This work reports the host (semiconductor nanoparticles) sensitized dopant (lanthanides, Ln) photoluminescence in near band gap matched Sn(Ln)O2 and Zn(Ln)S [Ln = Sm, Tb] nanoparticles to address the importance of the nanoparticle identity and absolute band gap in the underlying process. While the sensitization was evident in the Sn(Sm)O2 and Zn(Tb)S nanoparticles, the same was not observed in the Sn(Tb)O2 and Zn(Sm)S nanoparticles. This observation stresses the importance of nanoparticle identity as the determining factor in realizing the host-sensitized dopant photoluminescence and provides important insight into developing novel doped inorganic nanoparticle-based optical materials. © 2017 American Chemical Society.

PRASUN MUKHERJEE

GENERAL

P MANNA

A CHAKRABORTY

G H DEBNATH

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Journal of Physical Chemistry Letters

This work investigates the photoluminescence characteristics where cadmium selenide (CdSe) and zinc sulfide (ZnS) nanoparticles are treated post-synthetically by the trivalent lanthanide cations (Ln 3+ ) [Ln = Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb] separately to form either CdSe/Ln or ZnS/Ln nanoparticles. Host sensitized Ln 3+ emission was found to be present only in CdSe/Eu, CdSe/Tb, ZnS/Eu, ZnS/Tb and ZnS/Yb nanoparticles. In all the cases tuning of emission of the nanoparticles has been observed, irrespective of the presence or absence of host sensitization. The elemental compositions of CdSe and ZnS nanoparticles upon post-synthetic treatment show a remarkable difference. Incorporation of lanthanides in the nanoparticles is evident with significant alteration in the anionic content, and complete cation exchange of either Cd 2+ or Zn 2+ by Ln 3+ has not been detected; as evaluated from energy dispersive X-ray spectroscopy. Further evaluation on this comes from considering thermodynamic parameters of inter cation interaction. In cases where the host sensitized Ln 3+ emission have been observed, luminescence lifetime measurements reveal significant protection of Ln 3+ in the nanoparticles. Noticeable difference in photophysical properties for a given Ln 3+ has been realized in the two hosts. The photophysical observations have been rationalized using (i) charge trapping mediated host sensitized dopant emission, (ii) autoionization of excited electrons, and (iii) environment induced photoluminescence quenching. The post-synthetic modification discussed in the present work provides an easy and less synthetically demanding room temperature based protocol to avail lanthanide incorporated (doped) semiconductor nanoparticles that can potentially use the unique emission properties of the lanthanide cations. © 2019 Elsevier Inc.

Journal of Colloid and Interface Science

Host sensitized lanthanide photoluminescence from post-synthetically modified semiconductor nanoparticles depends on reactant identity

Lanthanide-incorporated semiconductor nanoparticle luminophores are attractive alternatives to conventional organic fluorophores for live-cell imaging due to their non-overlapping sharp emission bands, longer luminescence lifetimes and resistance to photobleaching. These materials provide avenues to use the unique luminescence properties of lanthanides, allowing the incorporation of multiple luminophores into the host matrix generating an enhanced emission, with additional benefits from the surface functionalization of the nanoparticles. Here, we report the first demonstration of host-sensitized samarium (Sm3+) emission, from (3-aminopropyl)trimethoxysilane (APTMS) functionalized Sm3+ doped titanium dioxide [Ti(Sm)O2] nanoparticles, and its usefulness as a live-cell imaging probe in human mammary adenocarcinoma (MDA-MB-231) and human embryonic kidney (HEK 293T) cell lines. Photoluminescence spectroscopic experiments with the lysates, obtained from cells treated with APTMS-Ti(Sm)O2 nanoparticles, displaying the host-sensitized sharp samarium (Sm3+) emission and the images acquired from both the bright field and emission channels in epifluorescence microscopy experiments of nanoparticle treated cells clearly indicate the interaction of the nanoparticles with the cells and their effectiveness as an imaging probe. Additionally, the non-cytotoxicity and photostability of this probe provide further benefits in the context of (i) increasing the probe concentration without compromising cellular viability and (ii) longer experimental times without encountering photobleaching, thus essentially improving the signal-to-noise ratio; challenges that are often associated with organic moiety based imaging probes. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2018.

