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In this study, an excellent monoclonal antibody (mAb) was produced that could sensitively and specifically recognize Flu in fruit samples. The mAb belonged to the IgG2 subclass and had a half-inhibitory concentration (IC 50 ) of 0.59 ng/ml and a limit of detection (LOD) of 0.13 ng/ml. A cross-reactivity test revealed that the mAb had good specificity for Flu. A gold nanoparticle-based lateral-flow immunochromatographic (ICA) strip was used for the rapid screening of Flu in fruit samples. The method had a visual cut-off value of 10 µg/kg for Flu in three different fruit samples when evaluated with the naked eye. The LODs were 5.25, 3.13, and 4.64 µg/kg for Flu in apples, grapes, and oranges, respectively, as obtained with the aid of a strip scan reader. Therefore, this ICA strip assay represented a potential tool for the detection of Flu in fruit samples., (© 2022 Institute of Food Technologists®.)

Optoelectronic effects differentiating absorption of right and left circularly polarized photons in thin films of chiral materials are typically prohibitively small for their direct photocurrent observation. Chiral metasurfaces increase the electronic sensitivity to circular polarization, but their out-of-plane architecture entails manufacturing and performance trade-offs. Here, we show that nanoporous thin films of chiral nanoparticles enable high sensitivity to circular polarization due to light-induced polarization-dependent ion accumulation at nanoparticle interfaces. Self-assembled multilayers of gold nanoparticles modified with L-phenylalanine generate a photocurrent under right-handed circularly polarized light as high as 2.41 times higher than under left-handed circularly polarized light. The strong plasmonic coupling between the multiple nanoparticles producing planar chiroplasmonic modes facilitates the ejection of electrons, whose entrapment at the membrane-electrolyte interface is promoted by a thick layer of enantiopure phenylalanine. Demonstrated detection of light ellipticity with equal sensitivity at all incident angles mimics phenomenological aspects of polarization vision in marine animals. The simplicity of self-assembly and sensitivity of polarization detection found in optoionic membranes opens the door to a family of miniaturized fluidic devices for chiral photonics., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

Chirality is a unifying structural metric of biological and abiological forms of matter. Over the past decade, considerable clarity has been achieved in understanding the chemistry and physics of chiral inorganic nanoparticles 1-4 ; however, little is known about their effects on complex biochemical networks 5,6 . Intermolecular interactions of biological molecules and inorganic nanoparticles show some commonalities 7-9 , but these structures differ in scale, in geometry and in the dynamics of chiral shapes, which can both impede and strengthen their mirror-asymmetric complexes. Here we show that achiral and left- and right-handed gold biomimetic nanoparticles show different in vitro and in vivo immune responses. We use irradiation with circularly polarized light (CPL) to synthesize nanoparticles with controllable nanometre-scale chirality and optical anisotropy factors (g-factors) of up to 0.4. We find that binding of nanoparticles to two proteins from the family of adhesion G-protein-coupled receptors (AGPCRs)-namely cluster-of-differentiation 97 (CD97) and epidermal-growth-factor-like-module receptor 1 (EMR1)-results in the opening of mechanosensitive potassium-efflux channels, the production of immune signalling complexes known as inflammasomes, and the maturation of mouse bone-marrow-derived dendritic cells. Both in vivo and in vitro immune responses depend monotonically on the g-factors of the nanoparticles, indicating that nanoscale chirality can be used to regulate the maturation of immune cells. Finally, left-handed nanoparticles show substantially higher (1,258-fold) efficiency compared with their right-handed counterparts as adjuvants for vaccination against the H9N2 influenza virus, opening a path to the use of nanoscale chirality in immunology., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

