Seeded Growth Method Research Articles

Highly sensitive metal-enhanced fluorescence platform based on high-quality CdSe/ZnS quantum dots and gold nanodendrites

Fluorescence immunosensors are highly demanded for diagnosing, monitoring and pathogenesis of diseases. Yet, the low sensitivity due to the weak fluorescence intensity of commonly employed fluorescent materials is the major obstacle towards early accurate diagnosis of targeted diseases. Herein, we resolve this issue by designing a highly sensitive fluorescence platform via employing colloidal quantum dots (QDs)-metal nanoparticles hybrid system. The QDs exhibit high chemical, thermal, and optical stability, excellent biocompatibility with ultrahigh quantum yield (∼88 %). They exhibit a core/shell architecture with type-I band alignment. The gold nanodendrites (AuNDs) synthesized via seed growth method with controllable sizes exhibit anisotropic shape, which maximizes the impacts of local surface plasmon resonance to amplify the fluorescence performance of colloidal QDs. Utilizing the designed platform and taking C-reactive protein as a testcase, we achieve ∼17-fold sensitivity improvement compared with metal nanoparticles free sensing platform, and a wide detection range between 0.25 ng/mL and 1000 ng/mL, and a low detection limit of 0.056 ng/mL. The designed sensing platform has been extended for the detection of real blood and tissue samples, and competing results have been delivered compared with the prevailing detecting technique. The present work reports a novel route of designing biological sensing platform through fluorescence amplification, which holds great potential for highly sensitive and throughput detection in clinical applications, and is widely applicable for highly sensitive detection of other biomarkers in biomedical applications.

Unexpected high performance of ZIF-8 membranes for 1,3-butadiene purification

The purification of 1,3-butadiene from C4 hydrocarbon mixtures currently relies on energy-intensive extractive distillation. In this study, we employed ZIF membranes for this challenging separation for the first time, unveiling their superior capability in isolating 1,3-butadiene from other C4 hydrocarbons with similar sizes, including 1-butene, isobutene, and n-butane. This strong sieving effect was evident from two types of ZIF-8 membranes: one with low crystallinity fabricated via the all-vapor-phase ligand-induced permselectivation (LIPS) method and another with high crystallinity synthesized through the seeded growth method. The gas permeances decreased with increasing kinetic diameters, following the order of 1,3-butadiene (4.31 Å) > 1-butene (4.46 Å) > n-butane (4.687 Å) > isobutene (4.84 Å). The LIPS-ZIF-8 membrane exhibited a high 1,3-butadiene permeance of approximately 1.43 × 10−7 mol/m2 s Pa (∼430 GPU) and ideal separation factors of 18, 56, and 134 for 1,3-butadiene over 1-butene, n-butane, and isobutene, respectively. In separating four-component C4 mixtures, these membranes could enrich 1,3-butadiene content from 50% in the feed to 96–98% in the permeate through a single separation step. This unprecedented performance is attributed to differences in C4 diffusivities that span several orders of magnitude.

Piezo-photocatalysis for efficient charge separation to promote CO2 photoreduction in nanoclusters

The substantial emissions of CO2 greenhouse gases have resulted in severe environmental problems, and research on the implementation of semiconductor materials to minimize CO2 is currently a highly discussed subject. Effective separation of interface charges is a major challenge for efficient piezo-photocatalytic systems. Meanwhile, the ultrasmall-sized metal nanoclusters can shorten the distance of electron transport. Herein, we synthesized Au25(p-MBA)18 nanoclusters (Au25 NCs) modified red graphitic carbon nitride (RCN) nanocatalysts with highly exposed Au active sites by in-situ seed growth method. The loading of Au25 NCs on the RCN surface provides more active sites and creates a long-range ordered electric field. It allows for the direct utilization of the piezoelectric field to separate photogenerated carriers during photo-piezoelectric excitation. Based on the above advantages, the rate of CO2 reduction to CO over Au25 NCs/RCN (111.95 μmol g−1 h−1) was more than triple compared to that of pristine RCN. This paper has positive implication for further application of metal clusters loaded semiconductor for piezo-photocatalytic CO2 reduction.

Tailored Energy Funneling in Photocatalytic π-Conjugated Polymer Nanofibers for High-Performance Hydrogen Production.

