Au Core-shell Nanoparticles Research Articles

Facile Synthesis of CTAB Coated Au-Ag Core-Shell Nanoparticles and their Catalytic and Antibacterial Activity

Facile Synthesis of CTAB Coated Au-Ag Core-Shell Nanoparticles and their Catalytic and Antibacterial Activity

Tuning the plasmon resonance of Au-Ag core-shell nanoparticles: The influence on the visible light emission for inorganic fluorophores application

In this study, the gold and gold-silver (Au-Ag) core-shell nanoparticles were synthesized via chemical reduction method at different types and quantities of precursor materials. Initially, the gold nanoparticles were prepared with different reducing agents (i.e., sodium borohydride, sodium citrate, and ascorbic acid) and their composites. The optical absorbance, morphology, and size distribution of gold nanoparticles were analyzed to observe the best deposition conditions, used for the Au-Ag core-shell synthesis. Then, the Au-Ag core-shell nanoparticles were grown at four different quantities (i.e., 175 µL, 200 µL, 225 µL, and 250 µL) of silver nitrate precursor to study their effects on the fluorescence property. Optical absorbance, transmission electron microscopy, and laser scanning confocal microscopy were used to characterize the as-synthesized Au-Ag core-shell nanoparticles. From the results of optical absorbance, a single peak is seen for gold nanoparticles while two peaks (major and minor peaks) are observed for Au-Ag core-shell nanoparticles. The sizes of gold and core-shell particles observed from TEM measurement are less than 10 nm, which is typically used in fluorescence applications. The CoSh-2 sample showed a better fluorescence property compared to other core-shell samples. With a rise in exposure time in a laser with a specific wavelength of 405 nm, the intensity of fluorescence declined more for the filter having shorter wavelengths than larger wavelengths. Analyzing these results can be useful to understand the perspective applications of Au-Ag core-shell nanoparticles like synthetic fluorophores application.

Au@4-MBA@Ag NPs labeled SERS lateral flow immunoassay for ultrasensitive and quantitative detection of Salmonella enteritidis

Salmonella enteritidis (S. enteritidis) is a common zoonotic pathogen which can cause acute gastroenteritis characterized with fever, diarrhea and vomiting, posing a serious threat to public health. Rapid and accurate detection of S. enteritidis is in great demand for food safety and timely diseases treatment. In the present study, a surface-enhanced Raman scattering lateral flow immunoassay sensor (SERS-LFIA) was developed for the rapid, ultrasensitive and quantitative detection of S. enteritidis using Au-core Ag-shell nanoparticles sandwiched with Raman molecules. S. enteritidis could be quantitatively detected by SERS-LFIA at concentrations ranging from 1 × 103 to 1 × 107 CFU mL−1, with limits of detection (LOD) of 1 × 105 CFU mL−1 and 1.36 × 102 CFU mL−1 based on naked eye observation and SERS signal analysis, respectively. No cross-reaction was observed from other serotypes of Salmonella and other common pathogens. The coefficient of variation for both the intra- and inter-batch repetitive tests were less than 10%. The recovery rates of spiking feces and eggshells were between 94.8% and 104.7%. Thus, this SERS-LFIA is able to quantitatively detect S. enteritidis in 20 min with high sensitivity, specificity, repeatability, and could be a promising method for the early detection of S. enteritidis in various clinical samples.

Synchronous Fe3+-Enhanced Colorimetric and Liquid SERS-Based Detection of Dopamine Using Core–Shell Plasmonic Nanoparticles

Reliable and direct detection of dopamine (DA), which is a crucial neurotransmitter, is required to diagnose dopamine-related diseases. However, the plasmonic colloidal sensing systems without prefunctionalization (e.g., aptamer, receptor, antibody, etc.) have not been well-established for trace DA detection yet. Herein, we develop a synchronous colorimetric and liquid-surface-enhanced Raman scattering (SERS) sensing system for the sensitive and selective detection of DA neurotransmitters using Au–Ag core–shell nanoparticles (Au@Ag CSNPs). The DA-mediated aggregation of Au@Ag CSNPs changed their plasmon resonance, leading to a distinct color change of the CSNP dispersion and generation of strong electromagnetic “hot spots” in the clustered CSNPs. Notably, the addition of Fe3+ ions to the CSNP dispersion intensified the DA-mediated aggregation of CSNPs, which significantly improved the colorimetric response and liquid-SERS detection of DA in the nanomolar range. Notably, the dual-mode sensing system without prefunctionalization demonstrated highly selective detection of the DA analyte against similar catecholamines (such as norepinephrine and epinephrine), which can be potentially applied to the selective discrimination of trace DA in real samples.