In situ quantification and imaging of low-level intracellular microRNAs (miRs) are important areas in biosensor research. Herein, DNA-driven Fe x Cu y Se@upconversion nanoparticle (UCNP) core@satellite nanostructures were developed to probe microRNA-21 (miR-21). Fe x Cu y Se@UCNP probes displayed dual signals: upconversion luminescence (UCL) and magnetic resonance imaging (MRI). In the presence of miR-21, the luminescence signal was restored and the T 2 value was significantly increased because of dissociation of UCNPs from the assemblies. There was a good linear relationship between the dual signals and the expression levels of miR-21 in the range of 0.035-31.824 amol/ng RNA . The limit of detection (LOD) was 0.0058 amol/ng RNA for the luminescence intensity and 0.0182 amol/ng RNA for the MRI signal. This method opens a new avenue for intracellular miR-21 detection with high sensitivity and specificity.

The biological effects of circularly polarized light on living cells are considered to be negligibly weak. Here, we show that the differentiation of neural stem cells into neurons can be accelerated by circularly polarized photons when DNA-bridged chiral assemblies of gold nanoparticles are entangled with the cells' cytoskeletal fibres. By using cell-culture experiments and plasmonic-force calculations, we demonstrate that the nanoparticle assemblies exert a circularly-polarized-light-dependent force on the cytoskeleton, and that the light-induced periodic mechanical deformation of actin nanofibres with a frequency of 50 Hz stimulates the differentiation of neural stem cells into the neuronal phenotype. When implanted in the hippocampus of a mouse model of Alzheimer's disease, neural stem cells illuminated following a polarity-optimized protocol reduced the formation of amyloid plaques by more than 70%. Our findings suggest that circularly polarized light can guide cellular development for biomedical use.

In the present study, chiral Cu x Co y S nanoparticles (NPs) were developed to selectively induce apoptosis of senescent cells using both an alternating magnetic field (AMF) and near infrared (NIR) photon illumination. The chiral effects on living cells were investigated, and d-Cu x Co y S NPs showed about 2.5 times higher of internalized ability than l-NPs. By modifying beta 2 macroglobulin (MG), senescent cells were effectively eliminated by d-Cu x Co y S NPs without damaging the activities of normal cells under AMF and photon illumination. Compared to the individual application of NIR illumination and AMF, their synergistic effect induced the production of caspase-3 with a much shorter treatment time and higher efficiency due to the more serious photon-induced cellular redox and mechanical damage of cellular skeleton. Moreover, the developed strategy was successfully used to remove senescent cells in vivo. This study developed a controllable way of regulating cell activities using chiral NPs, which will provide a valuable way for treating diseases and promoting health., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Dinitolmide is a nitro amide coccidiostat used in poultry feed, and is a potential threat to the environment and human health. In this study, a monoclonal antibody (mAb) against dinitolmide was prepared and an immunochromatographic assay (ICA) was developed to detect residual dinitolmide in chicken tissue. The results show that the mAb exhibited high sensitivity, with a limit of detection as low as 9.01 ng mL-1. A cross reactivity test revealed that the mAb also had good specificity for dinitolmide. This ICA method showed a visible limit of detection of 2.5 μg kg-1, and a cut-off value of 25 μg kg-1 for testing dinitolmide in chicken sample extract by using the naked eye. Importantly, these observations using our ICA, were comparable to other methods of detection such as liquid chromatography, tandem mass spectrometry and indirect competitive enzyme-linked immunosorbent assays (IC-ELISA). These data suggest that our ICA method is a reliable, portable, and high-throughput method for the detection of dinitolmide residues in chicken tissue.

