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13 pages, 2230 KiB

Open AccessArticle

Sensing and Microbiological Activity of a New Blue Fluorescence Polyamidoamine Dendrimer Modified with 1,8-Naphthalimide Units

by Ivo Grabchev, Albena Jordanova, Evgenia Vasileva-Tonkova and Ivan L. Minkov

Molecules 2024, 29(9), 1960; https://doi.org/10.3390/molecules29091960 - 25 Apr 2024

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Abstract

A novel second-generation blue fluorescent polyamidoamine dendrimer peripherally modified with sixteen 4-N,N-dimethylaninoethyloxy-1,8-naphthalimide units was synthesized. Its basic photophysical characteristics were investigated in organic solvents of different polarity. It was found that in these solvents, the dendrimer is colorless and emitted blue [...] Read more.

A novel second-generation blue fluorescent polyamidoamine dendrimer peripherally modified with sixteen 4-N,N-dimethylaninoethyloxy-1,8-naphthalimide units was synthesized. Its basic photophysical characteristics were investigated in organic solvents of different polarity. It was found that in these solvents, the dendrimer is colorless and emitted blue fluorescence with different intensities depending on their polarity. The effect of the pH of the medium on the fluorescence intensity was investigated and it was found that in the acidic medium, the fluorescence is intense and is quenched in the alkaline medium. The ability of the dendrimer to detect metal ions (Pb²⁺, Zn²⁺, Mg²⁺, Sn²⁺, Ba²⁺, Ni²⁺, Sn²⁺, Mn²⁺, Co²⁺, Fe³⁺, and Al³⁺) was also investigated, and it was found that in the presence of Fe³⁺, the fluorescent intensity was amplified more than 66 times. The antimicrobial activity of the new compound has been tested in vitro against Gram-positive B. cereus and Gram-negative P. aeruginosa. The tests were performed in the dark and after irradiation with visible light. The antimicrobial activity of the compound enhanced after light irradiation and B. cereus was found slightly more sensitive than P. aeruginosa. The increase in antimicrobial activity after light irradiation is due to the generation of singlet oxygen particles, which attack bacterial cell membranes. Full article

(This article belongs to the Special Issue Advances in Fluorescent Probe Technology)

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14 pages, 3774 KiB

Open AccessArticle

Design and Synthesis of Novel Squaraine-Based Fluorescent Probe for Far-Red Detection of Chymotrypsin Enzyme

by Shekhar Gupta, Priyanka, Sai Kiran Mavileti, Shyam S. Pandey and Tamaki Kato

Molecules 2024, 29(6), 1282; https://doi.org/10.3390/molecules29061282 - 14 Mar 2024

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Abstract

Chymotrypsin, a crucial enzyme in human digestion, catalyzes the breakdown of milk proteins, underscoring its significance in both health diagnostics and dairy quality assurance. Addressing the critical need for rapid, cost-effective detection methods, we introduce a groundbreaking approach utilizing far-red technology and HOMO-Förster [...] Read more.

Chymotrypsin, a crucial enzyme in human digestion, catalyzes the breakdown of milk proteins, underscoring its significance in both health diagnostics and dairy quality assurance. Addressing the critical need for rapid, cost-effective detection methods, we introduce a groundbreaking approach utilizing far-red technology and HOMO-Förster resonance energy transfer (FRET). Our novel probe, SQ-122 PC, features a unique molecular design that includes a squaraine dye (SQ), a peptide linker, and SQ moieties synthesized through solid-phase peptide synthesis. Demonstrating a remarkable quenching efficiency of 93.75% in a tailored H₂O:DMSO (7:3) solvent system, our probe exhibits absorption and emission properties within the far-red spectrum, with an unprecedented detection limit of 0.130 nM. Importantly, our method offers unparalleled selectivity towards chymotrypsin, ensuring robust and accurate enzyme detection. This pioneering work underscores the immense potential of far-red-based homo-FRET systems in enabling the sensitive and specific detection of chymotrypsin enzyme activity. By bridging the gap between cutting-edge technology and biomedical diagnostics, our findings herald a new era of enzyme sensing, promising transformative advancements in disease diagnosis and dairy quality control. Full article

(This article belongs to the Special Issue Advances in Fluorescent Probe Technology)

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11 pages, 6932 KiB

Open AccessCommunication

A Novel Fluorescence Sensor for Iodide Detection Based on the 1,3-Diaryl Pyrazole Unit with AIE and Mechanochromic Fluorescence Behavior

by Lili Deng, Jian Xiong, Wenqin Liu, Lixue Wu, Huiyi Hu, Jiaqing Wu, Yue Liu, Lide Yu, Yuling Zhou, Wenjun Gao, Haifeng He and Weiyan Yin

Molecules 2023, 28(20), 7111; https://doi.org/10.3390/molecules28207111 - 16 Oct 2023

Cited by 2 | Viewed by 1083

Abstract

A D−A type of luminophore, TPA-CDP, was designed and synthesized by using triphenylamine (TPA) as D (electron donor), 1,3-diaryl pyrazole with cyano groups (CDP) as A (electron acceptor) and employing a cyanovinyl segment as a recognition group. Firstly, TPA-CDP demonstrates effective fluorescence quenching [...] Read more.