Molecularly imprinted core-shell Au nanoparticles for 2,4-dichlorophenoxyacetic acid detection in milk using surface-enhanced Raman spectroscopy

Surface-enhanced Raman spectroscopy (SERS) has been extensively investigated for rapid and sensitive detection of trace level chemical contaminants in foods. Lack of selectivity to the targeted molecules in food matrices and fairly poor spectral reproducibility remain the main challenges for practical SERS applications. Herein, an ingenious strategy was proposed to hybridize molecularly imprinted polymers (MIPs) with gold nanoparticles as the functional SERS substrate for selective separation and detection of 2,4-dichlorophenoxyacetic acid (2,4-D), a systemic herbicide that has acute toxicity and potential cancer risk. The core-shell AuNPs@MIPs nanoparticles were finely tailored by wrapping an ultrathin layer of MIPs shell on the surface of AuNPs, which allowed selectively separating and enriching 2,4-D to the near surface of AuNPs and ensured the enhancement of Raman scattering signal of the analyte. Embedding an internal standard (i.e., 4-aminothiophenol) inside AuNPs@MIPs for SERS spectral calibration improved the quantification accuracy for 2,4-D. Three-dimensional finite difference time domain (3D-FDTD) simulation demonstrated the maximal electric field enhancement presented in the gap between adjacent AuNPs@MIPs with the theoretical enhancement factor (EF) as high as 5.85 × 106. Chemometric models established using SERS spectra showed accurate differentiation and quantification results for 2,4-D in milk at various contamination levels with a limit of detection (LOD) of 0.011 μg/mL. Our approach to integrate MIPs with noble metallic nanoparticles has great potential for selective and quantitative detection of analytes using SERS for practical agri-food analysis.

Exploring bimetallic Au–Ag core shell nanoparticles reduced using leaf extract of Ocimum tenuiflorum as a potential antibacterial and nanocatalytic agent

Biosynthesis of bimetallic Au–Ag core shell nanoparticle under ambient condition using Ocimum tenuiflorum (Krishna Tulsi) leaf extract is being reported for the first time. For the biosynthesized bimetallic core shell nanoparticles (OTAuAgNPs) visual and spectrophotometric analysis was performed. Development of a deep purple color suggested the creation of OTAuAgNPs. It was then validated by UV–Vis spectrophotometry within 4 h of incubation showing a surface plasmon resonance peak at 560 nm. FESEM-EDAX, FT-IR, particle analyzer and XRD were the analytical techniques employed to characterize the biosynthesized OTAuAgNPs. Using a known antibiotic as a control, OTAuAgNPs (10 mg/ml) had a substantial bacteriostatic effect against Gram + ve (Bacillus subtilis) and Gram −ve (E.coli, Pseudomonas aeruginosa) bacteria. The OTAuAgNPs (6.5 mg) showed good catalytic action for the adsorption of Coomassie brilliant blue R250 dye (CBB) (50 mg/L, 25 mL), confirmed by the reduction in absorbance maxima that is time dependent. A remarkable adsorption of CBB (94.79%) was attained within 120 min, and the results were best-suited PSO and Elovich models with adsorption kinetic constant of 5.96E−04 g/mg.min and 37.81 mg/g.min, respectively. Further the toxicity studies of brilliant blue R250 dye and metabolite of CBB (post nano-remediated dye solution) was carried out on Vigna radiata (green gram) germination and growth. OTAuAgNPs as nanocatalyst remediated water revealed that it was nontoxic. Thus an ecofriendly and cost-effective approach for bimetallic nanoparticle synthesis could be further explored for removal of CBB from wastewater effluents.

