs exhibited excellent acid resistance. For example, after 30 min in acetate buffer solution (pH 3.0), the CAT/ZIFs and free CAT almost lost activity whereas the mSiO₂@CAT/ZIFs still retained 35% of original activity. Meanwhile, the thermostability of the mSiO₂@CAT/ZIFs was enhanced significantly compared with conventional CAT/ZIFs. In addition, the mSiO₂@CAT/ZIFs displayed excellent storage stability, and retained 60% of its initial activity after 15 days storage period. Furthermore, the mSiO₂@CAT/ZIFs could maintain 70% of its initial activity after 8 continuous uses, demonstrating superior reusability than the free CAT and CAT/ZIFs. These results demonstrated that the mSiO₂@CAT/ZIFs are potential for practical applications even in the acidic environment.

Self-assembled fluorescent Ce(Ⅲ) coordination polymer as ratiometric probe for HIV antigen detection

The viral capsid protein p24 of human immunodeficiency virus is expressed at different level during viral invasion. Detection of p24 is of great importance in acquired immunodeficiency syndrome monitoring and therapy. A ratiometric probe that is easily-synthesized was constructed based on self-assembled fluorescent Ce(Ⅲ) and fluorescein. Fluorescein was used as reference. Hydrogen peroxide quenches the fluorescence of the Ce(III) easily but does not quench the fluorescence of fluorescein. The mechanism of reaction was discussed. Benefiting from the sensitive response to hydrogen peroxide, this probe was applied for p24 detection in enzyme linked immunoassay. The fluorescence ratio was in a good linear relationship with the concentration of p24, and the detection limit was 1.1 pg mL^-1. This proposed method has shown potential in virus detection with easy operation.

Interaction between human serum albumin and cholesterol-grafted polyglutamate as the potential carriers of protein drugs

Currently there is no successful platform technology for the sustained release of protein drugs. It seems inevitable to specifically develop new materials for such purpose, and hence the understanding of protein–material interactions is highly desirable. In this study, we synthesized cholesterol-grafted polyglutamate (PGA-g-Chol) as a hydrophobically-modified polypeptide, and thoroughly characterized its interaction with a model protein (human serum albumin) in the aqueous solution by using circular dichroism, fluorescence methods, and light scattering. With the protein concentration fixed at 5 μmol/L, adding PGA-g-Chol polymers into the solution resulted in continuous blue shift of the protein fluorescence (from 339 to 332 nm), until the polymer molar concentration reached the same value as the protein. In contrast, the un-modified polyglutamate polymers apparently neither affected the protein microenvironment nor formed aggregates. Based on the experimental data, we proposed a physical picture for such protein–polymer systems, where the polymer first bind with the protein in a 1:1 molar ratio via a fraction of their hydrophobic pendant cholesterol resides along the polymer chain. In this protein/polymer complex, there are excess unbound cholesterol residues. As the polymer concentration increases, the polymers form multi-polymer aggregates around 200 nm in diameter via the same hydrophobic cholesterol residues. The protein/polymer complex also participate in the aggregation via their excess cholesterol residues, and consequently the proteins are encapsulated into the nanoparticles. The encapsulation was also found to increase the thermal stability of the model protein.

Enhanced sulfate and metal removal by reduced graphene oxide self-assembled Enterococcus avium sulfate-reducing bacteria particles

Graphene oxide (GO) was introduced to Enterococcus avium strain BY7 sulfate-reducing bacteria culture as a carrier, GO was partially reduced by SRB to reduced graphene oxide (rGO). The rGO could further self-assemble Enterococcus avium strain BY7 sulfate-reducing bacteria to form BY-rGO particles. Growth and sulfate reduction activity of strain BY7 was promoted by rGO, which probably due to the protective effect of rGO, and enhanced electron transfer by rGO as electron shuttle. Effects of pH and temperature variance on strain BY-rGO were remarkably weakened, growth and sulfate reduction were observed from pH 2.0 to 12.0, and from 10 to 45 °C, respectively. Metal toxicity to BY7 strain SRB was sharply decreased in BY-rGO particles and heavy metal removal was remarkably accelerated (up to 50%). The immobilization methods established in this study might open a new way for the application of SRBs, especially under extreme environmental conditions.

