Carbon-Iodine Polydiacetylene Nanofibers for Image-Guided Radiotherapy and Tumor-Microenvironment-Enhanced Radiosensitization

Radiotherapy is a mainstay treatment used in clinics for locoregional therapy, although it still represents a great challenge to improve the sensitivity and accuracy of radiotherapy for tumors. Here, we report the conjugated polymer, polydiiododiacetylene (PIDA), with an iodine content of 84 wt %, as a highly effective computed tomography (CT) contrast agent and tumor microenvironment-responsive radiosensitizer. PIDA exhibited several key properties that contribute to the improvement of precision radiotherapy. The integrated PIDA nanofibers confined within the tumor envelope demonstrated amplified CT intensity and prolonged retention, providing an accurate calculation of dose distribution and precise radiation delivery for CT image-guided radiotherapy. Therefore, our strategy pioneers PIDA nanofibers as a bridge to cleverly connect a fiducial marker to guide accurate radiotherapy and a radiosensitizer to improve tumor sensitivity, thereby minimizing potential damage to surrounding tissues and facilitating on-demand therapeutic intervention in tumors.

Polyacetylene-Based Asymmetric Bicyclic Polymer by Blocking-Cyclization Technique

A rare asymmetric bicyclic polymer containing different length of conjugated polyacetylene segments is synthesized by metathesis cyclopolymerization-mediated blocking-cyclization technique. The size of each single ring differs from each other, and the unique cyclic polymer topology is controlled by adjusting the feed ratio of monofunctional monomer to catalyst. The topological difference between linear and bicyclic polymers is confirmed by several techniques, and the visualized morphology of asymmetric bicyclic polymer is directly observed without tedious post-modification process. The photoelectric and thermal properties of polymers are investigated. This work expands the pathway for the derivation of cyclic polymers, and such unique topological structure enriches the diversity of cyclic polymer classes.

Polydiacetylene rhodaminebased colorimetric chemosensor for Au3+ detection

A novel platform of a polydiacetylene combined with rhodamine B (PDA-Rho) colorimetric chemosensor array was prepared from a diacetylene monomer and rhodamine B derivative. Rhodamine B derivative as the ion-recognition element was embedded in the polydiacetylene matrix. To fabricate chemosensor, diacetylene monomer connected rhodamine B derivatives (DA-Rho) was coated onto a filter paper surface via drop-casting technique and transformed to polydiacetylene by polymerisation through ultraviolet (UV) irradiation. From the result, PDA-Rhoen exhibited high sensitivity and selectivity for Au3+ and could be monitored directly by naked eyes providing a fast, portable and easy-to-use as a molecular device in the real system. The DFT calculation results showed a stable complex between PDA-Rho and Au3+. We believe that, this method offers a sensitive and accurate process for Au3+ ion detection in real environmental and biological applications.

Detection of dopamine levels using a polydiacetylene liposomal aequorin bioluminescent device with octadecylboronic acid

The development of an easy-to-use and rapid method for the determination of dopamine levels is desirable for the diagnosis of neurological conditions, such as Parkinson's disease, which are characterized by low levels of dopamine. Herein, a polydiacetylene liposomal aequorin bioluminescent device (PLABD) containing octadecylboronic acid (OBA) as a recognition material (PLABD-OBA) was prepared for the determination of dopamine concentrations in aqueous solution. The bioluminescent signals of the photoprotein aequorin in PLABD-OBA increased according to increasing dopamine concentrations. The calibration curve showed good linearity over a dopamine concentration range of 70-700 µM (r = 0.918), with a detection limit of 7.5 µM. The addition of other catecholamines to the PLABD-OBA resulted in low bioluminescent signals of aequorin. Because the physiological levels of dopamine are generally 0.001-1.0 µM, this system had insufficient sensitivity for the clinical monitoring of dopamine levels. However, the PLABD-OBA developed herein is an easy-to-use and rapid analytical method that is specific for dopamine.

Polydiacetylene/lipid-coated red-emissive silica nanorods for the sustained release and ameliorated anticancer efficacy of a Ru(arene) complex bearing piperlongumine natural product

A suitable drug delivery strategy for metallodrugs is as significant as the strategies adopted for an efficient metallodrug design. In this study, piperlongumine, which is isolated from long pepper, is coordinated with a Ru(II)-p-cymene moiety to obtain an organoruthenated complex containing the natural product (Ru(pip)). The isolated complex shows higher cytotoxicity in MCF-7 breast cancer cells than in THP-1 leukemia and HepG2 liver cancer cells. The IC50 value of the complex in non-cancerous HEK-239 cells is also almost equal to that in MCF-7 cells. Next, with an aim to modulate the antiproliferative activity of Ru(pip) using a drug delivery strategy, the complex is loaded into mesoporous silica nanorods (MSNRs), which have a higher surface area than spherical silica nanoparticles. Furthermore, the outer surface of the loaded nanorods is covered with a polydiacetylene-lipid (PL) hybrid bilayer. Given the unique optical properties of polydiacetylene, the PL coating modifies non-fluorescent MSNRs into red-emissive particles (PL-Ru(pip)@MSNRs), which can be useful for diagnostic applications. The release profile studies reveal that the ene-yne conjugation in the PL coating ensures the sustained release of the complex from nanoparticles in both physiological and simulated cancer cell media. While Ru(pip) exhibits both necrotic and apoptotic modes of cell death, PL-Ru(pip)@MSNRs preferably induce the apoptotic mode of cell death in MCF-7 and THP-1 cells. Also, the nanoformulation exhibits a higher percentage of cell cycle arrest in the G0/G1 phase than Ru(pip), as measured by flow cytometry analysis. In contrast, the in vitro antioxidant potency of the complex is decreased after being loaded into PL-coated silica nanoparticles.

Design of an anticancer organoruthenium complex as the guest and polydiacetylene-coated fluorogenic nanocarrier as the host: engineering nanocarrier using ene-yne conjugation for sustained guest release, enhanced anticancer activity and reduced in vivo toxicity

Despite the enormous efforts made over the past two decades to develop metallodrugs and nanocarriers for metallodrug delivery, there are still few precise strategies that aim to optimize the design of both metallodrugs and metallodrug carriers jointly in a concerted effort. In this work, three half-sandwich ruthenium(II) complexes with pyridylimidazo[1,5-a]pyridine ligand functionalized with polycyclic aromatic moiety (Ru(nap), Ru(ant), Ru(pyr)) are evaluated as possible anticancer candidates and polydiacetylene (PDA)-coated amino-functionalized mesoporous silica nanoparticles (AMSNs) are designed as a functional nanocarrier for drug delivery. Ru(pyr) exhibits higher cytotoxicity in HT-29 colorectal cancer cells compared to other complexes and cis-platin, but it does not exhibit better cellular uptake. Ru(pyr) is found to be preferentially accumulated in plasma, mitochondria, and ER-Golgi membrane. The complex induces cell cycle arrest in the G0/G1 phase, while higher concentrations cause programmed cell death via apoptosis. Ru(pyr) influences cancer cell adhesion property and acts as an antioxidant in HT-29 cells. In order to modulate the anticancer potency of Ru(pyr), AMSNs are used to encapsulate the complex, and then diacetylene self-assembly is allowed to deposit on the surface of the nanoparticles. Subsequently, the nanoparticles undergo topopolymerization, which results in π-conjugated PDA-Ru(pyr)@AMSNs. Owing to the ene-yne polymeric skeleton in the backbone, the non-fluorescent AMSNs turn into red-emissive particles, which are exploited for cell imaging applications. The release profile analysis reveals that such a π-conjugated polymer prevents the premature release of the complex from porous silica nanoparticles with the accelerated release of the complex in an acidic medium compared to physiological conditions. The PDA gatekeepers have also been proven to enhance the cellular internalization of Ru(pyr) with slow continuous release from the nanoformulation. Zebrafish embryo toxicity analysis suggests that the PDA-coated nanocarriers could be suitable candidates for in vivo investigations.

