Bleach Recovery Research Articles

Nonlinear optical properties of MXene and applications in broadband ultrafast photonics

As a typical kind of two-dimensional transition metal carbides, nitrides and/or carbonitrides (MXene), Ti 3 C 2 T x has attracted extensive attention in optoelectronic field owing to their outstanding thermal, optoelectronic, and nonlinear optical properties. Ti 3 C 2 T x has been widely used as saturable absorber (SA) for achieving ultrafast pulses, whereas the influence of recovery time on its nonlinear optical properties as SA in laser needs further exploration. Herein, the ultrafast dynamics and nonlinear optical properties of Ti 3 C 2 T x are investigated by the methods of transient absorption and balanced twin-detector measurements. According to the experimental results, Ti 3 C 2 T x has a bleaching recovery time more than 160 ps, resulting in a low saturation intensity. The prepared Ti 3 C 2 T x is utilized as SA to achieve Q-switched pulses at 1- and 1.5- μ m bands. This study demonstrates that ultrafast dynamics has a significant impact on adjusting and optimizing nonlinear optical parameters of MXenes, as well as designing new photonic devices. • Optical properties and applications of Ti 3 C 2 T x as saturable absorber (SA) in 1- and 1.5- μ m lasers were studied. • Effect of carrier dynamics of Ti 3 C 2 T x on saturable absorption performance was discussed. • Ti 3 C 2 T x as SA in lasers was quantitatively analyzed, benefiting for realizing customized SA. • Large-energy Q-switched pulses were realized in 1- and 1.5- μ m bands owing to low saturable intensity.

The Effect of Temperature on Goniastrea aspera Polyp Degradation and the Post-bleaching Resistance

Coral recovery from bleaching depends not only on the intensity and continuity of some influencing factorsbut also on the cellular condition of the coral itself. The relationship between coral recovery and bleachingcan be studied from the loss process of zooxanthellae from a polyp and the tissue profile changes. Thisresearch focused on the degradation of polyp tissue due to temperature stressors and the potential recoveryafter bleaching in artificial media. It was conducted at Coastal Eco-development Laboratory of FPIK-UNDIPJepara and natural waters of coral reef ecosystem in Southern of Panjang Island Jeparafrom April toSeptember 2021. Four levels of temperature: 40oC, 36oC, 32 oC 28 oC were used to expose the sample organisms.The objectives of this research are, therefore, to (a)investigate the effect of temperature on the zooxanthellaedensity in the polyp tissues, (b) investigate the effect of temperature on process change of polyp tissues and(c) analyze the survivability of coral after bleaching. The results show that: (a) the optimum temperatureand exposure that zooxanthellae can resist in the polyp histology of Goniastrea aspera is 36 oC for 6 hours, (b)Higher temperature and longer incubation time degrade the tissue of the Goniastrea asperapolyp, influencethe zooxanthellae release and cause coral death, (c) The recovery of the Goniastrea aspera still occurs afterpartial bleaching and (d) Coral recovery is characterized by the zooxanthellae regulation process in thepolyp tissues and reaches perfect condition and to achieve perfect arrangement after week 12.

Towards the scale-up of solid-state, low-emissive electrochromic films, fabricated on a single substrate with novel electrolyte formulations

This experimental work reports the activities of design, fabrication and characterization of an innovative solid-state electrochromic device, deposited on a single substrate with high transparency in the bleached conditions and a wide modulation of transmittance (ΔT of 60% at 750 nm) both in the visible and near-infrared wavelengths. A tailored formulation of the solid electrolytes, based on sulfonated tetrafluoroethylene-based fluoropolymer-copolymer dispersions and the accurate design of a suitable layer of porous tin oxide nanoparticles provided high coloration and bleaching kinetics and recovery of the pristine conditions, even after 500 complete cycles. Devices were scaled-up to 10 × 10 cm2 size, without mechanical and aesthetic defects and relevant homogeneity, throughout the coloration and bleaching processes. Furthermore, this device shows the further feature to be a low-emissivity dynamic solar control film, highly compatible with integration within insulated glazed units.

Leveraging Dynamical Symmetries in Two-Dimensional Electronic Spectra to Extract Population Transfer Pathways.