Methotrexate-based amphiphilic prodrug nanoaggregates for co-administration of multiple therapeutics and synergistic cancer therapy

The goal of nanomedicine is to seek strategies that are more efficient to address various limitations and challenges faced by conventional medicines, including lack of target specificity, poor bioavailability, premature degradability, and undesired side effects. Self-assembling drug amphiphiles represent a prospective nanomedicine for cancer therapy owing to their favorable route of administration and therapeutic efficiency compared with pristine drug counterparts. In this work, we report a class of self-deliverable prodrug amphiphiles consisting of the hydrophilic drug methotrexate (MTX) and the hydrophobic anticancer drugs camptothecin (CPT) and doxorubicin (DOX) for targeted and combinational chemotherapy. The disulfide bond and hydrazone bond, which are subject to stimuli-triggered bond cleavage, were introduced to link these therapeutic agents and form two prodrug amphiphiles, named as MTX-CPT and MTX-DOX, respectively, which could self-assemble into stable prodrug nanoaggregates (NAs) in aqueous media. MTX molecules in the prodrug NAs facilitated NA uptake into tumor cells with high expression of folic acid receptors (FRs). This systemic study provided clear evidence of the synergistic therapeutic effect by co-administrating dual prodrug NAs on various tumor cells in vitro and a xenograft tumor model in vivo. The obtained prodrug amphiphiles provide an efficient strategy for the design of multifunctional drug delivery systems and elaborate therapeutic nanoplatforms for cancer chemotherapy.

STATEMENT OF SIGNIFICANCE

This work presents two kinds of prodrug amphiphiles that are carrier free and integrate targeted drug delivery, stimuli-triggered drug release, synergistic therapy, and theranostic function into a single system. Reduction/acid active prodrug amphiphiles can self-assemble into micellar nanoaggregates (NAs) at a very low critical aggregation concentration. These NAs exhibit superior stability in physiological environment and disassemble in the presence of tumor cells expressing folic acid receptors or the high glutathione or in low pH tumoral endosomal environment. The induced disassembly of prodrug NAs can "switch on" the inherent fluorescence of the internalized camptothecin or doxorubicin for the detection of tumor cells. Compared to a single type of prodrug NA, co-administration of dual prodrug combination can produce an evident synergistic therapeutic effect against various tumor cells in vitro and inhibit xenograft tumor growth in vivo. The methotrexate-based prodrug amphiphiles may provide a potential strategy for developing multifunctional nanoplatforms and delivery of multiple therapeutics in chemotherapy.

Construction and biological evaluation of different self-assembled nanoarchitectures of FZU-03,010

Chemotherapy is currently one of the promising therapeutic methods for non-small-cell lung cancer (NSCLC), but the emergence of multidrug resistance (MDR) is the greatest obstacle to efficient drug delivery for successful chemotherapy. Nanotechnology-based drug delivery holds great promise to promote intracellular drug delivery to reverse MDR. In this work, we used our previously synthesized ursolic acid (UA) derivative, FZU-03,010 (F3), to prepare nanodrugs of F3 with different architectures and study the role of the structure on the physiochemical properties and the biological effects against A549 and its PTX-resistant A549/PTX lung cancer cells. Using different preparation methods, amphiphilic F3 could self-assemble into different structures such as nanoaggregates (F3-NA), vesicles (F3-VC), or nanoparticles (F3-NP) with different physiochemical properties. The self-assembled nanodrugs could be utilized for the entrapment of fluorophores and showed different cellular uptake efficiencies. The cytotoxicity results demonstrated that compared with UA, F3-NA and F3-NP could suppress A549 and A549/PTX cells viability more potently at lower concentration. In addition, F3-NA and F3-NP could induce G1 cell cycle arrest, cell apoptosis and caspase-3 activation more efficiently than that of UA. Furthermore, F3-NA and F3-NP could effectively inhibit PI3K/Akt pathway and decrease the expression of Bcl-2 and the cell cycle-dependent kinase inhibitors p-ERK1/2 and Cyclin D1 in both A549 and A549/PTX cells. In conclusion, our results suggest that the UA derivative F3 is more potent in inhibiting cancer cell proliferation, and F3-NA and F3-NP have the potential to be developed as a therapeutic agent for resistant NSCLC cells.

