Harvesting More Energetic Photoexcited Electrons from Closely Packed Gold Nanoparticles

Ng, Kwan‐Ming; Lai, Samuel Kin-Man; Chen, Ziyong; Cheng, Yu-Hong; Tang, Ho-Wai; Huang, Wei; Su, Yang; Yang, Jun

doi:10.1021/jasms.0c00480

Cited by 7 publications

(9 citation statements)

References 51 publications

(73 reference statements)

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“…Laser fluence is a crucial factor affecting the LDI efficiency . The higher laser fluence can increase the surface temperature of AuNPs, thus promoting the extent of heat transfer for the ion desorption process. ,, Moreover, increasing laser fluence to a critical point can even lead to phase transition/phase explosion for promoting the ion desorption. , To minimize the above effects on the LDI process, 30 nm bare AuNPs and the BP chloride (as the chemical thermometer) were used to determine the optimal laser fluence. Au cluster ions barely detected at the laser fluence of 60 mJ/cm 2 (Figure a) illustrated the onset of the surface ionization of AuNPs.…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, the flattening of the slope at about 160 mJ/cm 2 revealed the phase transition of the 30 nm AuNPs. 17 To prevent AuNPs from surface ionization and minimize the effect of heat generation, the laser fluence at 60 mJ/cm 2 was adopted in the subsequent MS measurements.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…21,32,33 Moreover, increasing laser fluence to a critical point can even lead to phase transition/ phase explosion for promoting the ion desorption. 17,21 To minimize the above effects on the LDI process, 30 nm bare AuNPs and the BP chloride (as the chemical thermometer) were used to determine the optimal laser fluence. Au cluster ions barely detected at the laser fluence of 60 mJ/cm 2 (Figure 3a) illustrated the onset of the surface ionization of AuNPs.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Near-Field-Induced Ionization on Photo-Excited Gold Nanoparticles

Huang,

Lai,

Liang

et al. 2023

J. Phys. Chem. C

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Gold nanoparticles (AuNPs) have been widely utilized as an effective substrate for triggering molecular ionization upon photoexcitation. However, its underlying mechanism(s) remains unclear. Here, by blocking heat transfer and electron transfer on photo-excited AuNPs with a thin layer of silica shell (i.e., Au@SiO2 NPs), the critical role of the enhanced E-field in ionizing nearby molecules was evidenced. The enhanced E-field of the Au core could enhance the protonation of amino acids (via short-range interaction) by polarizing the analyte molecules. In contrast, the polarizability of the Au core showed a more pronounced effect to enhance the metal cationization process (Na+ and K+ adduction via long-range interaction) by polarizing both the analyte molecules and metal ions and was successfully applied to the sensitive analysis of amino acids in human serum.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

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Near-Field-Induced Ionization on Photo-Excited Gold Nanoparticles

Huang,

Lai,

Liang

et al. 2023

J. Phys. Chem. C

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“…In order to clarify the intrinsic mechanism of desorption and ionization enhancement in PbS/Au-layered substrates, the extent of carrier separation reflected from in situ electron transfer on the surface of PbS/Au-layered substrate in vacuum (without solvent effect) was determined by laser excitation mass spectrometry with juglone as an electron acceptor. ,, Figure a shows the total intensities of juglone increased significantly on the surface of PbS/Au-layered substrate compared with the PbS, Au, and Au/PbS controls. By tuning the bandgap of PbS QDs (Figure b), the highest ion intensities of juglone were recorded in the PbS/Au-layered substrate with PbS QDs of narrowest bandgap (0.62 eV).…”

Section: Resultsmentioning

confidence: 99%

Serum Lipidomic Fingerprints Encode Early Diagnosis and Staging of Lung Cancer on a Novel PbS/Au-Layered Substrate