Aptamer-functionalized polydiacetylene biosensor for the detection of three foodborne pathogens

Rapid, simple and sensitive screening of foodborne pathogens is of great significance to ensure food safety. In this study, an aptamer-functionalized polydiacetylene (Apta-PDA) biosensor was developed for the detection of E. coli O157:H7, S. typhimurium or V. parahaemolyticus. First, aptamers responding to the target bacteria were modified on the surface of magnetic beads by covalent binding to form MBs-oligonucleotide conjugates for bacterial enrichment. Then, an Apta-PDA biosensor was obtained by connecting the aptamers to the PDA nanovesicles using the carbodiimide method. Molecular recognition occurred in the presence of the target bacteria, whereby the aptamer folded into a sequence-defined unique structure, resulting in an MBs-Apta/bacteria/Apta-PDA sandwich structure. Due to the optical properties of PDA, the blue-red transition of the detection system could be observed by the naked eye and quantified by the colorimetric response percentage (CR%). Under optimized conditions, the detection limits of E. coli O157:H7, S. typhimurium and V. parahaemolyticus were 39, 60 and 60 CFU/ml, respectively, with a selectivity of 100% and a reaction time of 30 min. Compared with the gold standard method, the accuracy of the three target bacteria detection reached 98%, 97.5% and 97%, respectively, and the sensitivity and specificity were both greater than 90%. The entire detection process was rapid and easy to execute without any special equipment, making this technology particularly suitable for resource-poor laboratories or regions.

Polyacetylenes with xanthine oxidase inhibitory activity from the medicinal and edible fruits of Cyclocodon lancifolius (Roxburgh) Kurz

Five new polyacetylene derivatives (1-5), cyclocodonlandiynosides A-E, and eight known analogues (6-13) were isolated and identified from the fruits of Cyclocodon lancifolius. Their structures were established via spectroscopic and chemical methods, including NMR, HRESIMS, enzymatic hydrolysis, Mo2(OAc)4-induced circular dichroism and sugar derivatization. Compound 1 contains a nitrogenous fragment, which was rarely found in C14 polyacetylenes. Compounds 3 and 4 are polyacetylene glucosides possessing novel aglycones. All the isolated polyacetylenes (except 12) were screened for their xanthine oxidase (XO) inhibitory activity. All the tested compounds, at the concentration of 62.5 μg/mL, showed XO inhibiting effects. Among them, 13 and 3 showed the most potent XO inhibitory activity with IC50 values of 87.65 and 96.32 μM, compared to the positive control allopurinol with an IC50 value of 19.25 μM.

Thermochromic Behavior of Polydiacetylene Nanomaterials Driven by Charged Peptide Amphiphiles

The tunability of chromatic phases adapted by chromogenic polymers such as polydiacetylene (PDA) is key to their utility for robust sensing applications. Here, we investigated the influence of charged peptide interactions on the structure-dependent thermochromicity of amphiphilic PDAs. Solid-state NMR and circular dichroism analyses show that our oppositely charged peptide-PDA samples have distinct degrees of structural order, with the coassembled sample being in between the β-sheet-like positive peptide-PDA and the relatively disordered negative peptide-PDA. All solutions exhibit thermochromicity between 20 and 80 °C, whereby the hysteresis of the blue, planar phase is much larger than that of the red, twisted phase. Resonance Raman spectroscopy of films demonstrates that only coassemblies with electrostatic complementarity stabilize coexisting blue and red PDA phases. This work reveals the nature of the structural changes responsible for the thermally responsive chromatic transitions of biomolecule-functionalized polymeric materials and how this process can be directed by sequence-dictated electrostatic interactions.

Alkaloids and Polyacetylenes from Hippobroma longiflora with Antiangiogenesis Properties

Four new alkaloids, hippobrines A-D (1-4), along with three new polyacetylenes, hippobrenes A-C (5-7), were isolated from Hippobroma longiflora. Compounds 1-3 possess an unprecedented carbon skeleton. All of the new structures were determined by analyzing their mass and NMR spectroscopic data. The absolute configurations of 1 and 2 were confirmed by single-crystal X-ray analyses, and the absolute configurations of 3 and 7 were deduced using their ECD spectra. Plausible biogenetic pathways of 1 and 4 were proposed. In regard to bioactivities, all compounds (1-7) exhibited weak antiangiogenic activity against human endothelial progenitor cells, with IC₅₀ values ranging from 21.1 ± 1.1 to 44.0 ± 2.3 μg/mL.

Polyacetylenic caffeoyl amides from Ammodaucus leucotrichus

Six undescribed polyacetylenic caffeoyl amides, five known flavones and three known lignans were obtained from the fruits of the North African traditional medicinal plant Ammodaucus leucotrichus Coss. & Durieu (Apiaceae). Isolation was achieved by a combination of chromatographic methods, and structures were established by extensive 1D and 2D NMR spectroscopy, mass spectrometry, electronic circular dichroism, and by GC-MS analysis of sugar derivatives. Polyacetylenic caffeoyl amides are reported for the first time as specialized metabolites.

Stimuli-Responsive Sponge for Imaging and Measuring Weak Compression Stresses

Imaging and measuring compression stresses secure a safe and healthy life. Compression stresses in kPa range are not easily detected by conventional mechanoresponsive materials because microscopic molecular motion of the chromophores is not induced by such weak stresses. Moreover, imaging of the stress distribution is not achieved so far. The present study shows a sponge device combining two stimuli-responsive materials, a capsule releasing interior liquid and color-changing polymer in responses to compression stress and chemical stimulus, respectively. The stimuli-responsive capsule is dispersed on a melamine sponge comprised of the fibers with coating the layered polydiacetylene (PDA). The application of weak compression stresses induces collapse of the capsules, outflow of the interior liquid, and subsequent irreversible color change of PDA. The cascading response in the sponge device colorimetrically enables imaging of the distribution and measuring the strength of the compression stresses in kPa range. Furthermore, the device demonstrates imaging and measuring unknown weak compression stresses applied by the irregular-shaped objects. A couple of clinical issues in surgical operation of intestine are studied using the stress-imaging sponge device. The device and its design strategy can be applied to stress imaging in a variety of fields.

