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© 2022, The Author(s), under exclusive License to the Materials Research Society.Abstract: In this article, we show the DNA-functionalization of supraparticles, form their network, and manipulate the optical features of these networks by applying a magnetic field. We start with preparing the supraparticles (SPs) of semiconducting InP/ZnSeS/ZnS quantum dots (QDs), plasmonic silver nanoparticles, and superparamagnetic iron oxide nanoparticles. These SPs are prepared by employing azide-functionalized amphiphilic diblock or triblock copolymers as well as by using their combinations. Subsequently, we attached single-stranded DNAs to these SPs by employing copper-free click chemistry. Next, we hybridized DNA-coated QD SPs with the iron oxide SPs and formed a network. By applying a magnetic field, we restructured this network such that the iron oxide SPs are aligned. This led to an anisotropic emission from the QD SPs with a polarization ratio of 1.9. This study presents a proof-of-concept scheme to control the optical features of a self-assembled supraparticle system using an external interaction. We believe that our work will further contribute to the utilization of smart self-assembly techniques in optics and photonics. Impact statement: The self-assembly of the nanoparticles, which lies at the heart of this article, enables achieving unconventional physical responses that cannot be obtained by the individual nanomaterials. Therefore, controlling the self-assembly process can lead to unprecedented control over the mechanical, optical, or electronic features of such novel architectures made of various types of nanoparticles. This smart self-assembly process will undoubtedly enable the realization of novel applications and open new avenues in materials science and engineering. In this article, we employ the self-assembly in two different aspects. First, we self-assembled magnetic, plasmonic, and semiconducting nanoparticles to obtain their supraparticles with the help of various amphiphilic polymers. Next, single-stranded DNA molecules were attached to them for the first time to achieve a precise control over their physical forming a “network of supraparticles of nanoparticles.” As a proof-of concept demonstration, we hybridized DNA-functionalized magnetic supraparticles made of iron oxide nanoparticles and DNA-functionalized light-emitting supraparticles containing InP/ZnSe/ZnS quantum dots. We explored the potential of tailoring the emission characteristics of the emitted light by utilizing an external magnetic field. We observed that under an external magnetic field the hybrid network reshapes; as a result, the polarization of the emitted light can be changed such that polarization anisotropy reaches ~1.9. We believe that our work presented here can initiate advanced-level active polarization control in displays and other light-emitting devices in the future. Considering that LCD-based displays require polarized light to function, the results of this work may serve for realizing efficient polarizer-free displays that rely on the manipulation of the structure under the magnetic field. Graphical abstract: Single-stranded DNA molecules are attached to the supraparticles of semiconductor, metal, and magnetic nanoparticles to tailor optical features of the self-assembled network. An external magnetic field is employed to actively control the polarization of the light emitted by the network of semiconductor and magnetic supraparticles.[Figure not available: see fulltext.]

Organic-inorganic perovskite solar cells have attracted significant attention due to their remarkable performance. The use of alternative metal-oxide charge-transport layers is a strategy to improving device reliability for large-scale fabrication and long-term applications. Here, we report solution-processed perovskite solar cells employing nickel oxide hole-extraction layers produced in situ using an atmospheric pressure spatial atomic-layer deposition system, which is compatible with high-throughput processing of electronic devices from solution. Our sub-nanometer smooth (average roughness of ≤0.6 nm) oxide films enable the efficient collection of holes and the formation of perovskite absorbers with high electronic quality. Initial solar-cell experiments show a power-conversion efficiency of 17.1%, near-unity ideality factors, and a fill factor of >80% with negligible hysteresis. Transient measurements reveal that a key contributor to this performance is the reduced luminescence quenching trap density in the perovskite/nickel oxide structure.

Laponite is a synthetic clay that is known to form gels in aqueous suspensions at low concentrations (0.01 g/cm3). Although it is expected to form lyotropic liquid crystals, such phases usually do not form, as a consequence of laponite's tendency to form gels at concentrations below the threshold for liquid crystal formation. Here we show that macroscopic, birefringent phases of laponite can be prepared through osmotic compression of a laponite solution by an aqueous solution of carboxy methyl cellulose (CMC). We present polarization imaging studies showing how the initially dilute, isotropic laponite phase shrinks while developing typical birefringence colors between crossed polarizers. Using the Michel-Levy interference charts, we were able to extract the refractive index and orientation of the laponite nanodisks in the compressed region. Our observations allow us to propose a tentative state diagram, indicating the concentration regions for which we obtain optically anisotropic gels.