Lai,

Liang,

et al. 2023

ACS Appl. Mater. Interfaces

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Lung cancer (LC) is a major cause of mortality among malignant tumors. Early diagnosis through lipidomic profiling can improve prognostic outcomes. In this study, a uniform PbS/Au-layered substrate that enhances the laser desorption/ionization process, an interfacial process triggered on the substrate surface upon laser excitation, was designed to efficiently characterize the lipidomic profiles of LC patient serum. By controlling the stacking arrangement and particle sizes of PbS QDs and AuNPs, the optimized substrate promotes the generation of excited electrons and creates an enhanced electric field that polarizes analyte molecules, facilitating ion adduction formation ([M + Na] + and [M + K] + ) and enhancing detection sensitivity down to the femtomole level. Combining multivariate statistics and machine learning, a distinct lipidomic biomarker panel is successfully identified for the early diagnosis and staging of LC, with an accurate prediction validated by an area under the curve of 0.9479 and 0.9034, respectively. We also found that 18 biomarkers were significantly correlated with six metabolic pathways associated with LC. These results demonstrate the potential of this innovative PbS/Au-layered substrate as a sensitive platform for accurate diagnosis of LC and facilitate the development of lipidomic-based diagnostic tools for other cancers.

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“…A strong electric field may greatly polarize the analyte molecules to facilitate the formation of the Na + and K + adducts, thus enhancing the total intensities of the analyte ions. Moreover, this enhanced E-field could assist the generation of excited electrons, 34 as evidenced by the more electron transfer (to juglone as the electron acceptor) when the AuNP array with shorter interparticle distances was used (Figure 4b). However, these photoexcited electrons did not enhance heat transfer to the chemical thermometer (BP ions) (Figure 4c), revealing that heat dissipation is not the main pathway for the relaxation of the photoexcited electrons.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Covalent Bonding and Coulomb Repulsion-Guided AuNP Array: A Tunable and Reusable Substrate for Metabolomic Characterization of Lung Cancer Patient Sera

Lai

Guo

et al. 2022

Anal. Chem.

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Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) has gained increased attention in the metabolic characterization of human biofluids. However, the stability and reproducibility of nanoparticle-based substrates remain two of the biggest challenges in high-salt environments. Here, by controlling the extent of Coulomb repulsion of 26 nm positively charged AuNPs, a homogeneous layer of covalently bonded AuNPs on a coverslip with tunable interparticle distances down to 16 nm has been successfully fabricated to analyze small biomolecules in human serum. Compared with the self-assembled AuNP array, the covalently bonded AuNP array showed superior performances on stability, reproducibility, and sensitivity in high-salt environments. The stable attachment of AuNPs maintained a detection reproducibility with a RSD less than 12% and enabled the reusability of the array for 10 experiments without significant signal deterioration (<15%) and carryover effects. Moreover, the closely positioned AuNPs allowed the coupling of photoinduced plasmons to generate an enhanced electric field, which promotes the generation of excited electrons to facilitate the desorption/ionization processes instead of the heat dissipation, thus enhancing the detection sensitivity with detection limits down to the femtomole level. Combined with machine learning methods, the AuNP array has been successfully applied to discover seven biomarkers for differentiating early-stage lung cancer patients from healthy controls. It is anticipated that this simple approach of developing robust AuNP arrays can also be extended to other types of NP arrays for wider applications of SALDI-MS technology.

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Harvesting More Energetic Photoexcited Electrons from Closely Packed Gold Nanoparticles

Cited by 7 publications

References 51 publications

Near-Field-Induced Ionization on Photo-Excited Gold Nanoparticles

Near-Field-Induced Ionization on Photo-Excited Gold Nanoparticles

Serum Lipidomic Fingerprints Encode Early Diagnosis and Staging of Lung Cancer on a Novel PbS/Au-Layered Substrate

Covalent Bonding and Coulomb Repulsion-Guided AuNP Array: A Tunable and Reusable Substrate for Metabolomic Characterization of Lung Cancer Patient Sera

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