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Abstract: A novel ultra‐low‐cost biochemical analysis platform to quantify protein dissociation binding constants and kinetics using paper microfluidics is reported. This approach marries video imaging with one of humankind's oldest materials: paper, requiring no large, expensive laboratory equipment, complex microfluidics or external power. Temporal measurements of nanoparticle–antibody conjugates binding on paper is found to follow the Langmuir Adsorption Model. This is exploited to measure a series of antibody–antigen dissociation constants on paper, showing excellent agreement with a gold‐standard benchtop interferometer. The concept is demonstrated with a camera and low‐end smartphone, 500‐fold cheaper than the reference method, and can be multiplexed to measure ten reactions in parallel. These findings will help to widen access to quantitative analytical biochemistry, for diverse applications spanning disease diagnostics, drug discovery, and environmental analysis in resource‐limited settings. [ABSTRACT FROM AUTHOR]

To circumvent the bottlenecks of non-flexibility, low sensitivity, and narrow workable detection range of conventional biosensors for biological molecule detection (e.g., dopamine (DA) secreted by living cells), a new hybrid flexible electrochemical biosensor has been created by decorating closely packed dendritic Pt nanoparticles (NPs) on freestanding graphene paper. This innovative structural integration of ultrathin graphene paper and uniform 2D arrays of dendritic NPs by tailored wet chemical synthesis has been achieved by a modular strategy through a facile and delicately controlled oil-water interfacial assembly method, whereby the uniform distribution of catalytic dendritic NPs on the graphene paper is maximized. In this way, the performance is improved by several orders of magnitude. The developed hybrid electrode shows a high sensitivity of 2 μA cm−2 μ m−1, up to about 33 times higher than those of conventional sensors, a low detection limit of 5 n m, and a wide linear range of 87 n m to 100 μ m. These combined features enable the ultrasensitive detection of DA released from pheochromocytoma (PC 12) cells. The unique features of this flexible sensor can be attributed to the well-tailored uniform 2D array of dendritic Pt NPs and the modular electrode assembly at the oil-water interface. Its excellent performance holds much promise for the future development of optimized flexible electrochemical sensors for a diverse range of electroactive molecules to better serve society. [ABSTRACT FROM AUTHOR]

Abstract: Diarylethene derivatives, the biological activity of which can be reversibly changed by irradiation with light of different wavelengths, have shown promise as scientific tools and as candidates for photocontrollable drugs. However, examples demonstrating efficient photocontrol of their biological activity are still relatively rare. This concept article discusses the possible reasons for this situation and presents a critical analysis of existing data and hypotheses in this field, in order to extract the design principles enabling the construction of efficient photocontrollable diarylethene‐based molecules. Papers addressing biologically relevant interactions between diarylethenes and biomolecules are analyzed; however, in most published cases, the efficiency of photocontrol in living systems remains to be demonstrated. We hope that this article will encourage further discussion of design principles, primarily among pharmacologists, synthetic and medicinal chemists. [ABSTRACT FROM AUTHOR]

Confinement of reactive chemical species uniquely affects chemical reactivity by restricting the physical space available and by restricting access to interactions with the solvent. In Nature, for example, confined protein binding pockets govern processes following photoisomerization reactions and the isomerizations themselves. Here we describe the first example of a dihydroazulene/vinylheptafulvene (DHA/VHF) photo-switch functioning in water, and we show how its switching behavior is strongly influenced by supramolecular interactions with a series of cucurbit[ n]uril (CB) host molecules. In CB7 inclusion complexes, the kinetics of the thermal VHF-to-DHA back-reaction is accelerated, while in CB8 inclusion complexes, the kinetics is slowed down as compared to the free photo-switch. The effect of the CB encapsulation of the photo-switch can be effectively canceled by introducing a guest that binds the CB more strongly. According to DFT calculations, a stabilization of the reactive s- cis VHF conformer relative to the s- trans VHF appears to be a contributing factor responsible for the accelerated back-reaction when encapsulated in CB7. [ABSTRACT FROM AUTHOR]

Supramolecular hydrogels obtained by combining 5′-adenosine monophosphate (AMP) with Ag+ were fabricated in this work. Their gelation capability was enhanced by increasing the concentration of Ag+ or decreasing the pH. The gels are very sensitive to light, which endows them with potential applications as visible-light photosensitive materials. Coordination between the nucleobase of AMP and Ag+, as well as π-π stacking of nucleobases, are considered to be the main driving forces for self-assembly. The hydrogels successfully achieved the encapsulation and enrichment of biomolecules. Hydrogen bonding between the amino group of guest molecules and silver nanoparticles along the nanofibers drives the enrichment and is considered to be a crucial interaction. [ABSTRACT FROM AUTHOR]