New Journal of Chemistry

Host-sensitized sharp samarium emission from doped titanium dioxide nanoparticles as non-cytotoxic photostable reporters for live-cell imaging

Evaluation of inter dopant electronic interactions is important to maximize photoluminescence for their use as multiplex assays. This work compares the photophysical properties of lanthanide dopants in cases where the lanthanide moieties have been either synthetically co-doped in nanoparticles or two singly doped nanoparticles were physically mixed post-synthetically. Nd3+ − Sm3+ and Nd3+ − Er3+ were considered as dopants in the TiO2 nanoparticles. Remarkable differences in lanthanide emission have been observed between the two strategies of forming the multiple and distinct lanthanide containing assemblies. The inter lanthanide electronic interactions were found to be evident in the synthetic co-doping, with the same being absent in the physically mixed assembly. As a consequence, the Nd3+ emission in near infrared (NIR) and Sm3+, Er3+ emission in visible spectral range respectively have been found to be more pronounced in the physically mixed assembly as compared to that in the synthetically co-doped nanoparticles. The situation is however reversed for the Er3+ emission in NIR spectral range. These findings collectively provide a facile way to maximize dopant emission and indicate the importance of tuning the inter lanthanide electronic interactions for better suitability as multiplex agent, in an as-desired way. © 2018 Elsevier B.V.

Journal of Luminescence

Maximizing dopant photoluminescence in co-doped semiconductor nanoparticles for multiplex assays by tuning inter dopant electronic interactions: Synthetic co-doping or physical mixing of singly doped moieties?

This work reports the photophysical properties of 1-thioglycerol capped hydrophilic terbium cation incorporated (doped) zinc sulfide [Zn(Tb)S] nanoparticles, which have been post-synthetically modified using Pb2+ [Zn(Tb)S/Pb] under ambient conditions with [Zn(Tb)S]:[Pb2+] = 1:10-5-1:10, essentially providing a scenario with low to heavy co-doping and ultimately the possibility of forming a material of different chemical identity. The effects of selected concentrations of [Zn(Tb)S]:[Mn+] = 1:1 and 1:10-2 have also been evaluated for the post-synthetic addition of Hg2+, Cd2+, Ca2+, Mg2+, Na+ and K+. The broad zinc sulfide nanoparticle and sharp Tb3+ emission have different dependence on the relative reactant concentration, with cation identity playing a significant role. The underlying photophysical processes have been rationalized based on the interplay among the (i) cation exchange, (ii) modification of the structural properties of the nanoparticles without necessarily exchanging the cations and (iii) emission enhancement of terbium dopants. In cases where Tb3+ emission is apparent, all the nanoparticles studied demonstrate an optical antenna effect, thus accessing a lower Tb3+ concentration regime compared to in bulk environments. The results presented provide an avenue for the detection of heavy metal ions in general and Pb2+ in particular, with a limit of detection that is at least in the range of sub-ppm, using either the broad ZnS or sharp Tb3+ emission, respectively. This strategy provides an avenue to combine (i) the extremely sensitive and easily accessible analytical technique of photoluminescence spectroscopy, (ii) post-synthetic modification reactions in semiconductor nanoparticles that can be performed with less experimental demand, (iii) time-gated measurement related to the longer luminescence lifetime of terbium cations and (iv) the simultaneous use of broad ZnS nanoparticle and sharp Tb3+ emission from the same assembly, helping eliminate false positive results. © The Royal Society of Chemistry 2018.

Fulltext

RSC Advances

Role of reactant concentration and identity of added cation in controlling emission from post-synthetically modified terbium incorporated zinc sulfide nanoparticles: An avenue for the detection of lead(ii) cations

A systematic comparison of the Ln3+ [Ln = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb] photoluminescence in doped tin dioxide [Sn(Ln)O2] and doped titanium dioxide [Ti(Ln)O2] nanoparticles shows that the emission efficiency of trivalent lanthanide cations (Ln3+) in an oxide matrix can be improved by change of the cation site symmetry. An analysis of Ln3+ emission quantum yield and asymmetry ratio is used to identify the importance of symmetry breaking around the dopant site for enhancing the Ln3+ emission intensity. These findings identify an important criterion for engineering the luminescence intensity of dopant ions in semiconductor nanoparticle-based luminophores, which goes beyond the primary criterion of engineering the relative positions of the dopant energy levels with respect to the band edges of the host nanoparticle matrix. Copyright © 2018 American Chemical Society.

What Is beyond Charge Trapping in Semiconductor Nanoparticle Sensitized Dopant Photoluminescence?