Platycodon grandiflorum (Jacq.) A. DC.: A review of phytochemistry, pharmacology, toxicology and traditional use

BACKGROUND

The traditional Chinese medicine Platycodon grandiflorum (Jacq.) A. DC. (PG, balloon flower) has medicinal and culinary value. It consists of a variety of chemical components including triterpenoid saponins, polysaccharides, flavonoids, polyphenols, polyethylene glycols, volatile oils and mineral components, which have medicinal and edible value.

PURPOSE

The ultimate goal of this review is to summarize the phytochemistry, pharmacological activities, safety and uses of PG in local and traditional medicine.

METHODS

A comprehensive search of published literature up to March 2022 was conducted using the PubMed, China Knowledge Network and Web of Science databases to identify original research related to PG, its active ingredients and pharmacological activities.

RESULTS

Triterpene saponins are the primary bioactive compounds of PG. To date, 76 triterpene saponin compounds have been isolated and identified from PG. In addition, there are other biological components, such as flavonoids, polyacetylene and phenolic acids. These extracts possess antitussive, immunostimulatory, anti-inflammatory, antioxidant, antitumor, antiobesity, antidepressant, and cardiovascular system activities. The mechanisms of expression of these pharmacological effects include inhibition of the expression of proteins such as MDM and p53, inhibition of the activation of enzymes, such as AKT, the secretion of inflammatory factors, such as IFN-γ, TNF-α, IL-2 and IL-1β, and activation of the AMPK pathway.

CONCLUSION

This review summarizes the chemical composition, pharmacological activities, molecular mechanism, toxicity and uses of PG in local and traditional medicine over the last 12 years. PG contains a wide range of chemical components, among which triterpene saponins, especially platycoside D (PD), play a strong role in pharmacological activity, representing a natural phytomedicine with low toxicity that has applications in food, animal feed and cosmetics. Therefore, PG has value for exploitation and is an excellent choice for treating various diseases.

A new dihydroflavone and a new polyacetylene glucoside from Bidens parviflora

A new dihydroflavone, 2(S)-isookanin-4'-methoxy-8-O-β-D-glucopyranoside (1), and a new polyacetylene glucoside, (10S)-tridecane-2E-ene-4,6,8-triyne-1-ol-10-O-β-D-glucopyranoside (2), along with seven known compounds (3-9), were isolated from the herb of Bidens parviflora Willd. The structures of all the extracted compounds were elucidated by HR-ESI-MS, 1 D and 2 D NMR spectra, as well as circular dichroism (CD).

Polyacetylenes in herbal medicine: A comprehensive review of its occurrence, pharmacology, toxicology, and pharmacokinetics (2014-2021)

Polyacetylenes are a kind of small active compounds with carbon-carbon triple bond with vast occurrence in plants. Polyacetylenes have attracted considerable attention owing to their diverse biofunctions like tumor suppression, immunity regulation, depression resistance and neural protection. The present review intends to reconstruct data concerning the occurrence, pharmacology, toxicology and pharmacokinetics of polyacetylenes from herbal medicine in a systematic and integrated way, with a view to backing up their curative potential and healthcare properties (2014-2021). The natural polyacetylene-related data were all acquired from the scientific search engines and databases that are globally recognized, such as PubMed, Web of Science, Elsevier, Google Scholar, ResearchGate, SciFinderⁿ and CNKI. A total of 183 polyacetylenes were summarized in this paper. Modern pharmacological studies indicated that polyacetylenes possess multiple biological activities including antitumor, immunomodulatory, neuroprotective, anti-depression, anti-obesity, hypoglycemic, antiviral, antibacterial, antifungal, hepatoprotective and renoprotective activities. As important bioactive components of herbal medicine, the pharmacological curative potential of polyacetylenes has been described against carcinomas, inflammatory responses, central nervous system, endocrine disorders and microbial infection in this review. While, further in-depth studies on the aspects of polyacetylenes for toxicity, pharmacokinetics, and molecular mechanisms are still limited, thereby intensive research and assessments should be performed.

Bifunctional ligand-mediated amplification of polydiacetylene response to biorecognition of diethylstilbestrol for on-site smartphone detection

Polydiacetylene (PDA) is very suited for sensitively detecting large biomolecules, and its unique chromatic properties enable visual read-out. However, application to the selective detection of small molecules remains challenging. Here, bifunctional ligands are studied to amplify the color change of PDA for biorecognition of small molecules for the smartphone-based detection of diethylstilbestrol (DES). PDA is decorated with streptavidin (PDA-SA, blue), and biotin-modified DES (bio-DES) is prepared as a bifunctional ligand to couple with PDA-SA and DES antibody. Since multiple bio-DES can bind to a single SA, then multiple SAs on PDA lead to an increased surface coverage of the vesicle. In samples without DES, PDA-SA-bio-DES-DES antibody complexes will form, leading to a color transition (blue to red); this color transition is greatly amplified by antibody-induced aggregation of the complexes. When DES is present, aggregation is inhibited due to competition for the antibody and PDA-SA-bio-DES retains its blue color. A linear relationship (0.4-1250 ng mL^-1) is found between the colorimetric response and the logarithmic DES concentration, with adequate selectivity, accuracy (82.24-118.64%), and precision (below 8.24%). Finally, a paper-based DES PDA biosensor is developed with visual and smartphone-based detection limits of 10 ng mL^-1 and 0.85 ng mL^-1 in water, respectively.

Structural diversity, biosynthesis, and function of plant falcarin-type polyacetylenic lipids

The polyacetylenic lipids falcarinol, falcarindiol, and associated derivatives, termed falcarins, have a widespread taxonomical distribution in the plant kingdom and have received increasing interest for their demonstrated health-promoting properties as anti-cancer and anti-inflammatory agents. These fatty acid-derived compounds are also linked to plant pathogen resistance through their potent antimicrobial properties. Falcarin-type polyacetylenes, which contain two conjugated triple bonds, are derived from structural modifications of the common fatty acid oleic acid. In the past half century, much progress has been made in understanding the structural diversity of falcarins in the plant kingdom, whereas limited progress has been made on elucidating falcarin function in plant-pathogen interactions. More recently, an understanding of the biosynthetic machinery underlying falcarin biosynthesis has emerged. This review provides a concise summary of the current state of knowledge on falcarin structural diversity, biosynthesis, and plant defense properties. We also present major unanswered questions about falcarin biosynthesis and function.

Label-free visible colorimetric biosensor for detection of multiple pathogenic bacteria based on engineered polydiacetylene liposomes

Bacterial infections are considered as a critical healthcare concern worldwide. Timely infection detection is crucial to effective antibiotic administration which can reduce the severity of infection and the occurrence of antibiotic resistance. We have developed label-free polydiacetylene (PDA) liposome-based colorimetric biosensor to detect and identify bacterial cultures at the genus and species level with naked eyes by simple color change. We found that among the various liposomal systems, moderate concentration of PDA, phospholipids and cholesterol in liposome assemblies can greatly influence the sensitivity to different bacteria, exhibiting unique chromatic properties of each bacterial strain. The strikingly different chromatic color change was due to the various mechanisms of interactions between bacterial toxins and biomimetic lipid bilayers. Furthermore, increase of cholesterol in liposome assemblies greatly enhanced the sensitivity of bacterial strains related to membrane destruction mediated by pore-formation mechanism such as S. aureus and E.coli, whereas the detection of the two bacterial strains was believed to rely on the specific recognition elements coupled with PDA moiety. As a proof of concept, a colorimetric finger-print array for distinguishing 6 bacterial species was studied. Particularly, the proposed bacterial detection platform is achieved through the interaction between bacterially secreted toxins and liposome bilayers instead of specific recognition of receptors-ligands. The results of both response time and sensitivity of label-free-liposome-based system show superior to previous reports on chromatic bacterial detection assays. By combing these results, the label-free-liposome-based colorimetric sensing platform shows great importance as a bacterial-sensing and discrimination platform.