A novel self-assembled nanoparticle platform based on pectin-eight-arm polyethylene glycol-drug conjugates for co-delivery of anticancer drugs

The application of non-toxic carriers to increase drug loading, multi-drug delivery, and extremely small size of nano-drugs to construct a tremendous transmission system is the goal for all researchers to be pursued. The proposal of natural pectin nano-platform for delivery of multiple drugs is critical for biomedical research, especially a particle size of below 100nm with high yield. Here we design a new core-shell structure pectin-eight-arm polyethylene glycol-ursolic acid/hydrooxycampothecin nanoparticle (Pec-8PUH NPs) through a special self-assembly method for stabilizing and dispersing particles, improving water-solubility, and achieving drug controlled release. The obtained Pec-8PUH NPs possessed appropriate size (~91nm), drug-loaded efficiency and encapsulation efficiency through the regulation of eight-arm polyethylene glycol. In addition, Pec-8PUH NPs could enhance cell cytotoxicity, shorten blood retention time (7.3-fold UA, 7.2-fold HCPT) and more effective cellular uptake than free drugs, which exhibited an obvious synergistic effect of UA and HCPT by the co-delivery. 4T1 tumor-bearing mice also showed a higher survival rate than free UA and free HCPT. The result further shows that this novel drug delivery system has a promising potential for anti-cancer combination therapy.

Design of diversified self-assembly systems based on a natural rosin-based tertiary amine for doxorubicin delivery and excellent emulsification

A novel rosin-based ester tertiary amine (RETA) with three hydrophilic groups and a rigid hydrophobic group was synthesized from rosin by Diels-Alder addition, acylation and esterification reactions. RETA was characterized by infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy (¹³C NMR). Results from testing surface tension, zeta potential, and transmission electron spectroscopy showed that RETA had unique pH responsiveness. RETA self-assembled into worm-like micelles, spherical micelles 130 nm in diameter and big spherical worm-like aggregates with diameter of 2 μm at pH = 5.76, 8.04 and 9.38, respectively. The critical micelle concentration (CMC) of RETA was 0.42 mmol/L, and the surface tension at CMC (γ_cmc) was 38.73 mN/m when pH was 8.04. The RETA had a potential application in delivering doxorubicin hydrochloride (DOX) due to the pH responsiveness. Self-assembly mixed systems of RETA and rosin-based phosphoric acid (DDPD) were designed to improve emulsification. The mixed systems had obvious synergistic effects and unexpected emulsification. The γ_cmc and CMC of mixtures were 41.74 mN/m and 0.20 mmol/L, the size of mixture micelles increased up to 300 nm in the optimum molar ratio of RETA/DDPD (7:3) by TEM and cryo-TEM. It was worth noting that the mixture system formed vesicles in the RETA/DDPD molar ratio of 5:5. The stability time of emulsion with RETA and DDPD as emulsifier were only 63 s and 52 s respectively, but the stability time increased to 234 s in the optimum molar ratio. In addition, the formation mechanisms of micelles at different pH and in various mixtures were discussed in detail. What's more, cytotoxicity results showed that the toxicity of RETA was lower significantly than that of lecithin, a food ingredient in egg yolk and soybean. The cell viability was more than 83% in the high concentration of RETA (4000 μg/ml).