We present a method to deterministically isolate population transfer kinetics from two-dimensional electronic spectroscopic signals. Central to this analysis is the characterization of how all possible subensembles of excited state systems evolve through the population time. When these dynamics are diagrammatically mapped by using double-sided Feynman pathways where population time dynamics are included, a useful symmetry emerges between excited state absorption and ground state bleach recovery dynamics of diagonal and below diagonal cross-peak signals. This symmetry allows removal of pathways from the spectra to isolate signals that evolve according to energy transfer kinetics. We describe a regression procedure to fit to energy transfer time constants and characterize the accuracy of the method in a variety of complex excited state systems using simulated two-dimensional spectra. Our results show that the method is robust for extracting ultrafast energy transfer in multistate excitonic systems, systems containing dark states that affect the signal kinetics, and systems with interfering vibrational relaxation pathways. This procedure can be used to accurately extract energy transfer kinetics from a wide variety of condensed phase systems.

Ultrafast carrier dynamics in CdS@CdSe core-shell quantum dot heterostructure

Semiconductor quantum dots (QDs) have aroused great fundamental and technological interest due to their novel size-tunable optical properties, and the resulting potential applications in photonics, photoelectronics and biomedicine. In this study, uniform, ultrasmall, well-defined CdS@CdSe core-shell QDs are successfully synthesized by a hot injection method for ultrafast carrier dynamics activities. Femtosecond transient absorption studies show that the bleach recovery time of the CdS@CdSe QDs increases with the thickness of the CdSe shell. In addition, theoretical calculations were carried out to reveal this characteristic. The slower carrier relaxation of the CdS@CdSe QDs indicates its great potential applications from light-emitting diodes to photodetectors and photovoltaics. In short, this work provides a valuable reference platform for the application of core-shell QD-based heterostructure in optics and optoelectronics.

Elevated temperature alters bacterial community composition and metabolism in seawaters of coral reef ecosystem: An evidence of laboratory experiment with Acropora digitifera bleaching

The global phenomenon of coral bleaching under thermal stress has been recognized as the primary driver underlying coral reef degradation. The coral bacterial community plays an important role in the stability of coral reef ecosystem. Dimethylsulfoniopropionate (DMSP) and its associated metabolites are essential for the establishment of coral bacterial communities and provide key benefits for overall coral health and bleaching recovery. Substantial research to date has focused on the bacterial community composition, metabolism and functional properties within the coral holobiont, but less attention has been paid to the role of bacteria in seawater surrounding corals under thermal stress. Here, we investigated bacterial community composition, biological functions and DMSP metabolism changes of the seawater surrounding corals under thermal stress. We found that microbial community in seawater surrounding corals changed under thermal stress, and corals bleached eventually. The abundance of Rhodobacterales, Flavobacteriales and Rhizobiales increased while Chitinophagales and SAR11 decreased as temperature elevated. Correspondingly, stress tolerant, biofilm forming and mobile elements increased, resulting in large part from changes in Rhodobacterales and Phaeodactylibacter abundance. DMSP producing and catabolic levels in seawater surrounding corals were enhanced under thermal stress with higher dsyB (1.46-fold), dddP (2.43-fold) and dmdA (1.47-fold) detected. This study reveals the biological functions and metabolisms of bacteria in the water surrounding corals, providing valuable insight on how these communities and functions change in coral reef ecosystem under thermal stress.

Ingestion of Diazotrophs Makes Corals More Resistant to Heat Stress.

Over the past decade, coral bleaching events have continued to recur and intensify. During bleaching, corals expel millions of their symbionts, depriving the host from its main food source. One mechanism used by corals to resist bleaching consists in exploiting food sources other than autotrophy. Among the food sources available in the reefs, dinitrogen (N2)-fixing prokaryotes or planktonic diazotrophs (hereafter called ‘PD’) have the particularity to reduce atmospheric dinitrogen (N2) and release part of this nitrogen (diazotroph-derived nitrogen or DDN) in bioavailable form. Here, we submitted coral colonies of Stylophora pistillata, fed or not with planktonic diazotrophs, to a temperature stress of up to 31 ± 0.5 °C and measured their physiological responses (photosynthetic efficiency, symbiont density, and growth rates). Heat-unfed colonies died 8 days after the heat stress while heat-PD-fed corals remained alive after 10 days of heat stress. The supply of PD allowed corals to maintain minimal chlorophyll concentration and symbiont density, sustaining photosynthetic efficiency and stimulating coral growth of up to 48% compared to unfed ones. By providing an alternative source of bioavailable nitrogen and carbon, this specific planktonic diazotroph feeding may have a profound potential for coral bleaching recovery.