The creation of artificial high-performance photosynthetic assemblies with a tailorable antenna system to deliver absorbed solar energy to a photosynthetic reaction center, thereby mimicking biological photosynthesis, remains a major challenge. We report the construction of recyclable, high-performance photosynthetic nanofibers with a crystalline π-conjugated polyfluorene core as an antenna system that funnels absorbed solar energy to spatially defined sensitized Co(II) porphyrin photocatalysts for the hydrogen evolution reaction. Highly effective energy funneling was achieved by tuning the dimensions of the nanofibers to exploit the very long exciton diffusion lengths (>200 nm) associated with the highly crystalline polyfluorene core formed using the living crystallization-driven self-assembly seeded growth method. This enabled efficient solar light-driven hydrogen production from water with a turnover number of over 450 for 8 h of irradiation, an H2 production rate of ca. 65 mmol h-1 g-1, and an overall quantum yield of 0.4% in the wavelength region (<405 nm) beyond the absorption of the molecular photocatalyst. The strategy of using a tailored antenna system based on π-conjugated polymers and maximizing exciton transport to a reaction center reported in this work opens up future opportunities for potential applications in other fields such as solar overall water splitting, CO2 reduction, and photocatalytic small molecule synthesis.

Evaluating Antimicrobial Effectiveness of Gold Nanoparticles against Streptococcus oralis.

Biofilm includes many microorganisms that causes the periodontal diseases. The increased drugs resistance against the infectious diseases is a major issue owing to excessive using of a broad spectrum of antibiotics. Recently, metallic nanoparticles (NPs) are being administered to control the growth of different types of microorganisms. For instance, gold nanoparticles (Au NPs) are found to be successful to control and limit the bacterial pathogenicity in the oral cavity without any cytotoxic effects on the human body. Aim. In this paper, it was aimed to detect the antibacterial effect of Au NPs and compare with chlorhexidine (CHX) against Streptococcus oralis (S. oralis) in dental plaque of patients with chronic periodontitis. Materials and Methods. First, supragingival and subgingival plaque samples were collected from the patients suffering from periodontal disease and incubated under aerobic or/and anaerobic conditions. Second, the morphological examination, and biochemical test by Vitec 2 machine are used to confirm the S. oralis species. Third, the synthesis of Au NPs was carried out by seed growth method and their properties were characterized. Finally, the antimicrobial effect of the Au NPs against S. oralis was evaluated by Agar well diffusion method for different Au NPs concentrations (100, 50, 25, 12.5, 6.25, 3.125, 1.562, 0.781, 0.391, 0.195, and 0.097 ppm). CHX was used as the positive control and distilled water as the negative control. The antibacterial activity data were statistically analyzed by least significant difference (LSD) using the Statistical Program for Social Science (SPSS) version 22. Results. The Au NPs with an average particles size of 43 nm, polycrystalline face-centered cubic structure were characterized. The Au NPs at 100 ppm concentration had similar antibacterial effect of CHX for inhibiting the growth of S. oralis, with no significant difference. Conclusions. The Au NPs as an antibacterial agent could be equally effective against S. oralis similar to the CHX when used at higher concentration.

Pb3BP3O12: A new congruent-melting compound with one-dimensional zigzag chains

A new single crystal of Pb3BP3O12 (PBP) was grown by top seeded growth method with the crystal dimensional of 18 mm × 7 mm × 9 mm. Pb3BP3O12 was a congruent-melting compound and crystallized in the orthorhombic space group of Ibca with unit cell parameters of a = 7.0080(2) Å, b = 14.2286(4) Å, c = 21.5469(6) Å and Z = 8. The structure featured a one-dimensional (1D) zigzag chains composed of [B(PO4)3]6- anionic units. Pb atoms located between the anion chains to connect them, forming a 3D network structure. Furthermore, Pb3BP3O12 performed a wide transmittance range from 250 to 2600 nm.