Inspired by the relationship between the well-ordered architecture of aragonite crystals and biopolymers found in natural nacre, we present a facile strategy to construct large-scale organic/inorganic nacre-mimetics with hierarchical structure via a water-evaporation driven self-assembly process. We connect LAPONITE®-nanoclay platelets with each other using carboxymethyl cellulose, a cellulose derivative, thus creating thin, flexible films with a local brick-and-mortar architecture. The dried films show a pronounced resistance against tensile forces allowing for stronger thin films than nacre. In terms of functionalities, we report excellent glass-like transparency along with exceptional shape-persistent flame shielding. We also demonstrate that through metal ion-coordination we can further strengthen the interactions between the polymers and the nanoclays, and thus enhanced mechanical, and thermal properties as well as resistance against swelling and dissolution in aqueous environments. We believe that our simple pathway to fabricate such versatile polymer/clay nanocomposites can open avenues for inexpensive production of environmentally friendly, biomimetic materials in aerospace, wearable electrical devices, and in the food packaging industry.

Here we demonstrate that in the presence of the small, barrel-shaped molecule cucurbit[7]uril (CB[7]) Laponite clay particles undergo a phase transition into a birefringent gel with lamellar struct...

A well-defined amphiphilic graft copolymer comprising a hydrophilic poly(acrylic acid) (PAA) backbone and hydrophobic poly(lactic acid) side chains was synthesized by a combination of reversible addition–fragmentation chain transfer (RAFT) polymerization, ring open polymerization (ROP), and the grafting-from strategy. A well-defined PtBHBMA homopolymer having pendant hydroxyls in every repeated unit was first obtained by RAFT homopolymerization of a OH-containing tert-butyl 2-((4-hydroxybutanoyloxy)methyl)acrylate (tBHBMA) monomer. ROP of lactide was directly initiated by the pendant hydroxyls of PtBHBMA to provide a well-defined poly(tert-butyl acrylate)-g-poly(lactic acid) (PtBA-g-PLA) graft copolymer via the grafting-from strategy without post-polymerization functionality transformation. The hydrophobic PtBA backbone was selectively hydrolyzed into the hydrophilic PAA backbone so as to afford the targeted well-defined PAA-g-PLA amphiphilic graft copolymer (Mw/Mn = 1.17) having equally-distributed carboxyls along the backbone. PAA-g-PLA amphiphilic graft copolymer shows pH-responsive micellization behavior and it can self-assemble into spheres under certain conditions. Doxorubicin (DOX) can be loaded by non-toxic micelles self-assembled by the PAA-g-PLA graft copolymer and its in vitro accumulative release characteristics were investigated by fluorescence spectroscopy. In comparison with free DOX, the DOX-loading nanoparticles display decreased cytotoxicity against SMMC-7721 and SH-SY5Y cells in 48 h because of a sustained release profile of DOX.

The aim of this study was to investigate the effect of incorporation of the nano silica modified with (3-aminopropyl)triethoxysilane (APTES@SiO2) on the degree of conversion, bond strength and biocompatibility of an experimental dental adhesive. An amphiphilic bonding system was used as the experimental dentin bonding sys- tem. The APTES@SiO2 with diameter of 70 nm was prepared and added into the experimental dentin bonding sys- tem as nanofiller, and the effect of the modification on the stability of the nano APTES@SiO2 dispersed in the ex- perimental adhesive was studied. In addition, the morphology, degree of conversion, bond strength to dental re- storative resin and biocompatibility of the experimental adhesives containing nanofiller were tested. After modifica- tion, the dispersion stability of the nano particles in the adhesive was improved. With increasing the content of the nano APTES@SiO2, the rate of light conversion increased significantly. However, the ultimate degree of conver- sion, bond strength to resin and bulk compressive strength was not significantly affected. Compared with the adhe- sive without nanofiller, the adhesive with 2 wt% APTES@SiO2 showed better bond strength to dentin and lower polymerization shrinkage. In addition, the experimental adhesive showed slight cytotoxicity with the incorporation of APTES@SiO2, but it was attenuated at low concentration.