Identifying high performance photosensitizer with simultaneous enhancement in fluorescence and singlet oxygen generation, from ‘(Ag/Au)-aggregation-induced emission-active fluorogen’ theranostic nanoparticles

Photodynamic therapy (PDT) is a non-invasive medical technique that combines photosensitizer (PS) molecules and light for cancer treatment. Driven by the need for more personalized medicine, shortened irradiation time and treatment efficiency of PDT are required. Herein, a library of novel theranostic nanoparticle systems for personalized medicine in PDT of cancer is reported. Ag and Au nanoparticles in a size range of 40–50 nm are prepared and used subsequently to synthesize core-shell plasmonic nanoparticles with various thicknesses, either with silica or polymer spacer. Metal-enhanced fluorescence and singlet oxygen generation (SOG) studies are performed for a naphthalene-linked pyridine-based neutral triarylethene as AIE-active PS molecule, by adsorbing on the Ag and Au core-shell nanoparticles. The factors that are varied during the study are the composition of the spacer, and the spacer length. Notably, the enhancement in fluorescence and SOG of the adsorbed AIEgen are observed at the same distance from the metallic surface, resulting from short-range near field plasmonic effect for all the theranostic PS prepared with Ag/Au. The best result, 7.9 fold enhancement in fluorescence and 10.4-fold enhancement in SOG, is observed on loading AIEgen on ∼42 nm Au nanoparticles with polymer spacer, showing promising advancement for image-guided PDT. The probable reasons behind the observed outcomes, are analyzed and discussed in detail, with the help of the Jablonski diagram of the PS molecule. The obtained results from the study has the potential to replace or support the conventional radiation therapy and chemotherapy with serious adverse effects.

Computational Characterization of the Intermixing of Iron Triade (Fe, Co, and Ni) Surfaces and Sub-nanometric Clusters with Atomic Gold.

Dispersion-corrected density functional theory (DFT-D3) is applied to model iron triade (Fe, Co, and Ni) surfaces upon exchange of surface atoms with atomic gold. One first goal is to analyze the contact problem at the triade surface–Au interface and to correlate our findings with recent observations on iron triade nanoparticles (with diameters of around 5 nm) passivated by a few layers of gold. For this purpose, we analyze: (1) the energies of substitution; (2) the restructuring of the iron triade surfaces upon the atomic exchange; (3) the density of the orbitals bearing the largest projection on d(Au) atomic orbitals and, particularly, their overlap with orbitals from neighboring atoms of the triade surfaces; (4) the modification of the electronic density of states; and (5) the redistribution of the electronic density upon intermixing of Au and triade atoms. Inspite of the similarities between Ni, Co, and Fe in the condensed phase, significant differences are found in the features characterizing the exchange process. In particular, we find a better integration of the Au atom on the substitutional site of the Ni(001) surface than on those of the Fe(001) and Co(001) surfaces. This is in agreement with the fact that the electronic density of states is almost indistinguishable before and after Ni–Au intermixing. This outcome is correlated with the experimental observation on the allowing transition of Ni–Au core–shell nanoparticles before reaching the melting temperature. Our second objective is to explore the Au–triade atom intermixing process in sub-nanometric clusters, finding that it is energetically more favored than at solid surfaces yet endothermic at 0 K. This feature is explained as the result of the structural fluxionality characterizing clusters at the sub-nanometer scale. Entropy contributions make mixed Au–Ni clusters more stable than the unmixed counterpart already at 650 K while unmixed Co clusters remain energetically more favored up to 1295 K and iron clusters are predicted to be stable against intermixing over the experimentally relevant range of temperatures (up to 1100 °C). Remarkably, the net charge donated from the three triade atoms to atomic gold upon intermixing is similar in triade sub-nanometeric clusters and at extended triade surfaces. Gold clusters are prone to host Fe, Co, and Ni atoms at the center of their structures and the exchange process is predicted to be exothermic at 0 K even for a small cluster made of 13 atoms. More generally, our work highlights the importance of the polarity of the chemical bond between unlike metal atoms in alloys.

Formation and Application of Core-Shell of FePt-Au Magnetic-Plasmonic Nanoparticles.

Monodispersed FePt core and FePt–Au core–shell nanoparticles (NPs) have been chemically synthesized in liquid solution and with controllable surface-functional properties. The NP size was increased from 2.5 nm for FePt to 6.5 nm for FePt–Au, which could be tuned by the initial concentration of gold acetate coated onto FePt seeding NPs via a seed-mediated formation of self-assembled core–shell nanostructures. The analyses of the interplanar spacing obtained from the high-resolution transmission electron microscopy (HRTEM), selective electron diffraction pattern (SAED), and x-ray diffraction (XRD) confirmed that both FePt core and Au shell belong to the face-centered cubic (fcc) structure. FePt–Au NPs have a surface plasmon resonance (SPR) peak at 528 nm in the visible optical band region, indicating the red shift compared with the typical theoretical value of 520 nm of pure Au NPs. The surface modification and ligand exchange of FePt–Au was using mercaptoacetic acid (thiol) as a phase transfer reagent that turned the NPs hydrophilic due to the functional carboxyl group bond on the surface of presented multifunctional magnetic–plasmonic NPs. The water-dispersible FePt-based NPs conjugated with biomolecules could reach the different biocompatibility requirements and also provide enough heating response that acted as a potential agent for magnetic fluid hyperthermia in biomedical engineering research fields.