Synthesis and characterization of Au Nanoparticles by seed–growth method use as saturation absorber for visible laser Q-switched pulse generation

Synthesis and characterization of Au Nanoparticles by seed–growth method use as saturation absorber for visible laser Q-switched pulse generation

Synthesis and Assembly of Core–Shell Nanorods with High Quantum Yield and Linear Polarization

AbstractThe seeded growth method offers an efficient way to design core–shell semiconductor nanocrystals in the liquid phase. The combination of seed and shell materials offers wide tunability of morphologies and photophysical properties. Also, semiconductor nanorods (NRs) exhibit unique polarized luminescence which can potentially break the theoretical limit of external quantum efficiency in light emitting diodes based on spherical quantum dots. Although rod‐in‐rod core–shell NRs present higher degree of polarization, most studies have focused on dot‐in‐rod core–shell NRs due to the difficulties in achieving uniform NR seeds. Here, this study prepares high‐quality uniform CdSe NRs by improving the reactivity of the Se source, using a secondary phosphine, namely diphenylphosphine, to dissolve the Se power, along with the conventional tertiary phosphine, namely trioctylphosphine. Starting from these high‐quality NR seeds, this study synthesizes CdSe/CdxZn1−xS/ZnS core–shell NRs with narrow emission bandwidth (29 nm at 620 nm), high PLQY (89%) and high linear polarization (p = 0.90). This study then assembles these core–shell NRs using the confined assembly method and fabricates long‐range‐ordered microarrays with programmable patterns and displaying highly polarized emission (p = 0.80). This study highlights the great potential of NRs for application in liquid crystal displays and full‐color light emitting diodes displays.

Label-Free identification of fentanyl analogues using surface-enhanced Raman scattering and machine learning algorithm

The identification and analysis of drug abuse is crucial for controlling and combating this global public health problem. In this regard, surface-enhanced Raman spectroscopy (SERS) is a highly sensitive detection technique that is fast, non-destructive, and widely used in various fields. In this study, Ag@Au nanowires (Ag@Au NWs) were synthesized using the seed growth method. The SERS performance of Ag@Au NWs was evaluated using R6G as a probe molecule, and the minimum detection concentration of R6G was found to be 10−9 M. Similarly, the minimum detection concentration of fentanyl was observed to be 10−7 M. Furthermore, the study also involved performing routine Raman detection on 10 fentanyl analogs that were structurally similar. Additionally, density functional theory (DFT) calculations were carried out to distinguish between these substances. The Raman spectra calculated by DFT provided vibrational frequencies and normal mode assignments for each species. By comparing normal Raman spectra, SERS and DFT calculated spectrogram data, we assigned characteristic peaks of 10 substances. Finally, principal component analysis was used to reduce the dimension of the data, and support vector machine were further used to classification of SERS spectral data of the above 10 substances, with an accuracy of 96.4%.

Mixed-linker MOF-303 membranes for pervaporation

Metal-organic frameworks (MOFs) hold great promise as porous materials for pervaporation applications. However, the exploration of MOF membranes in this field is still in its early stages. One of the main challenges is the relatively low mass flux and stability of pure MOF membranes compared to other materials used in pervaporation. In this study, we propose a novel approach to enhance the separation performance of MOF membranes for water and ethanol separation. Our strategy involves incorporating the 2,5-thiophenedicarboxylic acid (TDC) linker into the MOF-303 structure, partially replacing the 3,5-pyrazoledicarboxylic acid (PDC) linker. The goal is to increase the aperture size of the microporous channels in the pristine MOF-303 membrane, thereby improving the mass flux. X-ray diffraction characterization, combined with Rietveld refinement, confirmed that the partial substitution of PDC with TDC resulted in an increased pore-limiting diameter (PLD) of MOF-303. For instance, the pristine MOF-303 exhibited a PLD of 5.78 Å, while MOF-303(70/30) with 70% TDC replacement displayed a PLD of 6.02 Å. To fabricate the mixed-linker MOF-303 membranes, we utilized a seeded growth method, which yielded membranes with dense layers, as confirmed by scanning electron microscopy and air permeation characterization. The prepared membranes were subjected to pervaporation tests to evaluate their performance in separating 90 wt.% ethanol at 60 °C. The pristine MOF-303 membrane exhibited notable separation capabilities, with an average flux of 0.071 kg·m−2·hr−1 and a water/ethanol separation factor of 5371. Surpassing the unmodified MOF-303, the mixed-linker MOF-303(50/50) membrane demonstrated improved mass flux and water/ethanol separation factor. Specifically, the MOF-303(50/50) membrane displayed an average flux of 0.092 kg·m−2·hr−1 and a water/ethanol separation factor of 8500. Importantly, the unmodified MOF-303 membrane exhibited instability during prolonged pervaporation operation, whereas the mixed-linker MOF-303(50/50) membrane effectively addressed this issue. Further analysis using in situ Fourier transform infrared spectroscopy and water adsorption characterization revealed that MOF-303(50/50) possessed a strong affinity for water, comparable to the pristine MOF-303. Overall, our study highlights the potential of the mixed-linker approach to optimize the separation performance and stability of MOF-based membranes for pervaporation application.

