Maximum Absorption Wavelength Research Articles

Oxidation of glyoxal with the Mo-oxime complex in a benzalkonium chloride interface: Raghavan and Srinivasan kinetic model

Gaining an understanding of the glucose oxidation product (glyoxal) interaction with the metal–organic complex in a biological environment is pivotal to its usage. Thus, the glyoxal (Gyx) oxidation with Mo-oxime complex (MC) is studied with the spectrophotometric method, following a pseudo-phase approach. The result highlights the inclusion of hydrolysis, ion catalysis, the neutral primary salt effect, and radical generation as the essential factors in Gyx oxidation, with the exclusion of intermediate species formation. The hydrolysis of Gxy is observed to actively engage MC without charge inhibition as charge-neutral reacting species are involved, thus, implicating neutral primary salt effect where the variation of ionic strength of the system keeps the redox rate unchanged. The involvement of charge-neutral specie at the rate controlling step encouraged electrostatic attraction when Mg2+ ion additive is incorporated into the system, leading to ion catalysis. The generation of free radical from Gxy aids the emergence of formic acid. The zero intercept of Michealis-Menten type plot and the non-appreciable shift in the maximum absorption wavelength of the reaction system and MC rule-out the presence of intermediate species. The contribution of thermodynamic enthalpy is instrumental in the redox process, leading to the formic acid product. The inclusion of benzalkonium chloride (BZC) hastens the Gxy oxidation, which is supported by Raghavan and Srinivasan’s model.

Comprehensive analysis of dye adsorption and supramolecular interaction between dyes and cotton fibers in non-aqueous media/less water dyeing system

Cotton textile dyeing consumes large amounts of energy and water and discharges large amount of wastewater and pollutants. Zero or less discharge of the wastewater and contaminants from the cotton textile dyeing has been under high demands from textile industry. Recently, a novel reactive dyeing technology of using a non-aqueous medium with little water (NMLW) was developed for cotton fabrics. However, the use of high concentration of reactive dyes in the system triggers aggregation of the dyes in cotton fibers, influencing the quality of dyed cotton textiles. In this investigation, adsorption, diffusion, and aggregation behavior of reactive dyes in cotton fibers were studied. Compared to traditional water-based dyeing system, cotton fabrics demonstrated superior color depth, as long with higher rates of dye uptake and fixation for reactive dyes. At low dye concentrations, the maximum absorption wavelengths of reactive dyes were unchanged, and complied with the Lambot-Beer law. However, when the dye concentration was excessively high, reactive dyes with different molecular structures, as well as multi-layer dye aggregates with π-π stacking and hydrogen bonding interactions, showed different light absorption spectral characteristics and photophysical properties. Moreover, the dye particle size and dye ionization were influenced by the dye concentration, molecular weight, molecular configuration, etc. Analysis of the molecular dynamics of reactive dyes revealed that the maximum dye aggregation size was predominantly dimer at low dye concentration. However, the dimer ratio significantly decreased, while the trimer ratio increased, and higher-order aggregates were observed at a higher dye concentration. The strength of hydrogen bonds between dye molecules and water molecules, as well as the number of water molecules surrounding dye molecules, was influenced by dye concentration and alkali. This study provides a foundation for understanding the micro-aggregation behavior of reactive dyes and offer guidance for optimizing the dyeing process in practical production settings.

PHYSICOCHEMICAL AND SPECTROSCOPIC ANALYSIS OF INTERACTIONS BETWEEN ASPIRIN AND NORMAL SALINE AT DIFFERENT TEMPERATURES

The primary goal of the current investigation is to explore the molecular interactions between the aspirin (2-Acetoxybenzoic acid) and normal saline (0.9% w/v aqueous NaCl) at various concentrations (0.001–0.010) m and temperature (T= 300.15–315.15) K. To understand the various possible molecular interactions, volumetric, acoustic, conductometric and viscometric parameters were evaluated using experimental measured values of densities (ρ), ultrasonic velocities (u), specific conductance (κ), and viscosities (η). The results derived from these parameters have been examined in terms of drug–solvent and drug-drug interactions. The results of physicochemical studies indicate that aspirin exhibits strong interactional and structure–forming behaviour in normal saline. These results were well supported by UV-visible spectral studies which indicate the existence of intense aspirin–normal saline interactions in the form of modification in absorption maximum and absorption wavelength. The cyclic voltammetric studies were also performed to explore the oxidation/reduction behaviour and effect of aspirin on hemolysis. The experimental analysis of these studies provides valuable insights for better drug design, drug delivery, compatibility, potential safety, and biological relevance for the pharmaceutical and health industries.