A D−A type of luminophore, TPA-CDP, was designed and synthesized by using triphenylamine (TPA) as D (electron donor), 1,3-diaryl pyrazole with cyano groups (CDP) as A (electron acceptor) and employing a cyanovinyl segment as a recognition group. Firstly, TPA-CDP demonstrates effective fluorescence quenching as a sensor for I⁻ by the nucleophilic addition reaction of the cyanovinyl segment with a high level of sensitivity, selectivity and a low determination limit of 4.43 μM. Interestingly, TPA-CDP exhibited an AIE phenomenon with the f_w value reaching 50%. In addition, TPA-CDP displayed distinct mechanochromic fluorescence behavior with 70 nm red shift, which was observed over four repeated cycles. Furthermore, the mechanochromic fluorescence behavior of TPA-CDP, as observed in powder XRD experiments, was found to be associated with the morphological transition from a crystalline state to an amorphous state. These results confirm the significant potential of CDP as a powerful electron-deficient component in the creation of D−A-type mechanochromic fluorescence materials and biosensors for detecting I⁻. Full article

(This article belongs to the Special Issue Advances in Fluorescent Probe Technology)

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11 pages, 2240 KiB

Open AccessArticle

Enantioselective Labeling of Zebrafish for D-Phenylalanine Based on Graphene-Based Nanoplatform

by Yuqing He, Ziqi Ye, Fei Zhu, Tianxiang Qiu, Xiyan Dai, Yue Xie, Shibiao Zou, Qingjian Dong, Weiying Zhang, Junkai Ma and Xiaowei Mao

Molecules 2023, 28(9), 3700; https://doi.org/10.3390/molecules28093700 - 25 Apr 2023

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Abstract

Enantioselective labeling of important bioactive molecules in complex biological environments by artificial receptors has drawn great interest. From both the slight difference of enantiomers’ physicochemical properties and inherently complexity in living organism point of view, it is still a contemporary challenge for preparing [...] Read more.

Enantioselective labeling of important bioactive molecules in complex biological environments by artificial receptors has drawn great interest. From both the slight difference of enantiomers’ physicochemical properties and inherently complexity in living organism point of view, it is still a contemporary challenge for preparing practical chiral device that could be employed in the model animal due to diverse biological interference. Herein, we introduce γ-cyclodextrin onto graphene oxide for fabricating γ-cyclodextrin and graphene oxide assemblies, which provided an efficient nanoplatform for chiral labelling of D-phenylalanine with higher chiral discrimination ratio of K_D/K_L = 8.21. Significantly, the chiral fluorescence quenching effect of this γ-CD-GO nanoplatform for D-phenylalanine enantiomer in zebrafish was 7.0-fold higher than L-isomer, which exhibiting real promise for producing practical enantio-differentiating graphene-based systems in a complex biological sample. Full article

(This article belongs to the Special Issue Advances in Fluorescent Probe Technology)

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15 pages, 3198 KiB

Open AccessArticle

Development of Highly Efficient Estrogen Receptor β-Targeted Near-Infrared Fluorescence Probes Triggered by Endogenous Hydrogen Peroxide for Diagnostic Imaging of Prostate Cancer

by Pei He, Xiaofei Deng, Bin Xu, Baohua Xie, Wenting Zou, Haibing Zhou and Chune Dong

Molecules 2023, 28(5), 2309; https://doi.org/10.3390/molecules28052309 - 02 Mar 2023

Cited by 2 | Viewed by 1532

Abstract

Hydrogen peroxide is one of the most important reactive oxygen species, which plays a vital role in many physiological and pathological processes. A dramatic increase in H₂O₂ levels is a prominent feature of cancer. Therefore, rapid and sensitive detection of [...] Read more.

Hydrogen peroxide is one of the most important reactive oxygen species, which plays a vital role in many physiological and pathological processes. A dramatic increase in H₂O₂ levels is a prominent feature of cancer. Therefore, rapid and sensitive detection of H₂O₂ in vivo is quite conducive to an early cancer diagnosis. On the other hand, the therapeutic potential of estrogen receptor beta (ERβ) has been implicated in many diseases including prostate cancer, and this target has attracted intensive attention recently. In this work, we report the development of the first H₂O₂-triggered ERβ-targeted near-infrared fluorescence (NIR) probe and its application in imaging of prostate cancer both in vitro and in vivo. The probe showed good ERβ selective binding affinity, excellent H₂O₂ responsiveness and near infrared imaging potential. Moreover, in vivo and ex vivo imaging studies indicated that the probe could selectively bind to DU-145 prostate cancer cells and rapidly visualizes H₂O₂ in DU-145 xenograft tumors. Mechanistic studies such as high-resolution mass spectrometry (HRMS) and density functional theory (DFT) calculations indicated that the borate ester group is vital for the H₂O₂ response turn-on fluorescence of the probe. Therefore, this probe might be a promising imaging tool for monitoring the H₂O₂ levels and early diagnosis studies in prostate cancer research. Full article