Comprehensive characterization of polyacetylenes and diterpenes from the underground parts of Solidago altissima L. and their contribution to the overall allelopathic activity

Solidago altissima L. (Asteraceae), a perennial plant native to North America, is considered one of the most invasive weeds in Asia and Europe. The successful invasion of S. altissima is possibly due to its allelopathic effect along with high seed productivity and strong vegetative propagation through rhizomes. Herein, to understand the invasion of S. altissima via the allelopathic effect, we isolated and characterized known and undescribed compounds from the underground parts of S. altissima and evaluated their contribution to the overall allelopathic activity of the plant. NMR spectroscopy and LC-MS analyses clarified the chemical structure of ten specialized metabolites including three undescribed compounds, i.e., (4Z, 8Z)-10-tigloyloxy matricaria lactone, (4Z, 8Z)-10-angeloyloxy matricaria lactone, and (2Z, 8Z)-10-methacryloyloxy matricaria ester. The evaluation of the content and allelopathic ability of each compound showed that cis-dehydromatricaria ester contributes to the allelopathic activities of the S. altissima extract.

Plasmon-Enhanced Fluorescence in Electrospun Nanofibers of Polydiacetylenes Infused with Silver Nanoparticles

A hybrid computational and experimental approach was employed toward the rational design of a silver nanoparticle (AgNP)/polydiacetylene (PDA) metal-enhanced fluorophore (MEF) ensemble system contained within a poly(ethylene oxide) (PEO) electrospun nanofiber matrix for creation of high-performance sensors. Simulations based on Mie theory and finite-difference time domain (FDTD) algorithms were performed to understand and optimize spectral overlap between the AgNP localized surface plasmon resonance and the absorbance and emission spectra of PDA, a supramolecular polymer fluorophore. A series of AgNPs of varied sizes were investigated for fluorescence enhancement capability, and an optimal size of 134 nm in diameter was chosen for synthesis and incorporation into the electrospun nanofibers of a PDA/PEO composite for experimental characterization and confirmation. Results on individual nanofibers indicated a clear metal-enhanced fluorescence effect, and a 4.6-fold enhancement over neat PDA/PEO fluorescent nanofibers was observed. The nanofiber/nanoparticle/MEF ensemble system offers new avenues for generating effective sensing devices with polymeric fluorophores using a straightforward incorporation approach.

Characterizing and Tuning the Properties of Polydiacetylene Films for Sensing Applications

Self-assembled, polymerized diacetylene (DA) nanostructures and two-dimensional films have been studied over the past two decades for sensor applications because of their straightforward visual readout. DA monomers, when exposed to UV light, polymerize to produce a visibly blue polymer. Blue phase polydiacetylenes (PDAs) when exposed to an external stimuli, such as temperature or UV light, undergo a chromatic phase transition to a fluorescent, visibly red phase. The tunability of the monomer to blue to red chromatic phase transitions by choice of diacetylene monomer in the presence of metal cations is systematically and comprehensively investigated to determine their effects on the properties of PDA Langmuir films. The polymerization kinetics and domain morphology of the PDA films were characterized using polarized fluorescent microscopy, UV-vis-fluorescent spectroscopy, and Fourier transform infrared spectroscopy (FTIR). Increasing the monomer alkyl tail length was found to strongly increase the UV dose necessary to produce optimally blue films and fully red films. A decrease in the polymer domain size was also correlated with longer-tailed DA molecules. Metal cations have a diverse effect on the film behavior. Alkaline-earth metals such as Mg, Ca, and Ba have a negligible effect on the phase transition kinetics but can be used to tune PDA polymer domain sizes. The Ni and Fe cations increase the UV dose necessary to produce red phase PDA films and significantly decrease the polymer domain sizes. The Zn, Cd, and Cu ions exhibit strong directed interactions with the PDA carboxylic acid headgroups, resulting in quenched fluorescence and a unique film morphology. FTIR analysis provides insight into the metal-PDA binding mechanisms and demonstrates that the coordination between the PDA film headgroups and the metal cations can be correlated with changes in the film morphology and kinetics. The findings from these studies will have broad utility for tuning PDA-based sensors for different applications and sensitivity ranges.

Polyacetylene glucosides from the florets of Carthamus tinctorius and their anti-inflammatory activity

Five previously undescribed polyacetylene glucosides, namely, four C₁₀- and one C₁₄-acetylenes, together with three known analogues, were isolated from the florets of Carthamus tinctorius L. The structures of these novel compounds were elucidated to be (5R)-5-acetoxy-8,10,12-tetradecatriyne-1-O-β-D-glucopyranoside, (2Z)-decaene-4,6,8-triyne-1-O-β-D-glucopyranoside, (8Z)-1-[(3-O-β-D-glucosyl)-isovaleroyloxy]-8-decaene-4,6-diyne, (8Z)-decaene-1-isovaleroyloxy-4,6-diyne-10-O-β-D-glucopyranoside, and (2E,8E)-decadiene-4,6-diyne-1-O-β-D-glucopyranoside via spectroscopic and chemical methods. All of the isolated compounds were tested for cytotoxicity against cancer cell lines, antibacterial activity, and inhibitory effects on the lipopolysaccharide (LPS)-induced nitric oxide (NO) production. The results showed that (5R)-5-acetoxy-8,10,12-tetradecatriyne-1-O-β-D-glucopyranoside significantly inhibited LPS-induced NO production in RAW264.7 cells in a dose-dependent manner.

Unique polyacetylenic ester-neolignan derivatives from Mitrephora tomentosa and their antimalarial activities

The phytochemical investigation of the methanol extracts of the leaves and twigs of Mitrephora tomentosa Hook. f. & Thomson resulted in the isolation and identification of undescribed polyacetylenic ester-neolignan derivatives, along with six known compounds. These six undescribed natural products were named as mitrephentosins A-F. The structures of these compounds were determined by spectroscopic techniques including UV, IR, NMR, and mass spectrometric analyses. The absolute configurations of mitrephentosins A-F were determined based on specific rotations values and ECD spectral data by comparisons made with the known parent neoligan compound mitredrusin. Mitrephentosins C, E, and F showed moderate antimalarial activities (IC₅₀ values of 13.3-24.6 μM) against the Plasmodium falciparum strains TM4/8.2 and K1CB1 and were not toxic to Vero cells, while the other isolated compounds were not active against these P. falciparum strains.