Highly dispersed Au nanoparticles decorated WO3 nanoplatelets: Laser-assisted synthesis and superior performance for detecting ethanol vapor

Loading of noble metal nanoparticles (NPs) on the surfaces of semiconductor oxides to form a hybrid nanostructure is an effective strategy to improve gas-sensing performance. In this study, WO₃ nanoplatelets decorated with Au NPs were prepared by laser ablation in liquids (LAL) with subsequent aging and annealing treatments. Results indicated that Au NPs with an average size of 7.8 ± 2.5 nm were highly dispersed on the surface of WO₃ nanoplatelets. As gas-sensing materials, the obtained Au-decorated WO₃ nanoplatelets showed lower operating temperature of 320 °C and higher response value of 3.5-fold in detecting ethanol molecules compared with pure WO₃ nanoplatelets. Moreover, Au-decorated WO₃ nanoplatelets displayed good selectivity toward ethanol compared with other tested vapors and excellent stability within several cycled measurements. These results can be ascribed to the supported Au NPs, which promote the adsorption and dissociation of oxygen species, eventually resulting in accelerated electron depletion on the surface of Au-WO₃ hybrids.

Combretastatin A4/poly(L-glutamic acid)-graft-PEG conjugates self-assembled to nanoparticles

Combretastatin A4 (CA4) possesses varying ability to cause vascular disruption in tumors, while the short half-life, low water solubility and deactivation of many CA4 analogs during storage limited its antitumor efficacy and drug stability. A novel macromolecular conjugate of CA4 (CA4-PL) was synthesized by covalent bonding of CA4 onto poly(L-glutamic acid)-graft-polyethylene glycol (PLG-g-PEG) via Yamaguchi reaction. The obtained CA4-PL was characterized by ¹H NMR, GPC, and UV methods, and the properties of the nanoparticles composed of CA4-PL, including critical aggregation concentration, size and size distribution, and morphology, were investigated. CA4-PL can self-assemble to form micelle-like nanoparticles of 80~120 nm in diameter, which may have potential to improve the blood circulation period as well as the targetability of CA4, and find applications to treat various tumors when combined with traditional chemotherapy or radio therapy.

Polymeric micelles based on PEGylated chitosan-g-lipoic acid as carrier for efficient intracellular drug delivery

To develop a drug delivery system with long circulation and controlled drug release in cancer cells, polymeric micelles based on PEGylated chitosan-g-lipoic acid were prepared to use as a drug delivery platform. These micelles possessed good stability and were stable in physiological environment and high salt concentrations. The in vitro drug release results implied that the drug carrier could maintain their stability and minimize the payload leakage in systemic circulation, but release drugs faster under intracellular redox condition. Furthermore, the cellular uptake and therapeutic efficacy of the drug carrier were evaluated in vitro, and the results demonstrated that the drug carrier could escape from the endo/lysosomes of tumor cells effectively and present high cytotoxicity to tumor cells. Therefore, this drug delivery system has the potential to serve as a drug carrier for cancer therapy.

A luminescent lanthanide coordination polymer based on energy transfer from metal to metal for hydrogen peroxide detection

A bimetal lanthanide coordination polymer nanoparticle (ATP-Ce/Tb-Tris CPNs) with good biocompatibility was synthesized in Tris-HCl buffer using adenosine triphosphate (ATP) molecules as the bridge ligands. The large absorption cross section and suitable emission energy of Ce³⁺ matching to the adsorption energy of Tb³⁺(⁴f_n) results in the efficient energy transfer from Ce³⁺ to Tb³⁺, thus the synthesized ATP-Ce/Tb-Tris CPNs exhibit the characteristic green emission of Tb³⁺. Such energy transfer from metal to metal in fluorescent lanthanide coordination polymer nanoparticles (Ln-CPNs) has been demonstrated. It is found that the oxidation of Ce³⁺ in ATP-Ce/Tb-Tris CNPs to Ce⁴⁺ would interrupt the energy transfer from Ce³⁺ to Tb³⁺, leading to fluorescence quenching of Tb³⁺. On the basis of this quenching mechanism, ATP-Ce/Tb-Tris CPNs has been successfully used to detect reactive oxygen H₂O₂ with detection limit as low as 2nM. If glucose oxidase is present in the system, glucose can be determined using the ATP-Ce/Tb-Tris CNPs nanosensor.