Editable Au NCs@ZIF-8 nanomaterial-modified paper in situ as well as portable smartphone-assisted sensing assay for the highly sensitive Cu (II) detection in Wilson’s disease

High levels of Cu (II) in the human body can cause kidney dysfunction, liver cirrhosis, and many neurological diseases, such as Wilson’s disease (WD). Therefore, rapid and efficient detection of Cu (II) in urine is highly essential. First, by a simple multiple seeded growth method, the gold nanoclusters (Au NCs) embedded metal-organic framework (ZIF-8) is decorated on cellulose paper to generate a fluorescent Au NCs@ZIF-8 paper. Then the Au NCs@ZIF-8 paper is loaded on the fluidic cartridge integrated with the syringe for ultra-sensitive urine copper detection. The fluorescence paper is intercalated in a reusable fluidic cartridge and attached to a syringe, allowing the fluidic cartridge to flow a amount of samples through the paper. The interaction of Cu (II) with in situ growth of Au NCs@ZIF-8 on the paper induced fluorescence quenching, which fluorescence images can be recorded and analyzed by the portable smartphone-assisted device. Furthermore, a large amount of sample solution was flowed through the Au NCs@ZIF-8 paper, enabling more Cu (II) to react with the Au NCs@ZIF-8 paper on the novel paper-based analytical device (nPAD). Cu (II) detection can be completed by nPAD in 20 mins, and the limit of detection was as low as 9.2 nM. We show the value of the paper device for on-site detection of copper (II) and indicate that it has excellent potential for clinical applications and environmental monitoring.

Development of a method to diagnose endometrial cancer based on the AuNRs-AntiVimentin optical probe.

Endometrial cancer is one of the common gynecological malignancies, and its incidence has been increasing year by year in recent years, raising higher requirements for its rapid diagnosis. In this article, gold nanorods (AuNRs) with localized surface plasmon resonance properties (LSPR) has used to prepare AuNRs-antibody to waveform protein (AuNRs-AntiVimentin) optical probes, and a new method has been constructed that could rapidly detect and identify endometrial cancer tissue sections by polarized light microscopy. AuNRs were prepared by seed growth method using gold chloride as raw material, and the morphology of AuNRs and the optical characteristics of AuNRs-AntiVimentin has characterized by transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), and zeta potential; immunohistochemistry (IHC) and AuNRs-AntiVimentin optical probes have used to detect clinical endometrial cancer, respectively. The AuNRs-AntiVimentin optical probe has been used to detect endometrial cancer tissue sections and found to have good bio-specificity, with no significant difference in the detection of AuNRs-AntiVimentin compared with conventional IHC techniques (p > .05). An optical probe generated by coupling AuNRs with Vimentin antibodies has been obtained to detect and identify endometrial cancer with simple operation and comparable effect to conventional IHC, providing a new method and idea for the rapid detection of endometrial cancer.

Nanocomposites Based on Spin-Crossover Nanoparticles and Silica-Coated Gold Nanorods: A Nonlinear Optical Study.

A nanocomposite based on silica-coated AuNRs with the aminated silica-covered spin-crossover nanoparticles (SCO NPs) of the 1D iron(II) coordination polymer with the formula [Fe(Htrz)2(trz)](BF4) is presented. For the synthesis of the SCO NPs, the reverse micelle method was used, while the gold nanorods (AuNRs) were prepared with the aspect ratio AR = 6.0 using the seeded-growth method and a binary surfactant mixture composed of cetyltrimethylammonium bromide (CTAB) and sodium oleate (NaOL). The final nanocomposite was prepared using the heteroaggregation method of combining different amounts of SCO NPs with the AuNRs. The nonlinear optical (NLO) properties of the hybrid AuNRs coated with different amounts of SCO NPs were studied in detail by means of the Z-scan technique, revealing that the third-order NLO properties of the AuNRs@SCO are dependent on the amount of SCO NPs grafted onto them. However, due to the resonant nature of the excitation, SCO-induced NLO switching was not observed.