Elucidation of enzymes involved in the biosynthetic pathway of bioactive polyacetylenes in Bidens pilosa using integrated omics approaches

Polyacetylene compounds from Bidens pilosa are known to have several pharmacological activities. In this study, we identified major genes encoding enzymes involved in the biosynthesis of polyacetylene in B. pilosa. Seven polyacetylene metabolites present in B. pilosa leaves were induced by methyl jasmonate (MeJA) treatment and physical wounding. Transcriptome analysis via high-throughput sequencing revealed 39 202 annotated gene fragment sequences. A DNA microarray established by the 39 202 annotated genes was used to profile gene expression in B. pilosa leaf and root tissues. As no polyacetylene compounds were found in roots, the gene expression pattern in root tissue was used as a negative control. By subtracting MeJA-induced genes in roots, we obtained 1216 genes in leaves showing an approximate three-fold increase in expression post-MeJA treatment. Nine genes encoding enzymes with desaturation function were selected for confirmation of expression by qRT-PCR. Among them, two genes, BPTC030748 and BPTC012564, were predicted to encode Δ12-oleate desaturase (OD) and Δ12-fatty acid acetylenase (FAA), respectively. In B. pilosa leaves, RNAi knock-down concomitantly decreased, while virus-mediated transient overexpression of either gene elevated polyacetylene content. In summary, we demonstrate that two important enzymes, Δ12-oleate desaturase and Δ12-fatty acid acetylenase, involved in desaturation of linear fatty acid precursors play a role in polyacetylene biosynthesis in an important medicinal plant, Bidens pilosa.

Metabolic profiling of RB-2 and RB-4, two analogs of polyacetylene from Bupleurum

RB-2 and RB-4 are two structural analogs of polyacetylene from Radix Bupleuri that show antidepressant effects. However, no metabolic data are available to elucidate their systemic homeostasis. Mass spectrometry combined with liver microsomes and recombinant drug-metabolizing enzymes were performed to profile the biotransformations of RB-2/RB-4 in vitro and in vivo. Oxidation should be the major metabolic pathways for them in phase I, while CYP2C9 and CYP2E1 was the major contributor. In phase II, conjugational groups usually combined with the metabolites from phase I. This study provides an important reference basis for the safety evaluation and rational application of RB-2/RB-4.

Quantitative seasonal variation of the falcarinol-type polyacetylene (3S)-16,17-didehydrofalcarinol and its spatial tissue distribution in Tridax procumbens

INTRODUCTION

(3S)-16,17-Didehydrofalcarinol (1) has been isolated from Tridax procumbens and has proved to have notorious bioactivity against Leishmania mexicana. In this study, hexane fractions obtained from the methanol extract of each plant part (roots, stems, leaves, flowers, and fruits) of T. procumbens collected monthly during a year were analysed in order to determine the quantity of 1 associated with biotic variables.

OBJECTIVE

The aim of this study was to find the season of the year in which the bioactive metabolite 1 is at the highest concentration and to correlate it with temperature, length of day light, and rainfall.

METHODS

Hexane fractions were obtained by liquid-liquid extraction and an accurate quantitation of 1 was performed using gas chromatography with a flame ionisation detector (GC-FID) employing pelargonic acid vanillyl amide (2) as internal standard. Partial validation was based on linearity and precision.

RESULTS

Our results indicated that the total content of 1 has significant variation (P ≤ 0.05) during the different collecting months. The total content of the metabolite reached its highest level in the roots of the plant during June in the rainfall season (0.0358 ± 0.001 mg/g), and its lowest values in February and March during the drought season (0.0015 ± 0.000 and 0.0008 ± 0.000 mg/g, respectively).

CONCLUSION

Our study provided evidence that the content of 1 in roots is strongly influenced by the variables of the harvesting season, also indicating that the biosynthesis of the active metabolite is enhanced during the warm and rainy months.

Metal Ion-Mediated Interliposomal Aggregation of Polydiacetylene Liposomes Incorporating a Phenolic Lipid

Intercolloidal behaviors mediated by metal-ligand coordination have rarely been studied. In this work, such intercolloidal behaviors were demonstrated visibly using blue-colored polydiacetylene liposomes containing a phenolic lipid that acts as a binding ligand toward metal ions. The optimized liposomes were 150-200 nm in diameter and stable in aqueous solution. In incubation tests with various neocortical metal ions, iron(III) ions produced the most obvious colloidal aggregation of the liposomes. As the pH of the incubation medium was increased from acid to basic, stronger aggregation and increased precipitation behavior were observed. The phenolic lipid is believed to contribute to the interliposomal bridging interaction, and the pH dependence of the complexation between iron(III) and the phenolic lipid inserted in the liposomes were verified.

Single polydiacetylene microtube waveguide platform for discriminating microRNA-215 expression levels in clinical gastric cancerous, paracancerous and normal tissues

MicroRNAs (miRNAs) have emerged as novel biomarkers for human early-phase cancer diagnosis and disease prevention recently. Herein, we reported a novel miRNA-215 targeting biosensor, which was based on single polydiacetylene (PDA) microtube waveguide system integrated with sandwich-type hybridization design and condensing enrichment effect. The target miRNA could be captured by oligonucleotides conjugated on the surface of PDA microtube and Au nanorod (AuNR) respectively, resulting in the out-coupled fluorescence of PDA microtube quenching. In this strategy, the formation of a sandwich structure, as a result of co-hybridization of the target miRNA, enabled simplified preparation process, enhanced reaction efficiency, and increased recyclability and stability of the platform. Based on condensing enrichment effect, the co-hybridization reaction could be enriched on the surface of microtube and the proposed platform could easily achieve highly sensitive detection of miRNA-215 in one step. Remarkably, this platform could be directly applied to discriminate the miRNA-215 expression levels in clinical gastric cancerous, paracancerous and normal tissues samples. This assay offers a simple and convenient method for miRNA quantification in clinical samples, even with the potential for invasive, portable equipment for early clinical diagnosis of diseases.

Responsive Polydiacetylene Vesicles for Biosensing Microorganisms

Polydiacetylene (PDA) inserted in films or in vesicles has received increasing attention due to its property to undergo a blue-to-red colorimetric transition along with a change from non-fluorescent to fluorescent upon application of various stimuli. In this review paper, the principle for the detection of various microorganisms (bacteria, directly detected or detected through the emitted toxins or through their DNA, and viruses) and of antibacterial and antiviral peptides based on these responsive PDA vesicles are detailed. The analytical performances obtained, when vesicles are in suspension or immobilized, are given and compared to those of the responsive vesicles mainly based on the vesicle encapsulation method. Many future challenges are then discussed.