A unique highly hydrophobic anticancer prodrug self-assembled nanomedicine for cancer therapy

In contrast with common thought, we generated highly hydrophobic anticancer prodrug self-assembled nanoparticles without the aid of surface active substances, based on the conjugation of docetaxel to d-α-tocopherol succinate. The reduction-sensitive prodrug was synthesized with a disulfide bond inserted into the linker and was compared with a control reduction-insensitive prodrug. The morphology and stability of self-assembled nanoparticles were investigated. Cytotoxicity and apoptosis assays showed that the reduction-sensitive nanoparticles had higher anticancer activity than the reduction-insensitive nanoparticles. The reduction-sensitive nanoparticles exhibited favorable in vivo antitumor activity and tolerance compared with docetaxel Tween80-containing formulation and the reduction-insensitive nanoparticles. Taken together, the unique nanomedicine demonstrated a number of advantages: (i) ease and reproducibility of preparation, (ii) high drug payload, (iii) superior stability, (iv) prolonged circulation, and (v) improved therapeutic effect. This highly reproducible molecular assembly strategy should motivate the development of new nanomedicines.

Self-assembling N-(9-Fluorenylmethoxycarbonyl)-l-Phenylalanine hydrogel as novel drug carrier

Supramolecular hydrogel as a novel drug carrier was prepared from N-(9-Fluorenylmethoxycarbonyl) (Fmoc) modified l-phenylalanine. Its different properties like stability at different pH, temperature and rheology were evaluated in reference to salicylic acid (SA) as a model drug, entrapped in the supramolecular hydrogel network. The release behaviour of SA drug in supramolecular hydrogel was investigated by UV-vis spectroscopy. The influence of hydrogelator, pH values of the accepting media, temperature and concentration of SA drug on the release behaviour was investigated under static conditions. The results indicated that the release rate of SA in the supramolecular hydrogels was slightly retarded with an increase of the hydrogelator concentration. Also, the release rates of SA increased with an increase of temperature and its concentration. Furthermore, the release behaviour of SA was found to be different at various pH values in buffers. The study of the release kinetics indicated that the release behaviour of SA from the carrier was in accord with the Peppas model and the diffusion controlled mechanism involved in the Fickian model.

Gold nanoparticles modified with self-assembled hybrid monolayer of triblock aptamers as a photoreversible anticoagulant

We demonstrated that thrombin-binding aptamer-conjugated gold nanoparticles (TBA-Au NPs), prepared from a self-assembled hybrid monolayer (SAHM) of triblock aptamers on Au NPs (13 nm), can effectively inhibit thrombin activity toward fibrinogen. The first block poly(adenine) at the end of the triblock TBA was used for the self-assembly on Au NP surface. The second block, in the middle of TBA, was composed of oligonucleotides that could hybridize with each other. The third block, containing TBA15 (15-base, binding to the exosite I of thrombin) and TBA29 (29-base, binding to the exosite II of thrombin) provided bivalent interaction with thrombin. The SAHM triblock aptamers have optimal distances between TBA15 and TBA29, aptamer density, and orientation on the Au NP surfaces. These properties strengthen the interactions with thrombin (Kd=1.5 × 10(-11)M), resulting in an extremely high anticoagulant potency. The thrombin clotting time mediated by SAHM TBA15/TBA29-Au NPs was >10 times longer than that of four commercially available drugs (heparin, argatroban, hirudin, or warfarin). In addition, the rat-tail bleeding assay time further demonstrated that the SAHM TBA15/TBA29-Au NPs were superior to heparin. The SAHM TBA15/TBA29-Au NPs exhibited excellent stability in the human plasma (half-life >14 days) and good biocompatibility (low cytotoxicity and hemolysis). Most interestingly, the inhibition by SAHM TBA15/TBA29-Au NPs was controllable by the irradiation of green laser, via heat transfer-induced TBA release from Au NPs. Therefore, these easily prepared (self-assembled), low cost (non-thiolated aptamer), photo-controllable, multivalent TBA15/TBA29-Au NPs (high density of TBA15/TBA29 on Au NPs) show good potential for the treatment of various diseases related to blood-clotting disorders. Our study opens up the possibility of regulation of molecule binding, protein recognition, and enzyme activity using SAHM aptamer-functionalized nanomaterials.