It is a significant challenge to achieve controllable self-assembly of superstructures for biological applications in living cells. Here, a two-layer core-satellite assembly is driven by a Y-DNA, which is designed with three nucleotide chains that hybridized through complementary sequences. The two-layer core-satellite nanostructure (C 30 S 5 S 10 NS) is constructed using 30 nm gold nanoparticles (Au NPs) as the core, 5 nm Au NPs as the first satellite layer, and 10 nm Au NPs as the second satellite layer, resulting in a very strong circular dichroism (CD) and surface-enhanced Raman scattering. After optimization, the yield is up to 85%, and produces a g-factor of 0.16 × 10 -2 . The hybridization of the target microRNA (miRNA) with the molecular probe causes a significant drop in the CD and Raman signals, and this phenomenon is used to detect the miRNA in living cells. The CD signal has a good linear range of 0.011-20.94 amol ng RNA -1 and a limit of detection (LOD) of 0.0051 amol ng RNA -1 , while Raman signal with the range of 0.052-34.98 amol ng RNA -1 and an LOD of 2.81 × 10 -2 amol ng RNA -1 . This innovative dual-signal method can be used to quantify biomolecules in living cells, opening the way for ultrasensitive, highly accurate, and reliable diagnoses of clinical diseases., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In this study, we produced a sensitive and specific monoclonal antibody (mAb) against diclazuril based on a new hapten. The mAb, which belongs to the IgG2 subclass, had a 50%-inhibitory concentration of 0.36 ng/mL. A cross reactivity test revealed that the mAb had good specificity for diclazuril. A gold nanoparticle-based lateral-flow strip was assembled for the rapid screening of diclazuril in raw chicken breast and thigh samples. The strip assay had a visual limit of detection (LOD) of 2 μg/kg and a cut-off value of 20 μg/kg for diclazuril in chicken samples when evaluated with the naked eye. With the aid of a strip scan reader, the proposed assay obtained a quantitative measurement for diclazuril with an LOD of 1.08 μg/kg. Therefore, this gold nanoparticle-based lateral-flow strip assay represents a potentially useful tool for on-site detection and rapid initial screening of diclazuril in chicken samples., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Senescence is a state of stable cell cycle arrest that can escape apoptosis and lead to aging and numerous age-related diseases. In this study, an upconversion-nanoparticle (UCNP)-centered Au 20 -Au 30 nanoparticles tetrahedron (UAuTe) is prepared by DNA hybridization, which can selectively accelerate the clearance of senescent cells. When the beta-2-microglobulin antibody (anti-B2MG) on the Au NPs recognizes senescent cells, the application of near-infrared (NIR) light induces the disassembly of the UAuTe by breaking the boronic ester linkage. Subsequently, the Granzyme B exposed on the UCNPs induces apoptosis in senescent cells, which can then be tracked by changes in fluorescence. It is found that, as compared to single Granzyme B, the UAuTe can not only control the Granzyme B delivery by NIR-responsivity, but also synergistically target and activate the Granzyme B in the senescent cell without the need of perforin. Moreover, this tool is applied successfully in vivo; the results demonstrate that the NIR-responsive tetrahedron can restore renal function, tissue homeostasis, fur density, and athletic ability in a mouse model of senescence after 30 d of treatment. The NIR-induced tetrahedron provides a practical strategy for clinical diagnosis and therapy, particularly for aging and age-related diseases., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In the present study, a tetrahedron probe with encoded internal reference nanoparticles (NPs) was self-assembled by a complementary nucleic acid aptamer for simultaneous ratiometric detection of telomerase (TE) and epithelial cell-adhesion molecule (EpCAM) in living cells. In the presence of a target, the dissociation of gold (Au) NPs, which was modified with corresponding tags, resulted in decreased surface-enhanced Raman scattering (SERS) signals. In addition, the ratios of Raman intensity at 1346 cm -1 /1096 cm -1 (TE) and 1614 cm -1 /1096 cm -1 (EpCAM) compared with the internal reference were demonstrated to quantify the level of TE and EpCAM, respectively, and can eliminate certain background noise. A good linear relationship was observed between them, and the linear range of TE and EpCAM in HeLa cells was 0.7 × 10 -12 to 37.5 × 10 -12 IU and 1.24 to 75.48 pg/mL with a limit of detection (LOD) of 7.6 × 10 -16 IU and 0.53 pg/mL, respectively, which were consistent with the results of Raman confocal imaging. Meanwhile, the versatility and specificity of the developed probes were confirmed in cell lines. These results provide a reliable and ultrasensitive strategy for the in situ detection of biomarkers and a new method for SERS-based tetrahedrons in the early diagnosis of cancer.