Controlling Oxygen Reduction Reaction Activities of Ag@Pt Core–Shell Nanoparticles Via Tuning of Ag in the Surface Layer

Pt layer thickness in [email protected] core-shell nanoparticles prepared via the seeded-growth method can be controlled in the synthesis stage. However, their oxygen reduction reaction (ORR) activity is not solely dependent on the Pt overlayer. Ag is present in the Pt shell and the ORR kinetics are facilitated by increasing the Pt shell thickness with a lessened Ag amount on the surface. More details can be found in article number 2201167, Önder Metin, Sarp Kaya, and co-workers.

Metal seeding growth of three-dimensional perovskite nanowire forests for high-performance stretchable photodetectors

Metal halide perovskites have been ubiquitously utilized in both rigid and flexible optoelectronics with high performance. However, developing perovskites-based stretchable optoelectronics is highly challenging because perovskites are intrinsically not stretchable unlike some organic semiconductors. Here, for the first time, we devised a novel metal seeding growth method to obtain three-dimensional (3D) perovskite nanowire forests (NWFs) with excellent mechanical stretchability, akin to the seeding growth of grass in nature. Benefiting from their intrinsic stretchability, perovskite NWFs-based stretchable photodetectors have been demonstrated with excellent photodetection performance. Under 0% strain, the device dark current is as low as 0.18 nA cm-2 at − 2 V bias, contributing to an ultrahigh light-to-dark current ratio (Ilight/Idark) of 1.1 × 105 under 5.5 mW cm-2 illumination. The device also exhibits a high responsivity of 455.3 mA W-1 and specific detectivity of 8.69 × 1012 Jones. Meanwhile, under 80% strain conditions, the device have shown negligible performance drop, especially in the aspect of Ilight/Idark. Our work reports a novel growth process that leads to intriguing 3D perovskite nanostructures with unique mechanical flexibility and stretchability, in addition to high optoelectronic sensing performance. These appealing properties can find applications in high-performance stretchable and wearable optoelectronics in the future.

Near-Infrared Emission from CdSe-Based Nanoplatelets Induced by Ytterbium Doping

Cadmium selenide (CdSe) nanoplatelets (NPLs) have attracted significant attention thanks to their favorable optical properties, including narrow emission linewidths, reduced Auger recombination, and a high absorption cross section. However, the photoluminescence (PL) quantum yield (QY) in the near-infrared (NIR) region is poor as compared to that in the visible region. Doping of metal ions is proven to be a successful strategy for inducing Stokes-shifted NIR emission. Here, we report the first account of the successful doping of ytterbium (Yb) into CdSe NPLs by a modified seeded-growth method. The successful incorporation of divalent Yb ions into CdSe NPLs resulted in an additional NIR emission apart from their excitonic emission. By optimizing the dopant concentration, we observed an impressive PL QY of ∼55% for these Yb-doped NPLs. Detailed elemental and optical characterizations were conducted to understand the emerging photophysical properties of these Yb-doped NPLs. These NIR-emitting lanthanide-doped CdSe NPLs might have applications in the next-generation bioimaging, night vision, and photodetection.

Uniform Two-Dimensional Crystalline Platelets with Tailored Compositions for pH Stimulus-Responsive Drug Release.

Two-dimensional, size-tunable, water-dispersible particle micelles with spatially defined chemistries can be obtained by using "living" crystallization-driven self-assembly (CDSA) approach. Nevertheless, a major obstacle of crystalline particles in drug delivery application is the difficulty in accessing to cargo within crystalline cores. In the present work, we design four different types of biocompatible two-dimensional platelets with a crystalline poly(ε-caprolactone) (PCL) core, a hydrophobic poly(4-vinylprydine) (P4VP) segment, and a water dispersible poly(N,N-dimethyl acrylamide) (PDMA) block in ethanol by seeded growth method. Transferring those uniform platelets with tailored compositions to an aqueous solution in the presence of a hydrophobic drug leads to efficient encapsulation of the cargo in the P4VP segments via hydrophobic interactions. These drug-loaded platelets exhibit pH-responsive release behavior in aqueous media due to the protonated-deprotonated process of P4VP blocks in acidic and neutral solutions. This work provides initial insight into biocompatible PCL platelets with low dispersity and precise chemistry control in stimulus-responsive drug delivery fields.