A Facile Self-assembly Synthesis of Hexagonal ZnO Nanosheet Films and Their Photoelectrochemical Properties

Here, large-scale and uniform hexagonal zinc oxide (ZnO) nanosheet films were deposited onto indium tin oxide (ITO)-coated transparent conducting glass substrates via a facile galvanic displacement deposition process. Compared with other commonly used solution methods, this process avoids high temperature and electric power as well as supporting agents to make it simple and cost-effective. The as-fabricated ZnO nanosheet films have uniform hexagonal wurtzite structure. The photoelectrochemical (PEC) cell based on ZnO nanosheet film/ITO photoelectrode was also fabricated and its performance was improved by optimizing the solution concentration. A higher photocurrent density of ~500 μA cm^-2 under AM 1.5 G simulated illumination of 100 mW cm^-2 with zero bias potential (vs. Ag/AgCl electrode) was obtained, which may ascribe to the increased surface-to-volume ratio of disordered ZnO nanosheet arrays. Our developed method may be used to deposit other oxide semiconductors, and the ZnO nanosheet film/ITO PEC cell can be used to design low-cost optoelectronic and photoelectrochemical devices.

Mussel-inspired bioceramics with self-assembled Ca-P/polydopamine composite nanolayer: preparation, formation mechanism, improved cellular bioactivity and osteogenic differentiation of bone marrow stromal cells

The nanostructured surface of biomaterials plays an important role in improving their in vitro cellular bioactivity as well as stimulating in vivo tissue regeneration. Inspired by the mussel's adhesive versatility, which is thought to be due to the plaque-substrate interface being rich in 3,4-dihydroxy-l-phenylalamine (DOPA) and lysine amino acids, in this study we developed a self-assembly method to prepare a uniform calcium phosphate (Ca-P)/polydopamine composite nanolayer on the surface of β-tricalcium phosphate (β-TCP) bioceramics by soaking β-TCP bioceramics in Tris-dopamine solution. It was found that the addition of dopamine, reaction temperature and reaction time are three key factors inducing the formation of a uniform Ca-P/polydopamine composite nanolayer. The formation mechanism of a Ca-P/polydopamine composite nanolayer involved two important steps: (i) the addition of dopamine to Tris-HCl solution decreases the pH value and accelerates Ca and P ionic dissolution from the crystal boundaries of β-TCP ceramics; (ii) dopamine is polymerized to form self-assembled polydopamine film and, at the same time, nanosized Ca-P particles are mineralized with the assistance of polydopamine, in which the formation of polydopamine occurs simultaneously with Ca-P mineralization (formation of nanosized microparticles composed of calcium phosphate-based materials), and finally a self-assembled Ca-P/polydopamine composite nanolayer forms on the surface of the β-TCP ceramics. Furthermore, the formed self-assembled Ca-P/polydopamine composite nanolayer significantly enhances the surface roughness and hydrophilicity of β-TCP ceramics, and stimulates the attachment, proliferation, alkaline phosphate (ALP) activity and bone-related gene expression (ALP, OCN, COL1 and Runx2) of human bone marrow stromal cells. Our results suggest that the preparation of self-assembled Ca-P/polydopamine composite nanolayers is a viable method to modify the surface of biomaterials by significantly improving their surface physicochemical properties and cellular bioactivity for bone regeneration application.

Silk microgels formed by proteolytic enzyme activity

The proteolytic enzyme α-chymotrypsin selectively cleaves the amorphous regions of silk fibroin protein (SFP) and allows the crystalline regions to self-assemble into silk microgels (SMGs) at physiological temperature. These microgels consist of lamellar crystals in the micrometer scale, in contrast to the nanometer-scaled crystals in native silkworm fibers. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and zeta potential results demonstrated that α-chymotrypsin utilized only the non-amorphous domains or segments of the heavy chain of SFP to form negatively charged SMGs. The SMGs were characterized in terms of size, charge, structure, morphology, crystallinity, swelling kinetics, water content and thermal properties. The results suggest that the present technique of preparing SMGs by α-chymotrypsin is simple and efficient, and that the prepared SMGs have useful features for studies related to biomaterial and pharmaceutical needs. This process is also an easy way to obtain the amorphous peptide chains for further study.