The role of the endolithic alga Ostreobium spp. during coral bleaching recovery

In this study, we explore how the Caribbean coral Orbicella faveolata recovers after bleaching, using fragments from 13 coral colonies exposed to heat stress (32 °C) for ten days. Biological parameters and coral optical properties were monitored during and after the stress. Increases in both, the excitation pressure over photosystem II (Qm) and pigment specific absorption (a*Chla) were observed in the stressed corals, associated with reductions in light absorption at the chlorophyll a red peak (De675) and symbiont population density. All coral fragments exposed to heat stress bleached but a fraction of the stressed corals recovered after removing the stress, as indicated by the reductions in Qm and increases in De675 and the symbiont population observed. This subsample of the experimentally bleached corals also showed blooms of the endolithic algae Ostreobium spp. underneath the tissue. Using a numerical model, we quantified the amount of incident light reflected by the coral, and absorbed by the different pigmented components: symbionts, host-tissue and Ostreobium spp. Our study supports the key contribution of Ostreobium spp. blooms near the skeletal surface, to coral recovery after bleaching by reducing skeleton reflectance. Endolithic blooms can thus significantly alleviate the high light stress that affects the remaining symbionts during the stress or when the coral has achieved the bleached phenotype.

Natural Variability in Caribbean Coral Physiology and Implications for Coral Bleaching Resilience

Coral reefs are among the most diverse and complex ecosystems in the world that provide important ecological and economical services. Increases in sea surface temperature linked to global climate change threatens these ecosystems by inducing coral bleaching. However, it is not fully known if natural intra- or inter-annual physiological variability is linked to bleaching resilience or recovery capacity of corals. Here, we monitored the coral physiology of three common Caribbean species (Porites divaricata, Porites astreoides, Orbicella faveolata) at six time points over 2 years by measuring the following traits: calcification, biomass, lipids, proteins, carbohydrates, chlorophyll a, algal endosymbiont density, stable carbon isotopes of the host and endosymbiotic algae, and the stable carbon and oxygen isotopes of the skeleton. The overall physiological profile of all three species varied over time and that of P. divaricata was consistently different from the two other coral species. Porites divaricata had higher energy reserves coupled with higher contributions of heterotrophically derived carbon to host tissues than both P. astreoides and O. faveolata. Consistently higher overall energy reserves and heterotrophic contributions to tissues appear to buffer against environmental stress, including bleaching events. Thus, natural physiological variability among coral species appears to be a stronger predictor of coral bleaching resilience than intra- or inter-annual physiological variability within a coral species.

Evidence of auger heating in hot carrier cooling of CsPbBr3 nanocrystals

Hot Carrier (HC) Dynamics in Lead halide perovskites shows a unique hindered hot carrier cooling. In the present study, we use femtosecond transient absorption technique to interrogate CsPbBr3 to study the role of different carrier cooling mechanisms in HC cooling process. This is accomplished here by considering fitting of the high-energy region of photoinduced bleach with a Fermi-Dirac distribution instead of Maxwell-Boltzmann Distribution. This approach reveals important time dependent parameters like quasi fermi level, apart from carrier temperature. Under low carrier densities with N < <1, the dynamics revealed bleach recovery in time scales > 1 ns revealing dynamics is governed by electron-hole radiative recombination. The HC cooling dynamics under low carrier density (2 *1017/cm3) revealed the cooling is predominantly dominated by short lifetime component of ~0.26 ps. This time is significantly elongated as compared to lifetime of longitudinal optic (LO) phonon lifetime in perovskites, clearly indicative of Froehlich interaction in play along with large polaron formation. However, under higher carrier densities > 1018/cm3, additional lifetime component contributes to HC cooling with a time constant of ~17 ps. This time constant could be assigned to Auger heating. The role of LO phonon filling and Auger heating was ascertained also on the basis energy loss rate vs carrier temperature fitting with these individual cooling models. To ascertain the role of Auger heating we also used different sized samples which showed the scaling of Auger heating times in agreement with size dependent Auger recombination times as reported in the literature. Such long HC cooling opens avenues to possibly extract hot carriers before cooling leading to development of HC photovoltaics.