The New Approach for Establishing the Cellular Response Guideline for Medical Applications of Polydiacetylene as Innovative Parameters

Argon plasma jet (Ar-PJ) has been widely used in clinical medicine; however, the cellular effects of Ar-PJ therapy applying to living tissues have not been clarified yet. It is necessary to investigate cellular responses to Ar-PJ in establishing guidelines on the therapeutic use of Ar-PJ. Interestingly, in the Ar-PJ-treated cells, the fragmented mitochondria, a typical cellular stress indicator, were discovered even in the cells located in the live zones (1∼3 zones). Using microscopic measurements of the mitochondrial length, we found that the fragmented mitochondria were mainly in the zones 1 and 2, the closest to the direct exposure point of Ar-PJ. Whereas, the mitochondria in the zone 4 retained their lengths to normal. This quantitative measurement of mitochondrial morphology was combined with the color scores of the polymerizable supramolecular (PS) sensor in diagnostic categories. The results demonstrate that the mitochondrial length (0.98∼3.94 μm) is inversely proportional to the PS sensor color scores (87∼0) in the zones 1∼4. On the combination of these three diagnostic parameters, the effective range of Ar-PJ for cellular responses was determined: the zones 1∼3, the color scores 87∼12 and the mitochondrial lengths 0.98∼2.57 μm. Our study is the first demonstration of mitochondrial fragmentation in response to Ar-PJ and the first attempt to establish the diagnostic guideline for Ar-PJ therapies by combinations with biological, physical and chemical aspects. Thus, this study will make great advances in the field of bioplasma applications.

Polydiacetylenic nanofibers as new siRNA vehicles for in vitro and in vivo delivery

Polydiacetylenic nanofibers (PDA-Nfs) obtained by photopolymerization of surfactant 1 were optimized for intracellular delivery of small interfering RNAs (siRNAs). PDA-Nfs/siRNA complexes efficiently silenced the oncogene Lim-1 in the renal cancer cells 786-O in vitro. Intraperitoneal injection of PDA-Nfs/siLim1 downregulated Lim-1 in subcutaneous tumor xenografts obtained with 786-O cells in nude mice. Thus, PDA-Nfs represent an innovative system for in vivo delivery of siRNAs.

Biomolecule-Functionalized Smart Polydiacetylene for Biomedical and Environmental Sensing

Polydiacetylene (PDA) has attracted interest for use as a sensing platform in biomedical, environmental, and chemical engineering applications owing to its capacity for colorimetric and fluorescent transition in response to external stimuli. Many researchers have attempted to develop a tailor-made PDA sensor via conjugation of chemical or biological substances to PDA. Here, we review smart bio-conjugates of PDA with various biomolecules such as carbohydrates, lipids, nucleic acids, and proteins. In addition, materialization and signal amplification strategies to improve handling and sensitivity are described.

Selective and sensitive detection of MiRNA-21 based on gold-nanorod functionalized polydiacetylene microtube waveguide

Development of rapid, highly selective and sensitive miRNA detection in a complex biological environment has attracted considerable attention. Herein, we describe a novel two step method to construct gold-nanorod functionalized polydiacetylene (PDA) microtube for miRNA detection. In PDA microtube, with a one-dimensional (1D) waveguide nature, the excitation position and emission out-coupling position are far apart, thus helpful in reducing contribution of auto-fluorescence from biological sample. The use of specially designed toehold-mediated strand displacement reaction enables the reliable and selective discrimination of miRNA sequences with high sequence homology. Based on the condensing enrichment effect, the detection limit of the proposed PDA microtube system is as low as 0.01nM, and it can be applied directly to detect disease-specific miRNA targets in human serum. This PDA microtube waveguide system can be further integrated into the chip for the potential applications in minimally invasive, portable clinical diagnostic equipment.

Photopatterned Polydiacetylene Images Using a DNA Bio-Photomask

We describe a novel strategy to fabricate a well-defined polydiacetylene (PDA) supramolecular pattern on polyvinylidene fluoride (PVDF) membrane utilizing a DNA bio-photomask. By focusing on that, the absorption spectrum of DNA molecules having a λmax at 260 nm overlaps with the wavelength at which the photopolymerization of the diacetylene monomer occurs, DNA molecules are used to define specific patterns on PVDF membranes coated with diacetylene lipids by shielding the applied 254 nm UV light and consequently preventing the photopolymerization of the lipids. As a result, the DNA-covered regions retain the original white color on the membrane while the regions uncovered by DNA molecules undergo the color change to blue through the photopolymerization by 254 nm UV irradiation. On the basis of the selective illumination through a DNA photomask, we precisely manufacture specific patterns using a microarray spotting method and also demonstrate the capability of this strategy to achieve a novel colorimetric DNA sensor without any complicated process.

A Magnetically Responsive Polydiacetylene Precursor for Latent Fingerprint Analysis

A magnetically responsive diacetylene (DA) powder was developed for the visualization of latent fingerprints. A mixture of the DA and magnetite nanoparticles, applied to a surface containing latent fingermarks, becomes immobilized along the ridge patterns of the fingerprints when a magnetic field is applied. Alignment along the ridge structures is a consequence of favorable hydrophobic interactions occurring between the long alkyl chains in the DAs and the lipid-rich, sebaceous latent fingermarks. UV irradiation of the DA-magnetite composite immobilized on the latent fingerprint results in the generation of blue-colored PDAs. Heat treatment of the blue-colored image promotes a blue-to-red transition as well as fluorescence turn-on. A combination of the aligned pale brown-colored monomeric state, UV irradiation generated blue-colored PDA state, as well as the heat treatment generated red-colored and fluorescent PDA state enables efficient visual imaging of a latent fingerprint, which is deposited on various colored solid surfaces.

Direct observation by using Brewster angle microscopy of the diacetylene polimerization in mixed Langmuir film

Mixed Langmuir monolayers of 10,12-Pentacosadiynoic acid (DA) and amphiphilic hemicyanine (HSP) have been fabricated at the air-water interface. The mixed monolayer has been proved to be completely homogeneous. The DA molecules are arranged in a single monolayer within the mixed Langmuir monolayer, as opposed to the typical trilayer architecture for the pure DA film. Brewster angle microscopy has been used to reveal the mesoscopic structure of the mixed Langmuir monolayer. Flower shape domains with internal anisotropy due the ordered alignment of hemicyanine groups have been observed. Given the absorption features of the hemicyanine groups at the wavelength used in the BAM experiments, the enhancement of reflection provoked by the absorption process leads to the observed anisotropy. The ordering of such groups is promoted by their strong self-aggregation tendency. Under UV irradiation at the air-water interface, polydiacetylene (PDA) has been fabricated. In spite a significant increase in the domains reflectivity has been observed owing to the modification in the mentioned enhanced reflection, the texture of the domains remains equal. The PDA polymer chain therefore grows in the same direction in which the HSP molecules are aligned. This study is expected to enrich the understanding and design of fabrication of PDA at interfaces.

Optimization of Polydiacetylene-Coated Superparamagnetic Magnetite Biosensor for Colorimetric Detection of Biomarkers

Biosensors for point-of-care testing of critical illnesses are urgently needed, especially in many areas of poor healthcare infrastructure. Polydiacetylene-based sensors are ideal because of their unique colorimetric properties where blue to red color shifts can be observed with the naked eye. In this work, a colorimetric biosensor capable of simple, rapid magnetic separation is optimized, using horse IgG as a model antibody, to obtain higher sensitivity. Composed of a unique combination of polydiacetylene and superparamagnetic iron oxide, the biosensor is fabricated at varying ratios of polydiacetylene to demonstrate optimization of color responsiveness. At increasing polydiacetylene ratios, improved color responsiveness and aqueous dispersion are observed, but the magnetic separation efficiency starts to suffer. The optimal color response is obtained at 90 wt% polydiacetylene. In addition, a 50 times improved lower detection limit of 0.01 mg/mL horse IgG is achieved, a relevant biomarker concentration for diagnosing sepsis. This platform provides a promising colorimetric biosensor for point-of-care use.