Heterodimers of upconversion nanoparticles (UCNPs) and gold yolk-shell nanoparticles are fabricated for the quantification of polymyxin-B-resistant Escherichia coli. They produce two signals, circular dichroism (CD) and upconversion luminescence (UCL). Interestingly, due to the different affinity of polymyxin B for sensitive and resistant strain, as the concentration of polymyxin B increases, the amount of UCNPs in sensitive bacteria increases sharply, increasing the intracellular UCL signal at a low polymyxin B concentration immobilized on the UCNP. The CD intensity is correspondingly reduced as the amount of UCNPs in solution decreased. Meanwhile, for polymyxin-B-resistant strain, the intracellular UCL increases slowly even in a high polymyxin B concentration, and the CD intensity in solution is also enhanced because of the inefficient entering of UCNP. Therefore, based on the concentration of polymyxin B coupled to the UCNPs, the levels of polymyxin-B-resistant bacteria can be detected with dual signals. Importantly, with 980 nm irradiation, both polymyxin-B-sensitive strains and polymyxin-resistant bacteria used to induce infection in mice are detected with UCL imaging in vivo and treated well with photodynamic therapy. This novel dual-mode heterodimer has potential utility for the advanced surveillance and control of drug-resistant bacteria., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A colloidal gold immunochromatographic assay based on a generic monoclonal antibody is developed for the simultaneous detection of benzimidazoles and metabolite residues in milk samples. The monoclonal antibody is prepared using 2-(methoxycarbonylamino)-3H-benzimidazole-5-carboxylic acid as the hapten, and it can recognize 11 types of benzimidazoles simultaneously. The immunochromatographic strip is assembled and labeled using gold nanoparticles. This strip can detect 11 benzimidazoles including albendazole, albendazole s-oxide, albendazole sulfone, fenbendazole, fenbendazole sulfone, flubendazole, mebendazole, parbendazole, oxfendazole, oxibendazole, and carbendazim within 15 min in milk samples. Results are obtained visually with the naked eye, and the cutoff values and the visual limit of detection values for these benzimidazoles are 25, 6.25, 12.5, 12.5, 50, 25, 50, 50, 50, 6.25, and 25 ng mL -1 , and 6.25, 3.125, 3.125, 1.56, 12.5, 6.25, 12.5, 12.5, 6.25, 0.78, and 12.5 ng mL -1 , respectively. Results are also obtained using a hand-held strip scan reader, with calculated limit of detection values for these benzimidazoles of 0.83, 0.77, 1.83, 0.98, 7.67, 3.50, 3.96, 5.71, 0.92, 0.59, and 1.69 ng mL -1 , respectively. In short, the developed paper sensor is a useful tool for rapid and simple screening of residues of benzimidazoles in milk samples., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Designing chiral materials to manipulate the biological activities of cells has been an important area not only in chemistry and material science, but also in cell biology and biomedicine. Here, we introduce monolayer plasmonic chiral Au nanoparticle (NP) films modified with L- or D-penicillamine (Pen) to be developed for cell growth, differentiation, and retrieval. The monolayer films display high chiroptical activity, with circular dichroism values of 3.5 mdeg at 550 nm and 26.8 mdeg at 775 nm. The L-Pen-NP films accelerate cell proliferation, whereas the D -Pen-NP films have the opposite effect. Remote irradiation with light is chosen to noninvasively collect the cells. The results demonstrate that left circularly polarized light improves the efficiency of cell detachment up to 91.2% for L-Pen-NP films. These findings will facilitate the development of cell culture in biomedical application and help to understand natural homochirality.