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Supramolecular hydrogels with tunable properties have innovative applications in biomedicine, catalysis, and materials chemistry. Minimalist low-molecular-weight hydrogelators based on squaramide and squaramic acid motifs have been designed. This approach benefits from the high acidity of squaramic acids and the aromaticity of squaramides. Moreover, substituents on the aryl ring tune the π density of the arylsquaramide motif. Thus, materials featuring distinct thermal and mechanical properties have been successfully prepared. The hydrogel ( G′≈400 Pa, G′′≈57 Pa; at 1.0 % w/v; 1 Hz) obtained from 4-nitrophenylsquaramide motif 1 is thermoreversible ( T=57 °C at 0.2 % w/v), thixotropic, self-healable, and undergoes irreversible shrinking in response to saline stress. Furthermore, the hydrogel is injectable and can be loaded with substantial amounts (5:1 excess molar ratio) of zwitterionic biomolecules, such as l-carnitine, γ-aminobutyric acid (GABA), or d,l-Ala- d,l-Ala, without any loss of structural integrity. Then, the release of these molecules can be modulated by saline solutions. [ABSTRACT FROM AUTHOR]

Triplex-forming peptide nucleic acids (TFPNAs) were targeted to double-helical regions of 19F-labeled RNA hairpin models (a UA-rich duplex with a hexaethylene glycol (heg) loop and a microRNA model, miR-215). In addition to conventional UV- and circular dichroism (CD)-based detection, binding was monitored by 19F NMR spectroscopy. Detailed information on the stoichiometry and transition between the triple-helical peptide nucleic acid (PNA)/RNA and (PNA)2/RNA binding modes could be obtained. γ-( R)-Hydroxymethyl-modified thymine-1-yl- and 2-aminopyridin-3-yl-acetyl derivatives of TFPNAs were additionally synthesized, which were targeted to the same RNA models, and the effect of the γ-( R)-hydroxymethyl group on binding was studied. An appropriate pattern of γ-( R)-hydroxymethyl modifications reduced the stability of the ternary complex and preferred stoichiometric binding to the miR-215 model. [ABSTRACT FROM AUTHOR]

Expansion microscopy (ExM) has been widely used to detect biomolecules in cultured cells and tissue samples due to its enablement of super resolution imaging with conventional microscopes, via physical expansion of samples. However, reaction conditions inherent to the process bring about strong fluorescent signal loss during polymerization and digestion and thus limit the brightness of the signal obtained post expansion. Here, we explore the impact of stabilizer‐containing organic fluorophores in ExM, as a mitigation strategy for this radical‐induced dye degradation. Through direct conjugation of 4‐nitrophenylalanine (NPA) to our previously developed trifunctional reagents, we validate and demonstrate that these multifunctional linkers enable visualization of different organelles with improved fluorescent intensity, owning to protection of the dyes to radical induced degradation as well as to photoprotection upon imaging. At this point, we cannot disentangle the relative contribution of both mechanisms. Furthermore, we report anchoring linkers that allow straightforward application of NPA or Trolox to commercially available fluorophore‐conjugated antibodies. We show that these anchoring linkers enable complete retention of biological targets while increasing fluorophore photostability. Our results provide guidance in exploring these stabilizer‐modified agents in ExM and methods for increased signal survival through the polymerization steps of the ExM protocols. [ABSTRACT FROM AUTHOR]

The threading of biomolecules through pores or channels in membranes is important to validate the physiological activities of cells. To aid understanding of the controlling factors required for the translocation in space with confined size and distorted conformation, it is desirable to identify experimental systems with minimized complexity. We demonstrate the mechanism of a linear guest L1 threading into a tris(crown ether) host TC with a combinational distorted cavity to form a triply interlocked [2]pseudorotaxane 3in-[ L1⊂ TC]. An inchworm-motion mechanism is proposed for the process. For the forward-threading steps that lead to the formation of higher-order interlocked species, guest L1 must adopt a bent conformation to find the next crown ether cavity. Two simplified models are applied to investigate the self-assembly dynamic of 3in-[ L1⊂ TC]. Kinetic NMR spectroscopic and molecular dynamics (MD) studies show that formation of the singly penetrated species is fast, whereas formation of the doubly and triply threaded species is several orders of magnitude slower. During threading the freedom of both the guest L1 and host TC gradually decrease due to their interactions. This results in a significant entropy effect for the threading dynamic, which is also observed for the threading of a biomolecular chain through a channel. [ABSTRACT FROM AUTHOR]