Polydiacetylene nanovesicles as carriers of natural phenylpropanoids for creating antimicrobial food-contact surfaces

The ultimate goal of this study was developing antimicrobial food-contact materials based on natural phenolic compounds using nanotechnological approaches. Among the methyl-β-cyclodextrin-encapsulated phenolics tested, curcumin showed by far the highest activity toward Escherichia coli with a minimum inhibitory concentration of 0.4 mM. Curcumin was enclosed in liposome-type polydiacetylene/phosholipid nanovesicles supplemented with N-hydroxysuccinimide and glucose. The fluorescence spectrum of the nanovesicles suggested that curcumin was located in their bilayer region. Free-suspended nanovesicles tended to bind to the bacterial surface and demonstrated bactericidal activity toward Gram-negative (E. coli) and vegetative cells of Gram-positive (Bacillus cereus) bacteria reducing their counts from 5 log CFU mL(-1) to an undetectable level within 8 h. The nanovesicles were covalently bound to silanized glass. Incubation of E. coli and B. cereus with nanovesicle-coated glass resulted in a 2.5 log reduction in their counts. After optimization this approach can be used for controlling microbial growth, cross-contamination, and biofilm formation on food-contacting surfaces.

Robust polydiacetylene-based colorimetric sensing material developed with amyloid fibrils of α-synuclein

Robust polydiacetylene-based colorimetric sensing material has been developed with amyloid fibrils of α-synuclein in the presence of 10,12-pentacosadiynoic acid (PCDA) by taking advantage of the specific fatty acid interaction of α-synuclein and structural regularity of the self-assembled product of amyloid fibrils. PCDA facilitated not only self-oligomerization of α-synuclein but also its fibrillation into the fibrils with increased thickness. Upon UV irradiation, the PCDA-containing amyloid fibrils (AF-PCDAs) turned blue, which then became red following heat treatment. The blue-to-red color transition was also observed with other stimuli of pH and ethanol. AF-PCDAs were demonstrated to be mechanically stable since not only the individual colors of blue and red but also their colorimetric transition were not affected by a number of sonications which readily disrupted the polydiaceylene (PDA) vesicles with the instant loss of color. Therefore, AF-PCDA can be considered to be a novel PDA-based colorimetric sensing material with high mechanical strength, which has the potential to be employed in various areas involving advanced sensing technologies.

The influence of amino acid sequence on structure and morphology of polydiacetylene containing peptide fibres

A systematic study was performed on the influence of charge and steric hindrance on the assembly into fibres of a series of pentameric peptides based on the well-known β-sheet forming sequence Gly-Ala-Gly-Ala-Gly, which were N-terminally acylated with pentacosadiynoic acid. To investigate the effect of steric hindrance and charge repulsion on the fibre structure, either the N-terminal or the C-terminal amino acid in the sequence was replaced by a glutamic acid or lysine residue. Furthermore, peptide amphiphiles (PAs) with an amide or a free acid group at the C-terminus were compared. Steric hindrance and charge repulsion were addressed individually by varying the pH during and after fibre preparation. The self-assembled structures were examined with circular dichroism (CD) spectroscopy and transmission electron microscopy (TEM). UV spectroscopy was used to probe the diacetylene packing in the hydrophobic tail, both by polymerisation behaviour and chromatic properties of the polymers. In brief, the assembly was hindered more if the modification was close to the alkyl tail, and glutamic acid brought about a larger effect than lysine. PAs with two charges yielded assemblies which after polymerisation were found to be the most susceptible towards changes in pH, behaving as a colour-based pH sensor. Typically, TEM and UV showed the same trends, indicating that a distorted morphology as observed with TEM is indicative of a poorer molecular packing of the peptide amphiphile fibres, probed via the changes in absorption of the polydiacetylene backbone.

Magainin II modified polydiacetylene micelles for cancer therapy

Polydiacetylene (PDA) micelles have been widely used to deliver anticancer drugs in the treatment of a variety of tumours and for imaging living cells. In this study, we developed an effective strategy to directly conjugate magainin II (MGN-II) to the surface of PDA micelles using a fluorescent dye. These stable and well-defined PDA micelles had high cytotoxicity in cancer cell lines, and were able to reduce the tumour size in mice. The modified PDA micelles improved the anticancer effects of MGN-II in the A549 cell line only at a concentration of 16.0 μg mL(-1) (IC50). In addition, following irradiation with UV light at 254 nm, the PDA micelles gave rise to an energy transfer from the fluorescent dye to the backbone of PDA micelles to enhance the imaging of living cells. Our results demonstrate that modified PDA micelles can not only be used in the treatment of tumors in vitro and in vivo in a simple and directed way, but also offer a new platform for designing functional liposomes to act as anticancer agents.

Application of PCDA/SPH/CHO/Lysine vesicles to detect pathogenic bacteria in chicken

During the course of infection, Salmonella must successively survive the harsh acid stress of the stomach and multiply into a mild acidic compartment within macrophages. Inducible amino acid decarboxylases are known to promote adaptation to acidic environments, as lysine decarboxylation to cadaverine. The idea of Salmonella defenses responses could be employed in systems as polydiacetylene (PDA) to detect this pathogen so important to public health system. Beside that PDA is an important substance because of the unique optical property; that undergoes a colorimetric transitions by various external stimuli. Therefore 10,12-pentacosadyinoic acid (PCDA)/Sphingomyelin(SPH)/Cholesterol(CHO)/Lysine system was tested to determine the colorimetric response induced by Salmonella choleraesuis. PCDA/SPH/CHO/Lysine vesicles showed a colour change even in low S. choleraesuis concentration present in laboratory conditions and in chicken meat. Thus, this work showed a PCDA/SPH/CHO/Lysine vesicle application to simplify routine analyses in food industry, as chicken meat industry.

Polarized fluorescence microscopy analysis of patterned, polymerized perfluorotetradecanoic acid-pentacosadiynoic acid thin films

Photoillumination of mixed films comprised of the photopolymerizable fatty acid 10,12 pentacosadiynoic acid and perfluorotetradecanoic acid deposited onto glass substrates gives rise to the formation of oriented polydiacetylene photopolymer fibers. The degree of polymer fiber orientation was investigated using dual-view, polarized fluorescence microscopy of the polydiacetylene, which allowed for characterization of individual fluorescent polymer fibers after photopolymerization, as well as comparison of the orientation of different fibers within the same sample. Measurements indicated that individual fibers consisted of multiple photopolymer strands with various orientations, and that there was a preferred orientation for fibers in the film as a whole. The fibers were preferentially oriented at an angle of approximately 60° to the direction of film compression during deposition from a Langmuir trough, with orientation being the result of mechanical stress exerted by the compression barriers coupled with rotation of the polymer fibers during film draining. These measurements were complemented with conventional "bulk" fluorescence polarization experiments, and compared with mixed film structures described previously for these systems at the air-water interface using Brewster angle microscopy.