Self-assembled nanostructures have been used for the detection of numerous cancer biomarkers. In this study, a gold-upconversion-nanoparticle (Au-UCNP) pyramid based on aptamers is fabricated to simultaneously detect thrombin and prostate-specific antigen (PSA) using surface-enhanced Raman scattering (SERS) and fluorescence, respectively. The higher the concentration of thrombin, the lower the intensity of SERS. PSA connected with the PSA aptamer leads to an increase in fluorescence intensity. The limit of detection of thrombin and PSA reaches 57 × 10 -18 and 0.032 × 10 -18 m, respectively. In addition, the pyramid also exhibits great target specificity. The results of human serum target detection demonstrate that the Au-UCNP pyramid is an excellent choice for the quantitative determination of cancer biomarkers, and is feasible for the early diagnosis of cancer., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Alpha-fetoprotein (AFP) and mucoprotein1 (mucin-1) are two important disease biomarkers. Self-assembled gold nanoparticles (AuNPs) and upconversion nanoparticle (Au-Au-UCNP) trimers based on aptamers were developed for the ultrasensitive detection of AFP and mucin-1. The Au-Au-UCNP trimers produced ideal optical signals, with prominent Raman enhancement and fluorescence quenching effects. The surface-enhanced Raman scattering (SERS) intensity decreased in the presence of mucin-1 and the luminescence intensity increased in the presence of AFP. A limit of detection (LOD) of 4.1 aM and a wide linear range of 0.01-10 fM for the detection of mucin-1 were obtained with this SERS-encoded sensing system. Using the luminescence-encoded sensing system, a LOD of 0.059 aM and a wide linear range of 1-100 aM for the detection of AFP were obtained. These LODs are the lowest values reported so far. This approach has the advantage of detecting two disease biomarkers simultaneously.

Reliable and ultrasensitive quantification of dopamine (DA) is essential in the precise diagnotherapy of neurological diseases. In this study, dual mode counterpropagating-responsive gold@silver nanoparticle-gold nanorod (Au@AgNP-AuNR) nano-assemblies were fabricated for the precise quantification of DA. The plasmonic Au@AgNP-AuNR assemblies possessed high surface-enhanced Raman scattering (SERS) activity and strong fluorescence quenching, due to the prominent electromagnetic enhancement between the hotspots of the assemblies. In the presence of a DA target, the Au@AgNP-AuNR assemblies dissociated, leading to an increase in fluorescence intensity and a decrease in SERS intensity. The limit of detection (LOD) of DA was 0.04 fM and 0.02 fM by the fluorescence method and SERS method, respectively. The linear range was 0.1-10 fM. These findings demonstrated that the simultaneous positive fluorescence response and negative SERS response ensured the accurate detection of DA, which opens up a new avenue for the early diagnotherapy of neurological diseases.

Circular dichroism (CD) has allowed the construction of various chiral nanomaterials for different applications, including biosensing. However, the determination of a simple target-specific, economical, and biocompatible platform using CD with intracellular detection and in situ molecular probing is still required. Here, we show that a DNA zip-fastener structure self-assembled chiral-aptasensor based on gold nanoparticle heterodimers provided an outstanding capability to quantify adenosine-5'-triphosphate (ATP) by addition. The conjugation of two ATP molecules to an adenosine aptamer allowed the formation of a stable ring structure, which formed an ATP-ring adhesive scaffold upon interaction with DNA complementary sequences linked with large gold nanoparticles, the latter were able to drop and result in a decrease in CD signal. We also showed that these low-cytotoxicity and polyethylene glycol (PEG)-steady nanoconjugates were also a one-step incubation technique for the quantification and monitoring of ATP in living cells modified by cell penetrating peptides (TAT) or Cy5. The results showed that the linear intracellular detection range was from 1.5 to 4.2 mM with a limit of detection (LOD) of 0.2 mM. Our findings suggest that this chiroplasmonic sensor is a promising approach for investigating biogenic biomolecules inside cells and living organisms and for assessing their biological activity.