A convenient approach for generating dimeric nucleic acid dyes via click-chemistry

Fluorescent dyes are essential tools for visualizing DNA and RNA. Dimeric dyes like GelGreen have gained popularity as safer alternatives to ethidium bromide (EB) due to their reduced mutagenicity and genotoxicity. In this study, we present a straightforward method to synthesize novel acridine orange (AO)-based dimeric dyes using click chemistry. Starting from acridine orange, these dyes can be synthesized in just two steps. Compared to GelGreen, these new dyes incorporate additional triazole groups in their linkers. They exhibit a maximum absorption wavelength of approximately 472 nm, which shifts to around 503 nm upon binding with DNA, allowing excitation by blue light. These dyes show minimal fluorescence in aqueous solutions, indicating that they adopt a closed conformation where the fluorescence of acridine orange is quenched due to intramolecular aggregation. The presence of DNA significantly enhances their fluorescence at around 526 nm, suggesting that DNA binding induces an open conformation. This “light-up” property makes them highly sensitive DNA dyes with a strong signal-to-noise ratio. We successfully applied these novel dyes in agarose gel electrophoresis, where they demonstrated excellent performance.

Computational Assessment of Novel Ruthenium Phenoxazine‐Based Complexes as Photosensitizers in Photodynamic Therapy

AbstractA computational examination of two new polypyridyl ruthenium complexes, containing meldola blue (MDB) and nile blue (NB) chromophores, is here reported in order to assess the applicability of phenoxazine‐containing complexes in photodynamic therapy (PDT). The designed complexes, named Ru‐3ENB and Ru‐3EMDB, are based on a recently synthesized Ru(II)‐based complex bearing a bipyridyl‐ethynyl‐Nile Red (NR) ligand and proposed for PDT applications. DFT outcomes elucidated how the replacement of NR with MDB induces a red shift of the maximum absorption wavelength within the therapeutic window, up to 638 nm. A change in the molecular orbitals involved in the population of excited states was observed upon chromophore substitution that results in ISC kinetic significantly faster than that computed for the synthesized complex Ru‐3ENR.

Analysis of sildenafil citrate in male stamina herbal medicines from the Magelang region, Central Java using thin-layer chromatography and UV spectrophotometry

Background: Male stamina herbal medicines are widely consumed in Indonesia, often believed to enhance sexual performance. However, the illegal addition of medicinal chemicals (BKOs) such as sildenafil citrate in traditional herbal products poses health risks. Objective: To identify and quantify sildenafil citrate in selected herbal medicine samples using thin-layer chromatography (TLC) and UV spectrophotometry. Method: Three samples of male stamina herbal medicine were purchased and subjected to organoleptic tests. Ethanol (96%) was used for extraction, followed by TLC analysis using two mobile phases (methanol: chloroform at 4:1 and 1:1 ratios). UV spectrophotometry was employed to determine the maximum absorbance wavelength and quantify sildenafil citrate. Results: TLC analysis revealed that two samples (K and L) contained sildenafil citrate, with Rf values consistent with the standard. UV spectrophotometry confirmed the presence of sildenafil citrate at a maximum wavelength of 292.5 nm. Sample K contained 0.96%, while sample L had 13.766% sildenafil citrate. Conclusion: The presence of sildenafil citrate in two samples violates Indonesian regulations prohibiting medicinal chemicals in herbal products, raising significant safety concerns.