Formation of Co–Au Core–Shell Nanoparticles with Thin Gold Shells and Soft Magnetic ε-Cobalt Cores Ruled by Thermodynamics and Kinetics

Bimetallic core–shell nanoparticles (CSNPs), where a ferromagnetic core (e.g., Co) is surrounded by a noble-metal thin plasmonic shell (e.g., Au), are highly interesting for applications in biomedi...

Au-Ag core-shell composite nanoparticles as a selective and sensitive plasmonic chemical probe for l-cysteine detection in Lens culinaris (lentils).

The present work reported is a simple and selective method for the colorimetrical detection of l-cysteine in Lens culinaris (or lentils) using Au–Ag core–shell (Au core Ag shell) composite nanoparticles as a chemical probe. The phenomenon is based on the color change of composite nanoparticles from yellowish brown to light blue, followed by a shift of the localized surface plasmon resonance (LSPR) absorption band in the UV-visible region (i.e., 200–800 nm) with the addition of l-cysteine into the solution of bimetallic nanoparticles. The mechanism for the detection of l-cysteine is based on the electrostatic interaction of the metal ion with the thiol group of the amino acid, which causes the red shift of the LSPR band at 685 nm. The size distribution, morphology, composition and optical properties of the Au–Ag core–shell composite nanoparticles were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), energy dispersive X-ray diffraction (EDX), UV-visible spectrophotometer and Fourier transform infrared spectroscopy (FTIR) techniques. An excellent linearity range for the present method was observed in the range of 20–140 μg mL−1 with a limit of detection at 1.95 μg mL−1 and correlation coefficient (R2) of 0.986. A good% recovery of 4.0% showed the selectivity of the method for l-cysteine determination from sample matrices. The advantageous features of the present method are being simple, rapid, low cost and selectivity towards the determination of l-cysteine in lentils.

Rapid and sensitive detection of rotavirus by surface-enhanced Raman scattering immunochromatography.

A surface-enhanced Raman scattering (SERS) immunochromatographic assay (ICA) has beendeveloped for rapid, ultrasensitive, and quantitative detection of rotavirus in feces using double Raman molecule-labeled Au-core Ag-shell nanoparticles. The Raman signals are generated by 5,5'-dithiobis-(2-nitrobenzoic acid) and the intensity of the characteristic peak at 1334-1cm was detected as the analytical signal. The Raman signals were enhanced by the SERS-enhanced effect of both Au and Ag, the large amount of Raman molecules, and the hot-spot effect in the narrow gap between the Au core and Ag shell. The SERS ICA can quantitatively detect rotavirus in a concentration range of8- 40,000pg/mL, with detection limits of 80pg/mL and 8pg/mL based on naked eye observation and SERS signal detection, respectively. No cross-reaction was observed from other common pathogens. The standard deviation of the intra- and inter-batch repetitive tests is less than 10%, and the coincidence between SERS ICA and RT-qPCR as well as commercial colloidal gold ICA is 100%. The results indicated that this SERS ICA isable to quantitatively detect rotavirus in feces in 20min with high sensitivity, selectivity, reproducibility, and accuracy and might be a promising method for the early detection of rotavirus in clinical analysis.

Plasmon-enhanced photocatalytic hydrogen production by dual dye sensitized ternary composite of MoS3/ Au core-Ag shell nanoparticles/ graphene

Herein, the ternary composite consisting of MoS3, Au core-Ag shell nanoparticles (Au@AgNP), and reduced graphene oxide (rGO) is synthesized for photocatalytic hydrogen evolution reaction. The various characterization studies reveal the co-existence of amorphous MoS3 nanoflakes and the Au@AgNP with the dual absorptions of surface plasmon resonance (SPR) in rGO nanosheets. With the help of single dye sensitization, the ternary composite exhibits a better photocatalytic activity of 9.6 mmol h−1 g−1 with the apparent quantum yield (AQY) of 7.8% and excellent long-term stability under visible light illumination. It also shows the wavelength-dependent photocatalytic activity under the different monochromatic light radiation. Interestingly, the photocatalytic performance of ternary composite further enhances when dual dyes are utilized for sensitization. The optimized photocatalytic reaction system shows a maximum H2 production rate of 10.6 mmol h−1 g−1 with the AQY of 8.6%. The higher activity of ternary photocatalysts is attributed to the amorphous MoS3 nanoflakes with the exposed reactive sites over the conductive rGO nanosheets, which promotes the electron transfer from photoexcited dyes to MoS3. More importantly, the extended SPR absorption of Au@AgNP in-line with the maximum absorption of dye molecules improves light-harvesting ability and efficiently stimulates the dye excitation.