Research on a three-dimensional SERS substrate based on a CNTs/Ag@Au/SiO2 composite for detection of fipronil and imidacloprid pesticides.

Surface-enhanced Raman scattering (SERS) has a unique fingerprint spectrum, which allows for rapid, highly sensitive, and non-destructive detection without the need for sample pretreatment. However, SERS substrates have disadvantages such as short storage time and poor reproducibility. In this study, carbon nanotubes, gold, and silver were combined to take advantage of their inherent structural and characteristic properties that enhance the Raman effect. A new type of SERS composite substrate, CNTs/Ag@Au/SiO2, was prepared using a hydrothermal method and seed growth method. The substrate was characterized using transmission electron microscopy (TEM), and the average distance between the core-shell nanoparticles was found to be 3.1 nm, which is more suitable than other gold-silver combined core-shell structures and significantly improves the SERS enhancement factor. The substrate demonstrated high sensitivity even at low concentrations of probe molecules and good uniformity at five randomly selected locations. After storage for 45 days, the substrate still exhibited good stability. In most gold-silver combined core-shell structures, the detection limit for Rhodamine 6G (R6G) is 10-9 mol L-1, while in this substrate, the detection limit for R6G is 10-11 mol L-1. Furthermore, the contribution of the substrate's enhancement was deeply investigated using finite-difference time-domain (FDTD), which revealed that the substrate's hotspots were present in two forms: the "hotspots generated between Ag@Au nanoparticles" and the "hotspots generated between Ag@Au nanoparticles and carbon nanotubes". These two forms of hotspots also demonstrated that the performance brought about by the preparation of the substrate structure was reliable. The simulation results were compared with the experimental results, and the analysis showed that the real environment would have an impact on the substrate's structure during the actual substrate preparation process. Finally, the substrate was used for detecting the pesticide fipronil, and the results showed clear peaks even at a concentration of 0.1 mg L-1. The results indicated that the Raman intensity was linearly exponential with the fipronil solution concentration, with a determination coefficient of R2 = 0.991. This study provides a new SERS substrate for pesticide residue detection and further explores the improvement of pesticide detection limits.

Percolation and jamming properties in limited grain growth of linear objects

The physical and chemical properties of the nanocrystals are highly shape dependent, and shape control has become very important. The seeded growth method enables seeds to grow in a predetermined way. We have already proposed such amodel that can reproduce the granular growth on a triangular lattice and for different growth shapes. In this paper, however, we have introduced a limitation on seed growth up to a certain length. This method can be used when the growth of all seeds have to be limited to the same length, or for a mixture with the different growth limits.The main goal is to investigate how the growing limits affect the values of the percolation threshold and jamming density, and whether large objects significantly affect the percolation threshold. We used growing needle-shaped objects (k-mers) made by a self-avoiding random walk filling the nodes of the triangular lattice. Objects can grow until they reach the growth limit k' defined as the maximum number of lattice nodes belonging to one object. For k' ≥10 percolation is reached for all investigated seed densities. We obtained that the values of the percolation threshold and jamming density are identical for k' ≥10k .Above these values, the percolation threshold and jamming remain unchanged, regardless of the growth limit.Our results also show that when significant growth is allowed, long objects are very rare and do not influence the results.

Preparation of Au nanomaterial particles and medical research

Gold nanoparticles have good stability, ease of operation, sensitive optical properties and good biocompatibility, making them widely used in food safety testing, environmental safety testing and medical detection and analysis. In this work, the main preparation methods of Au nanoparticles are reviewed, including chemical reduction method, two-phase method, seed growth method and template method, as well as the structural characteristics and characteristics of Au nanoparticles. At the same time, the application of Au nanoparticles in biomedicine is elaborated, and the results show that their outstanding surface plasma resonance properties have unique advantages in the field of loading drugs and transporting drugs. Finally, the application of gold nanoparticles in cancer treatment, biochemical analysis and biosensors is prospected.