Investigating the acceptor tuned effect on INPOD-based efficient D-π-A organic chromophores for optoelectronic utilization through quantum chemical analysis

In this study, the dye-sensitized solar cells and non-linear optical capabilities of newly designed ((E)-2-amino-5-((5-(4-p-tolyl-1,2,3,3a, 4,8 b-hexahydrocyclopenta [b]indol-7-yl)thiophen-2-yl)methylene)thiazol-4(5H)-one (INPOD)-based A1-A6 organic chromophores were examined. To create a D-π-A structure, the A1-A6 molecules were positioned on the electron donor, spacer, and acceptor, respectively. The use of hybrid functionals including PBEPBE, CAM-B3LYP, and MPW1PW91 was evaluated for the maximum absorption wavelength of INPOD. According to the calculated outcomes, MPW1PW91 exhibited λmax closest to INPOD. Consequently, the optical absorption spectra of A1-A6 were employed by this method to identify the key factors. The photovoltaic characteristics of these compounds in dye-sensitized solar cells were studied theoretically. The acceptor category affected the photovoltaic performance of A1-A6. Through the quantum chemical technique in time-dependent density functional theory methods, the electronic charge distribution and intramolecular charge transfer inside the A1-A6 were found. Time-dependent density functional theory calculations revealed that all A1-A6 had a λmax, that was greater than the INPOD (437 nm) in the range of 564–806 nm. A6 demonstrated an electron reorganization energy of 0.2340 eV, while a hole reorganization energy of 0.1006 eV. These values represent the maximum mobility of holes and electrons among all values. Additionally, the open circuit voltage was calculated after coupling each compound with a PTB7-Th. By the Voc of 2.10, 2.06, 2.22, and 2.08 eV, the A1, A3, A4, and A5 dyes produced the best results, respectively. The A1-A6 sensitizers were used to derive the non-linear optical properties of the dipole moment, polarizability, and first-order hyperpolarizability. It was noticed from the calculated results that the A2 and A6 molecules have the best options for non-linear optical activity. It tested how well the A1-A6 dyes performed in terms of charge transfer, dye regeneration, electron injection driving force, light harvesting efficiency, transition density matrix, molecular electro-potential, and density of states. The computed result showed that A2 and A6 chromophores are excellent candidates for dye-sensitized solar cells. Finally, those dye derivatives would certainly work effectively as tuning-A in optoelectronic applications.

Molecular design and characterization of the PANI/yttrium oxide multifunctional nanocomposite material

A detailed density functional theory study was conducted on the nanocomposites formed by polyaniline and yttrium oxide clusters, employing the mixed 6-311G(d,p)/LANL2DZ basis set. The investigation identified the formation of the nanocomposites through strong covalent bonding and moderate electrostatic interactions, resulting in significant binding energies. These interactions contributed to a reduction in the band gap, increased electron activity, and higher chemical reactivity compared to pure polyaniline. The formation of the nanocomposites induced a redshift in the UV–vis absorption spectra, moving the maximum absorption wavelength from the ultraviolet to the visible region, indicating n-type doping. Natural bond orbital analysis confirmed the role of yttrium oxide clusters as electron acceptors, with polyaniline serving as an electron donor.

Readily constructed squaraine J-aggregates with an 86.0 % photothermal conversion efficiency for photothermal therapy

The development of photothermal agents with high photothermal conversion efficiency (PCE) and long absorption wavelengths is crucial for safe and effective anti-cancer treatment. However, achieving these advantages often requires precise molecular design and complex synthetic procedures. In this study, we present a simple, precise, and effective method for fabricating photothermal agents with high PCE using long wavelength excitation. This approach involves linking two electron-donating components, diphenylamine (DPA), and an electron-withdrawing squaraine (SQ), via a π-bridge thiophene (T). The resulting D-π-A-π-D structure leads to a red-shifted absorption band. Within the DTS structure, DPA functions as a molecular rotor, T serves as a coplanar backbone, and SQ promotes J aggregation. When DTS nanoparticles (NPs) are fabricated using an amphiphilic nano-carrier, the maximum absorption wavelength shifts from 701 to 803 nm. This shift is accompanied by reduced fluorescence and an exceptionally high PCE of 86.0 %. Both in vitro and in vivo assessments confirm that DTS NPs exhibit strong potential for photothermal antitumor therapy. Overall, this strategy offers a valuable framework for designing photothermal agents with clinical applications in mind, offering a simpler and more efficient approach to achieving high PCE and long absorption wavelengths.