(This article belongs to the Special Issue Advances in Fluorescent Probe Technology)

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10 pages, 3532 KiB

Open AccessArticle

Ratiometric Singlet Oxygen Sensor Based on BODIPY-DPA Dyad

by Alexey A. Pakhomov, Anastasia S. Belova, Arevik G. Khchoyan, Yuriy N. Kononevich, Dmitriy S. Ionov, Margarita A. Maksimova, Anastasiya Yu. Frolova, Mikhail V. Alfimov, Vladimir I. Martynov and Aziz M. Muzafarov

Molecules 2022, 27(24), 9060; https://doi.org/10.3390/molecules27249060 - 19 Dec 2022

Cited by 1 | Viewed by 2010

Abstract

Compounds sensitive to reactive oxygen species are widely used in the study of processes in living cells and in the development of therapeutic agents for photodynamic therapy. In the present work, we have synthesized a dyad in which the BODIPY dye is chemically [...] Read more.

Compounds sensitive to reactive oxygen species are widely used in the study of processes in living cells and in the development of therapeutic agents for photodynamic therapy. In the present work, we have synthesized a dyad in which the BODIPY dye is chemically bound to 9,10-diphenylanthracene (DPA). Here, DPA acts as a specific sensor of singlet oxygen and BODIPY as a reference dye. We studied the photophysical properties of the BODIPY-DPA dyad and showed that energy transfer occurs between the chromophores. As a result, the compound has excitation maxima in the absorption region of both DPA and BODIPY, but the fluorescence emission occurs mainly from BODIPY. In the presence of singlet oxygen, the excitation maximum of DPA decreases, while the intensity of the excitation maximum of BODIPY remains almost unchanged. This allows the BODIPY-DPA dyad to be used as a ratiometric sensor of singlet oxygen. Full article

(This article belongs to the Special Issue Advances in Fluorescent Probe Technology)

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Review

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27 pages, 3651 KiB

Open AccessReview

Recent Advances in Biological Applications of Aptamer-Based Fluorescent Biosensors

by Minhyuk Lee, Seonhye Shin, Sungjee Kim and Nokyoung Park

Molecules 2023, 28(21), 7327; https://doi.org/10.3390/molecules28217327 - 29 Oct 2023

Cited by 4 | Viewed by 1689

Abstract

Aptamers have been spotlighted as promising bio-recognition elements because they can be tailored to specific target molecules, bind to targets with a high affinity and specificity, and are easy to chemically synthesize and introduce functional groups to. In particular, fluorescent aptasensors are widely [...] Read more.

Aptamers have been spotlighted as promising bio-recognition elements because they can be tailored to specific target molecules, bind to targets with a high affinity and specificity, and are easy to chemically synthesize and introduce functional groups to. In particular, fluorescent aptasensors are widely used in biological applications to diagnose diseases as well as prevent diseases by detecting cancer cells, viruses, and various biomarkers including nucleic acids and proteins as well as biotoxins and bacteria from food because they have the advantages of a high sensitivity, selectivity, rapidity, a simple detection process, and a low price. We introduce screening methods for isolating aptamers with q high specificity and summarize the sequences and affinities of the aptamers in a table. This review focuses on aptamer-based fluorescence detection sensors for biological applications, from fluorescent probes to mechanisms of action and signal amplification strategies. Full article

(This article belongs to the Special Issue Advances in Fluorescent Probe Technology)

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16 pages, 9518 KiB

Open AccessReview

Two-Photon Fluorescent Probes for Amyloid-β Plaques Imaging In Vivo

by Yi Chen

Molecules 2023, 28(17), 6184; https://doi.org/10.3390/molecules28176184 - 22 Aug 2023

Viewed by 1027

Abstract

Amyloid-β (Aβ) peptide deposition, hyperphosphorylated tau proteins, reactive astrocytes, high levels of metal ions, and upregulated monoamine oxidases are considered to be the primary pathological markers of Alzheimer’s disease (AD). Among them, Aβ peptide deposition or Aβ plaques, is regarded as the initial [...] Read more.

Amyloid-β (Aβ) peptide deposition, hyperphosphorylated tau proteins, reactive astrocytes, high levels of metal ions, and upregulated monoamine oxidases are considered to be the primary pathological markers of Alzheimer’s disease (AD). Among them, Aβ peptide deposition or Aβ plaques, is regarded as the initial factor in the pathogenesis of AD and a critical pathological hallmark in AD. This review highlights recently Aβ-specific fluorescent probes for two-photon imaging of Aβ plaques in vivo. It includes the synthesis and detection mechanism of probes, as well as their application to two-photon imaging of Aβ plaques in vivo. Full article

(This article belongs to the Special Issue Advances in Fluorescent Probe Technology)

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