Atomlike interaction and optically tunable giant band-gap renormalization in large-area atomically thin MoS2

Coulomb interactions in atomically thin transition metal dichalcogenides can be dynamically engineered by exploiting the dielectric environment to control the optical and electronic properties. Here we demonstrate an optically tunable giant band-gap renormalization (BGR) $\ensuremath{\sim}1200$ and 850 meV from the edge of the conduction band and complete suppression of the exciton absorption in large-area single-layer (1L) and three-layer (3L) ${\mathrm{MoS}}_{2}$, respectively. The observed giant BGR is two orders of magnitude larger than that in the conventional semiconductors, and it persists for tens of ps. Strikingly, our results demonstrate photoinduced transparency at the electronic band gap using an intense optical field at room temperature. Exciton bleach recovery in 1L and 3L show a contrasting fluence-dependent response, demonstrating the layer-dependent optical tuning of exciton lifetime in a way that would be both reversible and real time. We find that the optical band gap (exciton resonance peak) shows a transient redshift followed by an anomalous blueshift from the lowest energy point as a function of the photo-generated carrier density. The observed exciton energy shift is analogous to atom-atom interactions, and it varies as a Lennard-Jones like potential as a function of the interexciton separation.

Synergistic dynamics of photoionization and photoinduced electron transfer probed by laser flash photolysis and ultrafast fluorescence spectroscopy.

Photoionization (PI) and photoinduced electron transfer (PET) dynamics of coumarin 450 (C450) in micelles were investigated in the time domains of micro to femtoseconds using steady-state and time-resolved absorption and fluorescence spectroscopy. The PI of C450 occurs inside the micelles leads to the formation of C450 cation radical (CR) and hydrated electron, which is characterized by the respective transient absorption. The PI of C450 is monophotonic in nature and the yield is dependent on the charge of the micelles. The observation of amine CR in the transient absorption confirms the PET from amine to the excited state of C450 in micelles, which results in the quenching of both fluorescence intensity and lifetime. The decrease in femtosecond fluorescent decay of C450 and the absence of transient C450 radical anion in the presence of amine implies that the concerted ultrafast PET promoted PI and PET to the C450 CR-electron pair. The decrease in the time constant for the formation of relaxed state in the presence of amines is due to the ultrafast PET to the C450 CR-electron pair, which prevents the formation of a relaxed state through recombination at a longer time scale. In the present investigation, the recombination dynamics of the CR-electron pair is justified as one of the origins of the slow solvation in micelles. The influence of amine concentration on the decay of C450 CR indicates ET reaction between C450 CR and amine, which is further confirmed by the bleach recovery of C450 ground state in the presence of amine.

Reconnecting reef recovery in a world of coral bleaching

AbstractCoral bleaching can have widespread impacts on reefs leaving many areas in need of coral recovery. While the long‐term mitigation of bleaching requires transitioning to a low carbon economy, local management has focused on approaches that seek refugia from or tolerance to bleaching stressors, reduce additional stressors, or facilitate coral recovery. Here, we describe a tactical response to coral bleaching events that seeks to identify the most important reefs for driving imminent recovery. A bleaching recovery algorithm is described that identifies those reefs that provide the most important sources of coral larvae that supply many reefs in the early stages of post‐bleaching recovery (i.e., reefs in need of coral larval supply). We describe the algorithm with a simple toy example and then apply it to the Great Barrier Reef, which has experienced three mass bleaching events in the last 5 yr. Once such reefs have been identified it makes practical sense to undertake a vulnerability assessment and if necessary reduce manageable stressors, such as outbreaks of crown‐of‐thorns starfish or anchor damage, so that critical sources of coral recovery are not depleted further. In short, algorithms like this can help managers target finite management resources, including restoration, to where they might be most effective in facilitating natural processes of recovery.