A surface-enhanced Raman scattering (SERS) sensor based on gold nanostar (Au NS) core-silver nanoparticle (Ag NP) satellites was fabricated for the first time to detect aflatoxinB1 (AFB1). We constructed the SERS sensor using AFB1 aptamer (DNA1)-modified Ag satellites and a complementary sequence (DNA2)-modified Au NS core. The Raman label (ATP) was modified on the surface of Ag satellites. The SERS signal was enhanced when the satellite NP was attached to the Au core NS. The AFB1 aptamer on the surface of Ag satellites would bind to the targets when AFB1 was present in the system, Ag satellites were then removed and the SERS signal decreased. This SERS sensor showed superior specificity for AFB1 and the linear detection range was from 1 to 1000 pg mL(-1) with the limit of detection (LOD) of 0.48 pg mL(-1). The excellent recovery experiment using peanut milk demonstrated that the sensor could be applied in food and environmental detection.

In this paper, gold–silver nanoparticle (AuNP–AgNP) heterodimers were assembled with highly yield as an active SERS substrate, based on antigen–antibody immunoreaction. The developed SERS sensor has successful achieved the ultrasensitive detection of folic acid (FA) with the limit of detection (LOD) as 0.86 pg/mL. And the linear range was from 0.005 ng/mL to 1 ng/mL. The results also demonstrated that this developed method showed high specificity and excellent recovery for the human serum samples, indicating its promising potential in bio-diagnosis and the environmental monitoring.

Chiral self-assembled nanomaterials with biological applications have attracted great interest. In this study, DNA-driven gold-upconversion nanoparticle (Au-UCNP) pyramids were fabricated to detect intracellular microRNA (miRNA) in real time. The Au-UCNP pyramids are doubly optically active, displaying strong plasmonic circular dichroism (CD) at 521 nm and significant luminescence in 500-600 nm, and therefore can be monitored by both of them. CD will decrease while the luminescence intensity increases in the presence of miRNA. The experimental results show that the CD intensity had an outstanding linear range from 0.073 to 43.65 fmol/10 μg(RNA) and a limit of detection (LOD) of 0.03 fmol/10 μg(RNA), whereas the luminescence intensity ranged from 0.16 to 43.65 fmol/10 μg(RNA) with a LOD of 0.12 fmol/10 μg(RNA). These data indicate that the CD signal is much more sensitive to the concentration of miRNA than the luminescent signal, which is attributed to the strong CD intensity arising from the spin angular momentum of the photon interaction with chiral nanostructures and the plasmonic enhancement of the intrinsic chirality of DNA molecules in the pyramids. This approach opens up a new avenue to the ultrasensitive detection and quantification of miRNA in living cells.

A novel gold immunochromatographic assay (GICA) based on anti-β-lactam receptors was innovatively developed that successfully allowed rapid and simultaneous detection of fifteen β-lactams in milk samples in 5-10 minutes. By replacing the antibodies used in traditional GICA with anti-β-lactam receptors, the difficulty in producing broad specific antibodies against β-lactams was overcome. Conjugates of ampicillin with BSA and goat anti-mouse immunoglobulin (IgG) were immobilized onto the test and control lines on the nitrocellulose membrane, respectively. Since goat anti-mouse IgG does not combine with receptors, negative serum from mice labelled with gold nanoparticles (GNP) was mixed with GNP-labelled receptors. Results were obtained within 20 min using a paper-based sensor. The utility of the assay was confirmed by the analysis of milk samples. The limits of detection (LOD) for amoxicillin, ampicillin, penicillin G, penicillin V, cloxacillin, dicloxacillin, nafcillin, oxacillin, cefaclor, ceftezole, cefotaxime, ceftiofur, cefoperazone, cefathiamidine, and cefepime were 0.25, 0.5, 0.5, 0.5, 1, 5, 5, 10, 25, 10, 100, 10, 5, 5, and 2 ng mL(-1), respectively, which satisfies the maximum residue limits (MRL) set by the European Union (EU). In conclusion, our newly developed GICA-based anti-β-lactam receptor assay provides a rapid and effective method for one-site detection of multiple β-lactams in milk samples.