Near-infrared probes based on the phenanthridinium for dynamic monitoring of viscosity fluctuations during mitophagy

Abnormal changes in the mitochondrial microenvironment can cause a variety of diseases. Consequently, based on the twisted intramolecular charge transfer (TICT) theory, three hemicyanine fluorescent probes 1a-c were designed and developed by linking the phenanthridine group with different electron donor groups for the dynamic detection of mitochondrial viscosity in this paper. They have the advantages of near-infrared emission, excellent pH stability and viscosity sensitivity. Optical experiments showed that the maximum absorption and emission wavelengths of the probes in different solvents located at 411 − 529 nm and 623 − 684 nm with large Stokes shifts of 133 – 230 nm. In addition, when the viscosity increased from 0.89 cP to 856 cP, their fluorescence intensities in glycerol enhanced by 115-fold, 83-fold and 303-fold compared with water, respectively. The fluorescence intensities of probes showed excellent fit to the Forster Hoffmann equation, and exhibited nearly OFF-ON response to viscosity. Moreover, the probe 1a with good photostability and low cytotoxicity could target mitochondria. It was verified that 1a also could detect variation in mitochondrial viscosity during autophagy by modelling starvation and drug-induced (rapamycin and nystatin) in HeLa cells. Therefore, this study provides a useful probe for the analysis of mitophagy process in HeLa cells by the viscosity variation of mitochondria.

Photocatalytic removal of aldrin and dieldrin using graphene oxide and TiO2‐doped CuFe2O4

AbstractBACKGROUNDConventional treatment processes and existing photocatalysts have proven insufficient in efficiently removing aldrin and dieldrin. Consequently, this study aimed to investigate the removal of aldrin and dieldrin from surface water using a titanium dioxide/graphene oxide/copper ferrite (TiO₂/GO/CuFe₂O₄) nanocomposite.RESULTSThe highest photodegradation efficiencies for aldrin (100%) and dieldrin (99%) were achieved with a TiO₂/GO/CuFe₂O₄ nanocomposite dosage of 1.3 mg L−1, at a sunlight intensity of 9 W m−2 and an optimal photodegradation time of 25 min. The maximum UV absorption wavelength of the TiO₂/GO/CuFe₂O₄ nanocomposite was observed at 365 nm. The quantum yield of the nanocomposite was recorded as 2.69 × 102 mol einstein−1, and its bandgap energy was determined to be 3.31 eV. The first‐order kinetic rate constants for aldrin and dieldrin were calculated as 0.05 and 0.047 min−1, respectively. X‐ray diffraction analysis confirmed the crystal structure of CuFe₂O₄/TiO₂, while Fourier transform infrared spectroscopy detected carboxylic, epoxy, carbonyl and other oxygenated groups within the TiO₂/GO/CuFe₂O₄ nanocomposite. Scanning electron microscopy and transmission electron microscopy images revealed that CuFe₂O₄ was situated on the outer layer of GO. Energy‐dispersive X‐ray analysis identified the elemental composition of the TiO₂/GO/CuFe₂O₄ nanocomposite as comprising GO, C, Cu, Fe, Ti and O. A reusability study demonstrated that the nanocomposite maintained excellent performance, achieving 99% removal efficiency after 79 cycles and 97% after 100 cycles.CONCLUSIONSThe TiO₂/GO/CuFe₂O₄ nanocomposite effectively removed aldrin and dieldrin from surface water. This nanocomposite holds promise for the remediation of other aquatic ecosystems, such as bays, rivers and ocean waters. © 2024 The Author(s). Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Molecular engineering on tyrian puprle natural dye as TiO2 based fined tuned photovoltaic dye material: DFT molecular analysis