A series of well-defined amphiphilic brush polymers containing hydrophilic poly(ethylene glycol) (PEG) and hydrophobic poly(lactic acid) segments was synthesized by the combination of reversible addition–fragmentation chain transfer (RAFT) polymerization, ring opening polymerization (ROP), and the grafting-from strategy. tert-Butyl 2-((4-hydroxybutanoyloxy)methyl)acrylate (tBHBMA) monomer containing a ROP initiation group (–OH) was first RAFT block copolymerized using a PEG-based chain transfer agent to form two well-defined PEG-b-PtBHBMA diblock copolymers (Mw/Mn ≤ 1.10) bearing pendant hydroxyls in every repeated unit of PtBHBMA segment. Both diblock copolymers directly initiated ROP of lactide by the pendant hydroxyls to provide well-defined poly(ethylene glycol)-b-(poly(tert-butyl acrylate)-g-poly(lactic acid)) (PEG-b-(PtBA-g-PLA)) brush polymers (Mw/Mn ≤ 1.16) without post-polymerization functionality transformation. The target well-defined poly(ethylene glycol)-b-(polyacrylic acid)-g-poly(lactic acid) (PEG-b-(PAA-g-PLA)) amphiphilic brush polymers were achieved by the selective acidolysis of hydrophobic PtBA backbone (tert-butyoxycarbonyls) into hydrophilic PAA backbone (carboxyls) using trifluoroacetic acid. PEG-b-(PAA-g-PLA) brush polymers could self-assemble into spheres with a size of ca. 70–110 nm in aqueous media as evidenced by DLS and TEM. The drug (doxorubicin) loading ability of PEG-b-(PAA-g-PLA) brush polymers was investigated preliminarily by measuring the in vitro cell (SMMC-7721 and SH-SY5Y) viabilities, which showed higher cytotoxicity compared to free DOX.

Long term retention of antimicrobials with effective drug concentration in gingival crevicular fluid (GCF) is of vital importance for the treatment of chronic periodontitis. In this study, a novel epithelial cell-targeting nanoparticle drug delivery system by conjugating minocycline-loaded poly(ethylene glycol)-poly(lactic acid) (PEG-PLA) nanoparticles (NP-MIN) with RGD peptide were developed and administrated locally for targeting periodontitis epithelial cells and enhancing the treatment of periodontitis in dogs. Biodegradable NP-MIN was made with an emulsion/solvent evaporation technique. RGD peptide was conjugated to the surface of nanoparticles via Maleimide group reaction with hydrosulfide in RGD peptide (RGD-NP-MIN). Transmission electron microscopy examination and dynamic light scattering results revealed that RGD-NP-MIN had a sphere shape, with a mean diameter around 106nm. In vitro release of minocycline from RGD-NP-MIN showed that RGD modification did not change the remarkable sustained releasing characteristic of NP-MIN. To elucidate the interaction of RGD-NP and epithelial cells, RGD-NP binding, uptake and cellular internalization mechanisms by calu-3 cells were investigated. It was shown RGD modification significantly enhanced nanoparticles binding and uptake by Calu-3 cells, and RGD-NP uptake was an energy-dependent process through receptor-mediated endocytosis. Both clathrin-associated endocytosis and caveolae-dependent endocytosis pathway were involved in the RGD-NP uptake, and the intracellular transport of RGD-NP was related to lysosome and Golgi apparatus. Finally, in vivo pharmacokinetics of minocycline in the periodontal pockets and anti-periodontitis effects of RGD-NP-MIN on periodontitis-bearing dogs were evaluated. After local administration of RGD-NP-MIN, minocycline concentration in gingival crevicular fluid decreased slowly and maintained an effective drug concentration for a longer time than that of NP-MIN. Anti-periodontitis effects demonstrated that RGD-NP-MIN could significantly decrease symptoms of periodontitis, which was better than any other control group. These findings suggested that these epithelial cell-targeting nanoparticles offered a novel and effective local delivery system for the treatment of periodontitis.

Synthetic LAPONITE®–clay particles with platelet-like shape display strong aging when dispersed in aqueous solutions, preventing the latter from reaching their natural liquid-crystalline equilibrium state. Here we introduce a facile method that successfully prevents this aging behaviour and enables accessing the systems’ liquid-crystal and crystalline phases. We graft the comb-like polymer PLL–PEG (poly(L-lysine)-g-poly(ethylene glycol)) onto the clay surfaces from solution, thereby screening the negative surface charges and thus ensuring steric stabilisation. We show zeta-sizer and rheology measurements, respectively, confirming complete steric coating and that aging of dilute samples is completely suppressed even after a year. Using evaporation as a means to concentrate the particles, we observe various liquid crystalline textures under a polarized optical microscope (POM). Upon sequential spreading and drying, we are also able to obtain transparent films with hierarchical architecture.