Dual-mode optical sensing of organic vapors and proteins with polydiacetylene (PDA)-embedded electrospun nanofibers

Optical sensors capable of colorimetric visualization and/or fluorescence detection have shown tremendous potential for field technicians and emergency responders, owing to the portability and low cost of such devices. Polydiacetylene (PDA)-enhanced nanofibers are particularly promising due to high surface area, facile functionalization, simple construction, and the versatility to empower either colorimetric or fluorescence signaling. We demonstrate here a dual-mode optical sensing with electrospun nanofibers embedded with various PDAs. The solvent-dependent fluorescent transition of nanofibers generated a pattern that successfully distinguished four common organic solvents. The colorimetric and fluorescent sensing of biotin-avidin interactions by embedding biotinylated-PCDA monomers into silica-reinforced nanofiber mats were realized for detection of biomolecules. Finally, a PDA-based nanofiber sensor array consisting of three monomers has been fabricated for the determination and identification of organic amine vapors using colorimetry and principal component analysis (PCA). The combination of PCA and the strategy of probing analytes in two different concentration ranges (ppm and ppth) led to successful analysis of all eight amines.

Janus-compartmental alginate microbeads having polydiacetylene liposomes and magnetic nanoparticles for visual lead(II) detection

Janus-compartmental alginate microbeads having two divided phases of sensory polydiacetylene (PDA) liposomes and magnetic nanoparticles were fabricated for facile sensory applications. The sensory liposomes are composed of PDA for label-free signal generation and 1,2-dipalmitoyl-sn-glycero-3-galloyl (DPGG) lipids whose galloyl headgroup has specific interactions with lead(II). The second phase having magnetic nanoparticles is designed for convenient handling of the microbeads, such as washing, solvent exchange, stirring, and detection, by applying magnetic field. Selective and convenient colorimetric detection of lead(II) and efficient removal of lead(II) by alginate matrix at the same time are demonstrated.

Poly(methyl methacrylate)-supported polydiacetylene films: unique chromatic transitions and molecular sensing

Polydiacetylenes (PDAs) constitute a family of conjugated polymers exhibiting unique colorimetric and fluorescence transitions, and have attracted significant interest as chemo- and biosensing materials. We spin-coated PDA films upon poly(methyl methacrylate) (PMMA), and investigated the photophysical properties and sensing applications of the new PDA configuration. Specifically, the as-polymerized blue PDA layer underwent distinct transformations to purple, red, and yellow phases, which could be quantified through conventional color scanning combined with application of image analysis algorithms. Furthermore, we recorded a reversible red-purple PDA transition that was induced by ultraviolet irradiation, a phenomenon that had not been reported previously in PDA film systems. We show that distinct color and fluorescence transitions were induced in the PMMA-supported PDA films by amphiphilic substances-surfactants and ionic liquids-and that the chromatic transformations were correlated to the analyte structures and properties. Overall, this study presents a new chromatic PDA film system in which noncovalent interactions between the PMMA substrate and spin-coated PDA give rise to distinct chromatic properties and molecular sensing capabilities.

Polydiacetylene-based high-throughput screen for surfactin producing strains of Bacillus subtilis

Although traditional mutation is still an attractive approach for strain improvement, it is tedious, time-consuming, and inefficient to screen for surfactin producing strains. To overcome this, we developed a high-throughput screening method for surfactin producing mutants by applying polydiacetylene (PDA) vesicles as sensors with visible chromatic change from blue to red, detected as colorimetric response (CR%) signal, which can even semi-quantify the yields of surfactin. Bacillus subtilis 723 was used as parent strain and multiply mutated with atmospheric and room temperature plasma (ARTP). Mutants were cultured in MicroFlask by Duetz (24 square deepwell plates, Applikon Biotechnology) and surfactin titers were tested in 96-well plates with PDA vesicles. Mutants with surfactin titers above150 mg/L (CR% value above 26%) were selected as high-yield strains and further quantified by HPLC. By integrating MicroFlask cultivation and the PDA vesicles detection, we screened 27,000 mutants and found 37 high-yield strains. From these, one mutant produced 473.6 mg/L surfactin (including 353.1 mg/L C15 surfactin), which was 5.4-fold than that of the parent strain. This method is efficient, cost-effective and provides wider application in screening for various surfactants.

Naked eye screening of 11 phenolic compounds and colorimetric determination using polydiacetylene vesicles with α-cyclodextrin

The colorimetric response (CR) of poly(10,12-pentacosadiynoic acid) vesicles (PPCDA) induced by α-cyclodextrin (α-CD) in an aqueous solution has been studied. Various parameters affecting the CR, such as response time and concentration were investigated. The blue color of 0.01 mM PPCDA solution became pinkish red with the addition of α-CD at the concentration higher than 3 mM. The inhibition of the color transition from blue to red was investigated using 11 phenolic compounds. The color transition could be inhibited and observed by naked eye in the presence of 4 phenolic compounds, i.e. 4-nitrophenol (4-NP) and 4-bromophenol (4-BP) and 4-chlorophenol (4-CP) and 3-nitrophenol (3-NP). A colorimetric method for the determination of these compounds was validated and applied for surface water analysis. The linear range from the plot of CR against phenolic compounds concentration was in the order of 0.5-2.0 mM with R(2) more than 0.99. The recoveries were 90-95% with good precision (1-4%RSD, n=10).

Polydiacetylenes bearing boronic acid groups as colorimetric and fluorescence sensors for cationic surfactants

A new polydiacetylene oxyphenylboronic acid (PDA-OPBA-1) bearing group was synthesized and showed diverse colorimetric changes, such as yellow, orange, and red, upon the addition of cationic surfactants at pH 7.4. On the other hand, anionic surfactants and simple ammonium salts did not show any color change. Specifically, color changes to yellow for cetyl trimethylammonium chloride (CTAC), red for dodecyl trimethylammonium bromide (DTAB), orange for benzylcetyldimethylammonium chloride (BCDA), and dark orange for hexadecylpyridium bromide (HDPB) are observed, respectively. Different head groups and alkyl chain lengths of cationic surfactants can be intelligently distinguished via a unique penetration process.

Inkjet-compatible single-component polydiacetylene precursors for thermochromic paper sensors

Inkjet-printable diacetylene (DA) supramolecules, which can be dispersed in water without using additional surfactants, have been developed. The supramolecules are generated from DA monomers that contain bisurea groups, which are capable of forming hydrogen-bonding networks, and hydrophilic oligoethylene oxide moieties. Because of suitable size distribution and stability characteristics, the single DA component ink can be readily transferred to paper substrates by utilizing a common office inkjet printer. UV irradiation of the DA-printed paper results in generation of blue-colored polydiacetylene (PDA) images, which show reversible thermochromic transitions in specific temperature ranges. Inkjet-printed PDAs, in the format of a two-dimensional (2D) quick response (QR) code on a real parking ticket, serve as a dual anticounterfeiting system that combines easy decoding of the QR code and colorimetric PDA reversibility for validating the authenticity of the tickets. This single-component ink system has great potential for use in paper-based devices, temperature sensors, and anticounterfeiting barcodes.