In this research, molecular modification is employed to see the enhancement in the efficiency of Tyrian Purple (TP), a natural dye, for organic photovoltaic materials. By using Density Functional Theory (DFT) based molecular modeling, seven new structures are designed with pi spacer to extend electron donor moieties. Teheir Frontier Molecular Orbital (FMO) analysis demonstartes their charges with a similar pattern of distributions over their Highest Occupied and Lowed Unocuupied Molecular Orbitals (HOMO/lUMO). This analysls also show their energy gaps (Egaps) to range around 2.97–3.02 eV. Their maximum absorption wavelength (λmax) demosntartes 486–490 nm range to indicate their tendency of absorbing light efficiently. Their Transition Density Matrix (TDM) analysis also reveals their facile electronic transitions without a significant charges over spacers. From calculating their photovoltaic paramters, their Light Harvesting Efficiency (LHE) reaches to 72.4–95.5 %. Also their Open Circuit Voltage (Voc) varies across 1.16–1.34 V. It is found that dyes actively adsorb onto TiO2 clusters to demonstrate their promise for tuning their Conduction Band (CB). This research is an effort for to evaluate the structural correlations to the develop photovoltaic materials through molecular-level design and optimization.

Novel Ketone Derivatives Involving Triphenylamine Electron‐Donating Group as Low Migration Photoinitiators for Visible Light Radical Polymerization and 3D Printing

AbstractGiven the ongoing advancements in photopolymerization technology, there is an imperative need to develop novel free radical photoinitiators (PIs) with long‐wavelength absorbance and low migration. To meet the demand for visible light photopolymerization, four novel ketone derivatives photoinitiators (PHMOs) were synthesized in this study via a one‐step reaction. By constructing the push‐pull structure, the maximum absorption wavelength of the new PIs was red‐shifted to the vicinity of 400 nm, satisfying the requirement of visible excitation. The one‐component photoinitiation effect of PHMOs under visible light was comparable to that of Irgacure 1173, among which the photopolymerisation performance of PHMO‐2 was significantly superior to that of 1173. The photopolymerization effect of the two‐component photoinitiaton system composed by the addition of hydrogen donor was significantly improved. PHMO‐1 was successfully used in 3D printing to produce well‐defined printed products. The photolysis mechanism of PHMOs was investigated by steady‐state photolysis and electron spin resonance test. In addition, PHMOs had good solubility, thermal stability and good biosafety. Attributed to the presence of double bonds, PHMOs had low migration. These excellent properties indicated that PHMOs had desirable potential applications in the field of visible light polymerization.

Magnetic solid-phase extraction of amoxicillin and doxycycline from water and urine samples based on cetylpyridinium chloride-modified Fe3O4 nanoparticles followed by spectrophotometric determination.

This research describes an easy, rapid, and inexpensive magnetic solid-phase extraction (MSPE) approach employing Fe3O4 magnetic nanoparticles modified with cetylpyridinium chloride (Fe3O4@CPC/MNPs) for extracting amoxicillin (AMX) and doxycycline (DOX) after derivatization with 4-chloroaniline as a color reagent. The azo-coupling of AMX and DOX with the color reagent in the alkaline medium caused yellow and yellow-orange azo dyes with maximum absorption wavelengths of 435 and 438 nm, respectively. The UV-Vis spectroscopy was utilized to determine the target analyte after the extraction procedure. Good linearities (R2 > 0.99) in the concentration ranges of 0.03-4.50 and 0.05-6.00µg/mL were obtained for AMX and DOX, respectively. The experimental detection limits of AMX and DOX were obtained as 0.01 and 0.02 µg/mL, respectively. The developed approach was effectively applied to pre-concentrate and quantify AMX and DOX in environmental water and urine samples.

Comprehensive Analysis of Phycoerythrin 545 Stability and the Apoptotic Impact of Its Degradation Products on HT29 Cells.