Equilibrium shape of core(Fe)–shell(Au) nanoparticles as a function of the metals volume ratio

The equilibrium shape of nanoparticles is investigated to elucidate the various core–shell morphologies observed in a bimetallic system associating two immiscible metals, iron and gold, that crystallize in the bcc and fcc lattices, respectively. Fe–Au core–shell nanoparticles present a crystalline Fe core embedded in a polycrystalline Au shell, with core and shell morphologies both depending on the Au/Fe volume ratio. A model is proposed to calculate the energy of these nanoparticles as a function of the Fe volume, Au/Fe volume ratio, and the core and shell shape, using the density functional theory-computed energy densities of the metal surfaces and of the two possible Au/Fe interfaces. Three driving forces leading to equilibrium shapes were identified: the strong adhesion of Au on Fe, the minimization of the Au/Fe interface energy that promotes one of the two possible interface types, and the Au surface energy minimization that promotes a 2D–3D Stranski–Krastanov-like transition of the shell. For a low Au/Fe volume ratio, the wetting is the dominant driving force and leads to the same polyhedral shape for the core and the shell, with an octagonal section. For a large Au/Fe ratio, the surface and interface energy minimizations can act independently to form an almost cube-shaped Fe core surrounded by six Au pyramids. The experimental nanoparticle shapes are well reproduced by the model, for both low and large Au/Fe volume ratios.

Thermally Induced Diffusion and Restructuring of Iron Triade (Fe, Co, Ni) Nanoparticles Passivated by Several Layers of Gold.

The temperature-induced structural changes of Fe–, Co–, and Ni–Au core–shell nanoparticles with diameters around 5 nm are studied via atomically resolved transmission electron microscopy. We observe structural transitions from local toward global energy minima induced by elevated temperatures. The experimental observations are accompanied by a computational modeling of all core–shell particles with either centralized or decentralized core positions. The embedded atom model is employed and further supported by density functional theory calculations. We provide a detailed comparison of vacancy formation energies obtained for all materials involved in order to explain the variations in the restructuring processes which we observe in temperature-programmed TEM studies of the particles.

Silver–Gold Bimetallic Alloy versus Core–Shell Nanoparticles: Implications for Plasmonic Enhancement and Photothermal Applications

Bimetallic plasmonic nanoparticles enable tuning of the optical response and chemical stability by variation of the composition. The present numerical simulation study compares Ag-Au alloy, Ag@Au core-shell, and Au@Ag core-shell bimetallic plasmonic nanoparticles of both spherical and anisotropic (nanotriangle and nanorods) shapes. By studying both spherical and anisotropic (with LSPR in the near-infrared region) shapes, cases with and without interband transitions of Au can be decoupled. Explicit comparisons are facilitated by numerical models supported by careful validation and examination of optical constants of Au-Ag alloys reported in literature. Although both Au-Ag core-shell and alloy nanoparticles exhibit an intermediary optical response between that of pure Ag and Au nanoparticles, there are noticeable differences in the spectral characteristics. Also, the effect of the bimetallic constitution in anisotropic nanoparticles is starkly different from that in spherical nanoparticles due to the absence of Au interband transitions in the former case. In general, the improved chemical stability of Ag nanoparticles by incorporation of Au comes with a cost of reduction in plasmonic enhancement, also applicable to anisotropic nanoparticles with a weaker effect. A photothermal heat transfer study confirms that increased absorption by the incorporation of Au in spherical Ag nanoparticles also results in an increased steady state temperature. On the other hand, anisotropic nanoparticles are inherently better absorbers, hence better photothermal sources and their photothermal properties are apparently not strongly affected by the incorporation of one metal in the other.

Magnetic circular dichroism in plasmonic Ag–Au core–shell nanoparticles: how does the magneto-optical activity tune?