Auger Dynamics in InP/ZnSe/ZnS Quantum Dots Having Pure and Doped Shells

In this study, we report the negative trion and biexciton Auger dynamics in very high-quality InP/ZnSe/ZnS quantum dots (QDs) having varying amounts of indium-based traps in the ZnSe shell. Negative trion times are determined by time-correlated photon-counting measurements on QDs that have been photoreduced with lithium triethylborohydride. We find that the Auger times vary from 280 to 425 ps and scale linearly with the total particle volume. Excess indium in the ZnSe shell gives rise to hole traps that are transiently populated following photoexcitation. Comparing stoichiometric and nonstoichiometric particles, we find that the negative trion lifetimes are independent of the presence of indium in the ZnSe shell. Biexciton dynamics are determined from transient absorption (TA) bleach recovery measurements. Absorption of two photons results in the formation of two types of biexcitons: those having both holes in the InP core (XX state) and those having one hole trapped in the ZnSe shell (XT state). XX state Auger times are measured in stoichiometric QDs, and for these particles, the Auger times are ∼80 ps. Nonstoichiometric QDs show an additional long TA decay component, assigned to Auger recombination of the XT state. A previous study (J. Phys. Chem. C2021, 125, 4110–4118) found that hole trapping at indium-based shell traps results in a slow photoluminescence (PL) rise component. We find that the fraction of the XT state formed by the absorption of two photon correlates with the product of the fraction of slow PL rise and the rise time constant following one-photon excitation.

Microbiomes of Healthy and Bleached Corals During a 2016 Thermal Bleaching Event in the Upper Gulf of Thailand

Global warming has caused elevated seawater temperature and coral bleaching, including events on shallow reefs in the upper Gulf of Thailand (uGoT). Previous studies have reported an association between loss of zooxanthellae and coral bleaching. However, studies on the microbial diversity of prokaryotes and eukaryotes (microbiome) as coral holobionts are also important and this information is still limited in the uGoT. To address this shortcoming, this report provided baseline information on the prokaryotic (bacteria and archaea) and eukaryotic microbes of healthy and bleached colonies of four prevalent corals Acropora humilis, Acropora millepora, Platygyra sinensis, and Porites lutea and surrounding seawater and sediments, using 16S and 18S rRNA gene next-generation sequencing. Both prokaryotic and eukaryotic microbes showed isolated community profiles among sample types (corals, sediment, and seawater) (ANOSIM: P &amp;lt; 0.001, R = 0.51 for prokaryotic profiles and P &amp;lt; 0.001, R = 0.985 for eukaryotic microbe profiles). Among coral species, P. sinensis showed the most diverse prokaryotic community compared with the others (ANOSIM: P &amp;lt; 0.001, R = 0.636), and P. lutea showed the most diverse eukaryotic microbes (P = 0.014, R = 0.346). Healthy and bleached corals had some different microbiomes in species and their prevalences. For instance, the significant increase of Alphaproteobacteria in P. sinensis resulted in reduced prokaryotic community evenness and altered potential metabolic profiles (i.e., increased amino acid metabolism and genetic information processing and transcription, but decreased prokaryotic functions in cell motility, signaling, and transduction). For eukaryotic microbes, the loss of the algal Symbiodinium (colloquially known as zooxanthellae) in bleached corals such as P. lutea resulted in increased Chromista and Protista and, hence, clearly distinct eukaryotic microbe (including fungi) communities in healthy vs. bleached colonies of corals. Bleached corals were enriched in bacterial pathogens (e.g., Acinetobacter, Helicobacter, Malassesia, and Aspergillus) and decreased coral-beneficial prokaryotic and eukaryotic microbes (e.g., Rhizobiales and Symbiodinium). Additionally, this study identified microbiome species in bleached P. lutea that might help bleaching recovery (e.g., high abundance of Rhizobiales, Oceanospirillales, Flavobacteriales, and Alteromonadales). Overall, our coral-associated microbiome analyses identified altered diversity patterns of bacteria, archaea, fungi, and eukaryotic microbes between healthy and bleached coral species that are prevalent in the uGoT. This knowledge supports our ongoing efforts to manipulate microbial diversity as a means of reducing the negative impacts of thermal bleaching events in corals inhabiting the uGoT.

Ultrafast spectroscopic investigation of discrete co-assemblies of a Zn-porphyrin–polymer conjugate with a hexapyridyl template

One of the key features of biological light harvesting complexes (LHCs) is their incorporation of multi-chromophoric reaction centres via non-covalent interactions. Most synthetic mimics require relatively complex syntheses and are constructed in organic solvents. Here, we report the use of polymer self-assembly to enable the formation of Zn-porphyrin–pyridine complexes in aqueous solution. Time-resolved femtosecond pump–probe spectroscopy revealed four time constants, each associated with significant ground state bleach recovery, suggesting energy transfer between the porphyrin and pyridine. Self-assembly opens up new photophysical relaxation pathways, making it a useful additional strategy for the construction of more advanced LHC mimics.

Going with the flow: How corals in high-flow environments can beat the heat.