This study investigates the properties and potential applications of phycoerythrin 545, a naturally occurring light-harvesting pigment protein from Rhodomonas salina. Phycoerythrin 545, characterized by its bright red color and maximum absorption wavelength at 545 nm, was extracted using freeze-thawing methods, further purified, and analyzed using chromatographic, spectroscopic techniques, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Phycoerythrin 545 consists of two subunits, primarily α and β, but lacks the γ subunit, and is stable at 4 °C within a pH range of 3-10. To further characterize it, its susceptibility to degradation by trypsin was assessed. The biological activity of phycoerythrin 545 and its degradation products were investigated in HT29 human colon cancer cells. The results showed that the degradation products, particularly those within 3-10 kDa, significantly decreased the viability of HT29 cells by inducing apoptosis. Mechanistic studies indicated these effects were mediated through the activation of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinases and MAPK/c-Jun N-terminal Kinase signaling pathways and involved the regulation of key apoptotic proteins such as p53, Bim, Bad, Bak, and Bax, leading to the activation of the Caspase-3 apoptotic pathway. These findings contribute to understanding the structural and functional properties of phycoerythrin 545, laying a foundation for its exploration in food industry applications and cancer therapy supplementation.

A mitochondria-targeted near-infrared fluorescent probe for pH monitoring in living cells based on the rhodamine-hemicyanine hybrid structure

Mitochondrial pH plays a crucial role in cellular metabolism and pathological conditions. Thus, tracking changes in mitochondrial pH is essential for understanding its impact on cellular processes. In this work, we report a mitochondria-targetable near-infrared pH-sensitive fluorescent probe, Rh-NorCy, based on the rhodamine-hemicyanine hybrid structure. Rh-NorCy contains a non-alkylated indolenine moiety as recognition site of pH and a triphenylphosphonium moiety as the mitochondria-targeting group. As the solution pH decreases from 9.1 to 5.8, the indolium N atom in the Rh-NorCy structure undergoes protonation, leading to a red shift of its maximum absorption wavelength from 568 nm to 709 nm and a significant fluorescence enhancement at 748 nm simultaneously. Importantly, Rh-NorCy exhibits a suitable pKa (7.27) to map the pH variation in the mitochondria. Rh-NorCy demonstrates excellent photostability, minimal cytotoxicity, and strong mitochondria-targeting capability. It has been used to observe mitochondrial pH fluctuations during starvation and carbonylcyanide m-chlorophenylhydrazone (CCCP)-induced mitophagy.

DFT insights into the nonlinear optical properties of azulene-stilbene dyads for photonics and optoelectronics

The present study aims to investigate the nonlinear optical characteristics of a series of azulene-stilbene chromophores through the utilization of density functional theory (DFT). Various acceptor substitution techniques were used to enhance first, second, and third order static and dynamic polarizabilities of the parent azulene-stilbene dyad (AS). The natural transition orbitals and UV-Visible absorption spectra were analyzed using time dependent-density functional theory (TD-DFT). Theoretical computations were performed to analyze the structural, electronic, and charge transfer properties of all designed compounds. The energy gap separating the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the designed moieties was observed to decrease in the new compounds compared to the parent compound. Analysis of the nonlinear optical (NLO) data among the designed compounds (AS1-AS10) revealed that AS2, AS3, AS4, and AS10 exhibit promising second and third order NLO characteristics, with AS6 exhibits suitability as a second order NLO material and AS8 and AS9 display third order NLO responses. The computed static and dynamic NLO parameters and maximum absorption wavelength closely match the experimentally reported data in the literature, suggesting these derivatives are excellent candidates for photonic and optoelectronic applications in the future.

Highly Stable Binary Cross‐Linkable Organic Nonlinear Optical Materials Using Different Acceptors Based on Huisgen Cycloaddition Reaction