NaGdF4: Yb, Er nanoparticles, with up-conversion (UC) fluorescence, were used for the first time to build an "off-on" switch based on Au core-UC satellites for thrombin detection. We fabricated the fluorescence sensor using thrombin aptamer modified Au core and complementary sequence modified UC satellites in liquid phase. With optimized assembled conditions, the yield of Au core-UC satellites achieved 80%. The fluorescence of UC nanoparticles quenched when satellite NP attached to Au core NP. Thrombin aptamer on the surface of Au core would bind to targets when thrombin existed in the system, then UC satellites were released and the quenched fluorescence recovered. The sensor showed high specificity for thrombin compared with other biomolecules and the limit of detection reached 3.5 fg/mL. Application of this sensor to detect targets in human serum also achieved satisfactory results. The purpose of this work was to build an ultrasensitive sensor based on Au core-UC satellites for thrombin detection in human serum to achieve diagnosis of diseases., (Copyright © 2015 Elsevier B.V. All rights reserved.)

For the first time, we demonstrated the fabrication of silver nanoparticle ornamented-gold nanoparticle pyramids (Ag-Au Pys) using an aptamer-based self-assembly process and investigated their surface-enhanced Raman scattering (SERS) properties in the detection of vascular endothelial growth factor (VEGF). Under optimized conditions, the SERS signal was negatively related to VEGF concentration over the range 0.01-1.0 fM and the limit of detection (LOD) was as low as 22.6 aM. The matrix effect and the specificity of this developed method were further examined, and the results showed that the superstructure sensor was ultrasensitive and highly selective. This developed aptamer-based SERS detection method suggests that it may be a promising strategy for a variety of sensing applications., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Surface-Enhanced Raman Spectroscopy (SERS) is a powerful analytical technique for detecting trace analytes using noble metal nanoparticles. In this paper, we present a novel approach to construct a high-performance SERS sensing platform using self-assembled gold nanoparticles on aminated glass capillaries. The surface self-assembly technology ensures uniformity and repeatability of the SERS substrate, addressing the challenges of poor reproducibility observed in conventional methods. The 30 nm gold nanoparticles exhibit excellent plasmonic properties and biocompatibility, making them ideal candidates for SERS applications. We conducted SERS detection using Rhodamine 6G (R6G) as probe molecules, achieving a minimum detectable concentration of 0.1 nM for the AuNPs/GS substrate and 0.1 pM for the S-AuNPs/GC substrate. The S-AuNPs/GC substrate demonstrated commendable uniformity and repeatability, with a relative standard deviation of 12.1 %. Machine learning techniques, including baseline correction, normalization, and smoothing, were employed for data processing, enhancing the accuracy and reliability of the SERS analysis. By employing the K-means clustering algorithm, we identified three distinct groups of spectral characteristics. Additionally, Principal Component Analysis (PCA) allowed visualization and understanding of the clustering results in a two-dimensional space, capturing approximately 86.74 % of the data's variance. The successful construction of a high-performance SERS sensing platform with enhanced sensitivity, accuracy, and reliability, assisted by machine learning, holds great potential for various applications in chemical sensing, environmental monitoring, and biomedical diagnostics. [ABSTRACT FROM AUTHOR]

The strong plasmonic chiroptical activities of gold core-DNA-silver shell nanoparticles (NPs) are reported for the first time, using cytosine-rich single-stranded DNA as the template for the guidance of silver shell growth. The anisotropy factor of the optically active NPs at 420 nm reaches 1.93 × 10−2. Their chiroptical properties are likely induced by the DNA-plasmon interaction and markedly amplified by the strong electromagnetic coupling between the gold core and silver shell. [ABSTRACT FROM AUTHOR]