Coral reefs are experiencing unprecedented declines in health on a global scale leading to severe reductions in coral cover. One major cause of this decline is increasing sea surface temperature. However, conspecific colonies separated by even small spatial distances appear to show varying responses to this global stressor. One factor contributing to differential responses to heat stress is variability in the coral's micro-environment, such as the amount of water flow a coral experiences. High flow provides corals with a variety of health benefits, including heat stress mitigation. Here, we investigate how water flow affects coral gene expression and provides resilience to increasing temperatures. We examined host and photosymbiont gene expression of Acropora cf. pulchra colonies in discrete in situ flow environments during a natural bleaching event. In addition, we conducted controlled ex situ tank experiments where we exposed A. cf. pulchra to different flow regimes and acute heat stress. Notably, we observed distinct flow-driven transcriptomic signatures related to energy expenditure, growth, heterotrophy and a healthy coral host-photosymbiont relationship. We also observed disparate transcriptomic responses during bleaching recovery between the high- and low-flow sites. Additionally, corals exposed to high flow showed "frontloading" of specific heat-stress-related genes such as heat shock proteins, antioxidant enzymes, genes involved in apoptosis regulation, innate immunity and cell adhesion. We posit that frontloading is a result of increased oxidative metabolism generated by the increased water movement. Gene frontloading may at least partially explain the observation that colonies in high-flow environments show higher survival and/or faster recovery in response to bleaching events.

Unusual Hole Transfer Dynamics of the NiO Layer in Methylammonium Lead Tri-iodide Absorber Solar Cells.

Nickel oxides (NiO) as hole transport layers (HTLs) in inverted-type perovskite solar cells (PSCs) have been widely studied mainly because of their high stability under illumination. Increases in the power conversion efficiency (PCE) with NiO HTLs have been presented in numerous reports, although the photoluminescence (PL) quenching behavior does not coincide with the PCE increase. The dynamics of the charge carrier transport between the NiO HTLs and the organic-inorganic halide perovskite absorbers is not clearly understood yet and quite unusual, in contrast to organic/polymerics HTLs. We deposited NiO HTLs with precisely controlled thicknesses by atomic layer deposition (ALD) and studied their photovoltaic performances and hole transfer characteristics. Ground state bleaching (GSB) recovery was observed by ultrafast transient absorption spectroscopy (TAS), which suggested that backward hole injection occurred between the perovskites and NiO HTLs, so that the uncommon PL behaviors can be clearly explained. Backward hole injection from the NiO HTL to the perovskite absorber originated from their similar valence band (VB) energy positions. The thickness increase of the NiO HTLs induced VB sharing, which caused a red-shift of the photoinduced hole absorption spectrum in near-infrared (NIR) femtosecond TAS and a decrease in the PL intensity. Our studies on inorganic metal oxide transport layers, NiO in this work, with a thickness dependence and the comparison with organic layers provide a better understanding of the interfacial carrier dynamics in PSCs.

Processes and problems of pulp and paper industry: an overview

Abstract The pulp and paper industry is a highly energy-intensive and water-consuming industry. This industry is known for the utilization of a wide range of raw materials, containing cellulose fibers (generally wood, recycled paper, and agricultural residues), for the production of various grades of paper. There are several processes involved in the conversion of raw materials to the paper product such as raw material preparation, pulping, pulp washing and screening, bleaching, stock preparation, papermaking and chemical recovery. All the processes are facing issues regarding process efficiency, product quality, energy &amp; water consumption, and cost and environment. There is a need for further improvement and upgrading the technologies but the scale of operations, technological obsolesce and cost of implementing new technologies are some of the major issues. The main thrust areas of pulp and paper processing require major interventions in the adoption of green and clean technologies.

Release of Warfarin from Human Serum Albumin by Water‐soluble CdSe Nanotetrapods

Water soluble CdSe nanotetrapods are prepared by ligand exchange from organic-soluble ones. In order to achieve this, oleic acid, which is the capping agent for as prepared water-insoluble nanotetrapods, is exchanged with mercaptopropanoic acid (MPA). Shape and size of nanotetrapods are conserved upon ligand exchange. Ground state bleach recovery dynamics remain the same as well. However, they are completely non-emissive. These water-soluble nanotetrapods disrupt the secondary structure of Human Serum Albumin (HSA) and consequently, release warfarin bound to the protein.