This work reports on the realization of luminescence from four visible emitting trivalent lanthanide (Ln) cations [samarium (Sm), europium (Eu), terbium (Tb) and dysprosium (Dy)] in polar zinc sulfide nanoparticles, Zn(Ln)S. Among the Zn(Ln)S nanoparticles studied, noticeable lanthanide cation centered luminescence has only been realized from the Zn(Tb)S and Zn(Eu)S nanoparticles in water, whereas no such effect has been observed in the corresponding Sm and Dy containing nanoparticles. In all the nanoparticles with characteristic lanthanide luminescence, the nanoparticles were found to be acting as an optical antenna and protector matrix, in order to realize luminescence from the respective lanthanide cations. The results have been rationalized with the lanthanide cations acting as charge (hole and/or electron) traps in the semiconductor nanoparticle matrix along with associated environmental effects. A comparison of the corresponding hydrophobic Zn(Tb)S nanoparticles reveal significant differences in photophysical properties. Finally, the hydrophilic Zn(Tb)S nanoparticles have been examined for in vitro cytotoxicity and the results indicate potential anti-cancer therapy for human mammary adenocarcinoma cells (MDA-MB-231) with the capability of cellular imaging. © The Royal Society of Chemistry 2016.

Towards the realization of luminescence from visible emitting trivalent lanthanides (Sm, Eu, Tb, Dy) in polar zinc sulfide nanoparticles: Evaluation of: In vitro cytotoxicity

This work develops a rationale for effective sensitization of trivalent lanthanide cation (Ln3+) luminescence in a semiconductor nanoparticle by examining the luminescence characteristics of Ln3+ dopants in titanium dioxide nanoparticles [Ti(Ln)O2] [Ln = praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), or ytterbium (Yb)], as a representative model system. For excitation of the TiO2 host at 350 nm the intraconfigurational 4f-4f sharp luminescence bands are observed for the Nd, Sm, Eu, Ho, Er, Tm, and Yb incorporated (doped) nanoparticles, and no such luminescence is observed for the Pr, Gd, Tb, and Dy containing nanoparticles. While host sensitized luminescence of lanthanide ions dominate the emission in the Nd and Sm incorporated nanoparticles, the host sensitization effect is less pronounced for the Eu and Yb containing systems, and for the Ho, Er, and Tm doped nanocrystals only a subset of the dopant ions' luminescence bands is sensitized. The experimental observations of the host sensitized Ln3+ luminescence properties in the [Ti(Ln)O2] nanoparticles can be rationalized by considering that the dopant ions act as charge traps in the host lattice and associated environment induced luminescence quenching effects. Using these results, an energy offset between the trap site and the nanoparticle's band edge that will generate an optimal host sensitized dopant emission is proposed. The approach presented necessarily improves over a combinatorial approach to select the host and dopant moieties, with the benefit of providing physicochemical insight regarding the nature of photophysical processes in a given host (semiconductor nanoparticle)-guest (Ln3+) composite system. © 2016 American Chemical Society.

Journal of Physical Chemistry C

Identifying the Correct Host-Guest Combination to Sensitize Trivalent Lanthanide (Guest) Luminescence: Titanium Dioxide Nanoparticles as a Model Host System

The lanthanide photoluminescence in the trivalent terbium (Tb3+) incorporated zinc sulfide nanoparticles [Zn(Tb)S] has been reported with the nanoparticle size varying from 2.0 ± 0.3 to 14 ± 3 nm in diameter as a function of reaction temperature. In all the nanoparticles, the Tb3+ luminescence has been sensitized by the nanoparticle acting as an optical antenna. The relative contribution of different excitation bands in sensitizing Tb3+ luminescence in the Zn(Tb)S nanoparticles has been found to be dependent on the size of the nanoparticles. The observed Tb3+ luminescence efficiency in the Zn(Tb)S nanoparticles has been rationalized by competing factors: (i) the sensitization efficiency that is guided by the relative energy level position of the Tb3+ ground and excited states with respect to the valence and conduction bands of the ZnS and (ii) the extent of incorporation of Tb3+ in the nanoparticles. Additionally, it has been argued that the spectral overlap between the nanoparticle (donor) emission and Tb3+ (acceptor) absorption is not a prerequisite in determining the Tb3+ emission in the Zn(Tb)S nanoparticles studied. © 2015 American Chemical Society.

Journal	Data powered by TypesetJournal of Physical Chemistry Letters
Publisher	Data powered by TypesetAmerican Chemical Society
ISSN	1948-7185
Open Access	No