Comprehensive SummaryHow to obtain organic electro‐optic materials with large electro‐optic coefficients, high glass transition temperature, and good optical transparency remains a challenge in this field. To solve this problem, we introduce groups that can undergo Huisgen cycloaddition reactions into the donor and electron bridge of chromophores with large hyperpolarizability using tetrahydroquinoline as the donor. Binary cross‐linkable chromophores TLD1‐2 with CF3‐TCF as the acceptor and chromophores TLD3‐4 with 5Fph‐TCF as the acceptor were synthesized. After poling and crosslinking, the Tg of TLD1/TLD2 and TLD3/TLD4 were raised to 152 and 174 °C, respectively. The electro‐optical coefficients of chromophores TLD1/TLD2 and TLD3/TLD4 were as high as 312 pm/V and 287 pm/V, respectively. The long‐term alignment stability test showed that after being left at 85 °C for 500 h, the cross‐linked film TLD3/TLD4 can still maintain more than 98% of the original electro‐optical coefficient value, which is higher than that of TLD1/TLD2 (93%). The chromophore TLD3‐4 exhibited much blue‐shifted maximum absorption wavelengths (~40 nm) compared to TLD1‐2 which was beneficial for reducing optical loss in the device. The combination of high electro‐optic coefficient, strong stability, and excellent optical transparency makes the TLD series of binary cross‐linked materials very promising for practical high‐performance electro‐optic devices.

Gold nanoparticles for photothermal therapy – Influence of experimental conditions on the properties of resulting AuNPs

Gold nanoparticles (AuNPs)-mediated Photothermal Therapy (PTT) is a minimally-invasive therapeutic approach that uses AuNPs to convert light into heat, leading to the thermal ablation of tumors. Thus, the efficacy of this strategy strongly relies on the photothermal conversion potential of AuNPs. The ability to convert light into heat can be enhanced by tuning the physicochemical and optical properties of AuNPs. This can be achieved by changing the conditions of AuNP's synthesis, such as the order of addition of reagents. The present work entails to explore how varying the order of reagents addition modulates the properties of AuNPs, particularly enhancing the photothermal conversion potential of the resulting AuNPs and consequently, improving PTT efficacy. For this, eleven different AuNPs' nanoformulations were synthetized following different sequences of addition of reagents. These nanoformulations were characterized regarding their physicochemical properties namely size, surface charge, gold concentration, surface morphology and maximum absorbance wavelength. In addition, their thermal activation profiles were determined in vitro. Furthermore, the biocompatibility of different nanoformulations was also assessed. Three nanoformulations, with the most favorable photothermal activation profiles (AuNPs 2, 3 and 7), were then selected for preliminary in vitro safety and efficacy assays using a panel of cell lines. These three nanoformulations were deemed safe in vitro at the tested concentrations. At 250 μM of gold content, and after an incubation period of 4 h, followed by 5 min irradiation with a laser emitting at 808 nm (7.96 W/cm2), AuNPs 7 significantly reduced the cell viability of all cancer cell lines tested (MCF-7, HCT-116 and A375) by ≥ 45 %. However, such cytotoxic effect was not observed for the human keratinocyte cell line (HaCat), thus demonstrating its specificity towards cancer cells. Overall, the results herein presented reinforce that the order of reagents addition is highly important for achieving adequate AuNPs for PTT.

NIR‐induced upconversion‐assisted photopolymerization: Key factors, challenges, and future directions

AbstractNIR‐induced upconversion‐assisted photopolymerization has gained growing attention in the past two decades because of its numerous advantages over conventional UV/visible photopolymerization and two‐photon polymerization processes. However, research in this area is still in its early stages. To extend the practical application of NIR‐induced radiation curing, it is essential to optimize the factors affecting the photopolymerization reactions. Researchers have been constantly trying to improve these factors to tune the photo‐physical characteristics (luminescence intensity and color) of upconversion particles (UCPs), enhance curing depths and degree of double bond conversion (DC), and investigate the application of UCPs in emerging fields. In this review, first, a brief discussion of the upconversion mechanisms and upconversion efficiency is provided. Then, a detailed discussion of the factors influencing the upconversion‐assisted photopolymerization comprising UCP nature and characteristics, UCP content, presence of fillers/pigments/additives, laser intensity, photoinitiator content, and maximum absorption wavelength of photoinitiator is provided, and recent progress in improving these factors is presented. Finally, the advantages and drawbacks of the UC‐initiated polymerization are discussed, and perspectives for future directions are suggested.Highlights NIR‐induced upconversion‐assisted photopolymerization garners growing interest. Influential factors in upconversion‐assisted photopolymerization are thoroughly discussed. The recent progress on improving these factors and the future directions are provided.