Magnetic circular dichroism (MCD) is demonstrated for plasmonic bimetallic nanoparticles. They have an Ag–Au core–shell configuration, which can be synthesized using a seeded growth technique. In the seeded growth process, when the amount of Au (as coating metal) added to the Ag core is small, both ordinary (lower-energy) and extraordinary (higher-energy) modes of localized surface plasmon resonance (LSPR) are detected in optical extinction spectra, suggesting successful formation of well-defined core–shell morphology with a rather thin shell (= AgAu alloy) thickness. Interestingly, the related MCD, showing a typical bisignate magnetoplasmonic response, is more distinct than the extinction signal in the ordinary LSPR mode, but strong damping is found upon thin shell formation. Hence, such bimetallic nanosystems have an advantage of systematic tuning of their magnetoplasmonic behavior, but may not be favorable to obtaining large magneto-optical (MO) activity or MCD amplitudes. The damped MCD response is discussed from a viewpoint of spectral inhomogeneity.

Ultrasensitive dual-signal ratiometric electrochemical aptasensor for neuron-specific enolase based on Au nanoparticles@Pd nanoclusters-poly(bismarck brown Y) and dendritic AuPt nanoassemblies

Neuron-specific enolase (NSE) is viewed as a tumor marker of small cell lung cancer (SCLC) with high diagnostic sensitivity and specificity, whose facile and sensitive detection is critical for clinical diagnosis. In this work, core-shell Au nanoparticles @Pd nanoclusters-poly(bismarck brown Y) (Au@Pd-P(BBY)) and hierarchically dendritic AuPt nanoassemblies (AuPt NAs) were synthesized independently by a one-pot aqueous method. A dual-signal ratiometric electrochemical aptasensor was developed for ultrasensitive determination of NSE based on ferrocene grafted Au@Pd-P(BBY) (Fc-g-Au@Pd-P(BBY)) and reduced graphene oxide/thionine decorated AuPt NAs (rGO/Thi/AuPt NAs). Under optimal conditions, the changes in the peak currents linearly correlate to the NSE concentrations in the wide range of 0.0001―50.0 ng mL–1 with ultralow detection limit (0.03 pg mL–1, S/N = 3). The aptasensor was explored in a diluted human serum sample with acceptable results, showing its great potential in clinical diagnosis and treatment.

Composition and structure of magnetic high-temperature-phase, stable Fe-Au core-shell nanoparticles with zero-valent bcc Fe core.

Advanced quantitative TEM/EDXS methods were used to characterize different ultrastructures of magnetic Fe–Au core–shell nanoparticles formed by laser ablation in liquids. The findings demonstrate the presence of Au-rich alloy shells with varying composition in all structures and elemental bcc Fe cores. The identified structures are metastable phases interpreted by analogy to the bulk phase diagram. Based on this, we propose a formation mechanism of these complex ultrastructures. To show the magnetic response of these magnetic core nanoparticles protected by a noble metal shell, we demonstrate the formation of nanostrands in the presence of an external magnetic field. We find that it is possible to control the lengths of these strands by the iron content within the alloy nanoparticles.

Absorption and plasmon resonance of Bi-metallic core-shell nanoparticles on a dielectric substrate near an external tip

Absorption efficiency profiles and localized surface plasmon resonance (LSPR) wavelengths are reported for metallic core-shell nanoparticles (NPs) placed over a BK7 glass substrate. A numerical study is performed with the vectorized version of the discrete dipole approximation with surface interactions (DDA-SI-v). Gold (Au) and silver (Ag) metallic components are used for the simulations of two different core-shell structures. Absorption enhancement and the hybrid modes of plasmon resonances of the core-shell structures are compared by using a measure that defines a size configuration. It is observed that a small volume fraction of the core sizes results in shell domination over the plasmon response. An additional study is conducted to discern the sensitivity of the refractive index of nanoparticles in different surrounding environments. With a selected core-shell size configuration of Ag-Au pairs, a significant absorption enhancement with a redshift of LSPR wavelength is observed for both Ag core-Au shell and Au core-Ag shell NPs. The absorption behavior of the bare metallic NPs and selected core-shell pairs in proximity to an external probe's tip is also analyzed. The gallium phosphide (GaP) and silicon (Si) tip usage are investigated with transverse electric (TE) and transverse magnetic (TM) wave polarizations. It is observed that the dominance of light polarization on the absorption enhancement of the NPs switches at different wavelengths, where the dielectric transition for tip materials occurs. These findings show the possible targeted uses of metallic core-shell nanoparticles in several areas such as nanomanufacturing, localized heating, bio-sensing, and material detection applications.