A well-defined amphiphilic graft copolymer, consisting of hydrophobic poly(tert-butyl acrylate) (PtBA) backbone and hydrophilic poly(N-vinylcaprolactam) (PNVCL) side chains, was synthesized by successive reversible addition-fragmentation chain transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP). A new acrylate monomer bearing a chlorine-based initiating group, tert-butyl 2-((2-chloropropanoyloxy)methyl)acrylate, was first RAFT homopolymerized in a controlled way to give a well-defined homopolymer with a narrow molecular weight distribution (Mw/Mn=1.15). This homopolymer directly initiated ATRP of N-vinylcaprolactam (NVCL) to afford a well-defined PtBA-g-PNVCL graft copolymer (Mw/Mn=1.22) via the grafting-from strategy without polymeric functionality transformation. PAA-g-PNVCL graft copolymer was prepared by selectively hydrolyzing PtBA-g-PNVCL. Ornidazole (ONZ)-loaded polymeric micelles using PAA-g-PNVCL copolymer as carrier were prepared by physical entrapping. Drug release experiment of the nano-carrier indicated the pH-dependent drug release characteristics.

Purpose A scientific review panel for the US Food and Drug Administration (FDA) recently identified the need for more data on the health risk of mercury exposure from dental amalgam among susceptible populations. We evaluated impacts of low-level mercury exposure on renal function and neurobehavioral and neuropsychological performance among children. Methods Dental histories for 403 children aged 7–11 years in five schools from Xuhui, Shanghai were checked by dentists. Of them, 198 with confirmed amalgam fillings were recruited (exposure group). Reference children (N=205) were those who never had dental amalgam treatment. In May 2004, each child provided a urine sample for measurements of total mercury, N-acetyl-β- d -glucosaminidase activity, microalbumin, and creatinine (Cr). The Child Behavior Checklist, Eysenck Personality Questionnaire, and an intelligence screening test were administered. Results The geometric mean urinary mercury concentration was 1.6 μg/g Cr for children with and 1.4 μg/g Cr for children without amalgam fillings. No differences were found between children with and without fillings for either renal function biomarker, or on neurobehavioral, neuropsychological, or intelligence tests. Conclusions Although urinary mercury concentration was slightly elevated among children with amalgam fillings, we found no evidence of adverse effects on the outcomes evaluated. These results agree with those from recent trials in developed countries.

Wenxin Yao,1 Peicheng Xu,1 Zhiqing Pang,2,3 Jingjing Zhao,2,3 Zhilan Chai,2,3 Xiaoxia Li,4 Huan Li,2,3 Menglin Jiang,2,3 Hongbo Cheng,2,3 Bo Zhang,2,3 Nengneng Cheng4 1Shanghai Xuhui District Dental Center, 2Key Laboratory of Smart Drug Delivery, Ministry of Education, 3Department of Pharmaceutics, School of Pharmacy, Fudan University, 4Department of Pharmacology, School of Pharmacy, Fudan University, Shanghai, People’s Republic of China Background: Rapid local drug clearance of antimicrobials is a major drawback for the treatment of chronic periodontitis. In the study reported here, minocycline-loaded poly(ethylene glycol)-poly(lactic acid) nanoparticles were prepared and administered locally for long drug retention and enhanced treatment of periodontitis in dogs.Methods: Biodegradable poly(ethylene glycol)-poly(lactic acid) was synthesized to prepare nanoparticles using an emulsion/solvent evaporation technique. The particle size and zeta potential of the minocycline-loaded nanoparticles (MIN-NPs) were determined by dynamic light scattering and the morphology of the nanoparticles was observed by transmission electron microscopy. The in vitro release of minocycline from MIN-NPs and in vivo pharmacokinetics of minocycline in gingival crevice fluid, after local administration of MIN-NPs in the periodontal pockets of beagle dogs with periodontitis, were investigated. The anti-periodontitis effects of MIN-NPs on periodontitis-bearing dogs were finally evaluated.Results: Transmission electron microscopy examination and dynamic light scattering results revealed that the MIN-NPs had a round shape, with a mean diameter around 100nm. The in vitro release of minocycline from MIN-NPs showed a remarkably sustained releasing characteristic. After local administration of the MIN-NPs, minocycline concentration in gingival crevice fluid decreased slowly and retained an effective drug concentration for a longer time (12days) than Periocline®. Anti-periodontitis effects demonstrated that MIN-NPs could significantly decrease symptoms of periodontitis compared with Periocline and minocycline solution. These findings suggest that MIN-NPs might have great potential in the treatment of periodontitis. Keywords: minocycline, nanoparticles, periodontitis, local delivery