The requirement for nitric oxide (NO) of lysosomes has motivated the development of a sophisticated fluorescent probe to monitor the distribution of this important biomolecule at the subcellular level in living cells. A near-infrared (NIR) fluorescent Si-rhodamine (SiRB)-NO probe was designed based on the NO-induced ring-opening process of Si-rhodamine. The probe exhibits fast chromogenic and fluorogenic responses, and high sensitivity and selectivity toward trace amounts of NO. Significantly, the spirolactam in Si-rhodamine exhibits very good tolerance to H+, which in turn brings extremely low background fluorescence not only in the physiological environment but also under acidic conditions. The stability of the highly fluorescent product in acidic solution provides persistent fluorescence emission for long-term imaging experiments. To achieve targeted imaging with improved spatial resolution and sensitivity, an efficient lysosome-targeting moiety was conjugated to a SiRB-NO probe, affording a tailored lysosome-targeting NIR fluorescent Lyso-SiRB-NO probe. Inheriting the key advantages of its parent SiRB-NO probe, Lyso-SiRB-NO is a functional probe that is suited for monitoring lysosomal NO with excellent lysosome compatibility. Imaging experiments demonstrated the monitoring of both exogenous and endogenous NO in real time by using the Lyso-SiRB-NO probe. [ABSTRACT FROM AUTHOR]

The interfacial properties of solid substrates are of importance for protein adsorption. Herein, we report a reversible protein adsorption switch based on the host-guest interaction of the butoxy pillar[5]arene and adipic acid. By the detector of the contact angle (CA), atomic force microscopy (AFM), and luminoscope on the silicon substrate, the intelligent protein switch exhibits excellent adsorptivity for BSA and switch performance by pH regulation. [ABSTRACT FROM AUTHOR]

The inhibition of the G protein-coupled receptor, relaxin family peptide receptor 1 (RXFP1), by a small LDLa protein may be a potential approach for prostate cancer treatment. However, it is a significant challenge to chemically produce the 41-residue and three-disulfide cross-bridged LDLa module which is highly prone to aspartimide formation due to the presence of several aspartic acid residues. Known palliative measures, including addition of HOBt to piperidine for Nα-deprotection, failed to completely overcome this side reaction. For this reason, an elegant native chemical ligation approach was employed in which two segments were assembled for generating the linear LDLa protein. Acquisition of correct folding was achieved by using either a regioselective disulfide bond formation or global oxidation strategies. The final synthetic LDLa protein obtained was characterized by NMR spectroscopic structural analysis after chelation with a Ca2+ ion and confirmed to be equivalent to the same protein obtained by recombinant DNA production. [ABSTRACT FROM AUTHOR]

Artificially synthesized stimuli‐responsive biomolecules are attractive as molecular tools for monitoring and modulating biological systems. In biological systems, redox stimuli are common, and their dysregulation is typically linked to various abnormal or disease states. In this Concept article, the molecular design of reduction‐responsive biomolecules, such as peptides, nucleic acids, and saccharides, which are produced by introducing nitroaryl groups into them, is reviewed with a special emphasis on simple 4‐nitrobenzene‐based motifs. [ABSTRACT FROM AUTHOR]

A series of cationic and neutral p−Br and p−NO2 pyridine substituted Eu(III) and Gd(III) coordination complexes serve as versatile synthetic intermediates. Nucleophilic aromatic substitution occurs readily at the para position under mild conditions, allowing C−N and C−C bond forming reactions to take place, permitting the introduction of azide, amino and alkynyl substituents. For Eu(III) complexes, this approach allows late stage tuning of absorption and emission spectral properties, exemplified by the lowering of the energy of an LMCT transition accompanied by a reduction in the Eu−Npy bond length. Additionally, these complexes provide direct access to the corresponding Eu(II) analogues. With the Gd(III) series, the nature of the p‐substituent does not significantly change the EPR properties (linewidth, relaxation times), as required for their development as EPR spin probes that can be readily conjugated to biomolecules under mild conditions. [ABSTRACT FROM AUTHOR]

Herein is reported a circularly polarized luminescent (CPL) probe that can respond to the chirality of nucleic acids. An achiral nanostructure was prepared by the hybridization of symmetric serinol nucleic acid (SNA) containing pyrene‐modified residues. When chiral oligomers that were complementary to the SNA were added, they induced helicity into the SNA nanowire. Efficient circular dichroism (CD) signal amplification was observed when pyrene was attached to uracil bases through a rigid alkynyl linker. Both CPL and CD signals were observed; they depended on the chirality of the added acyclic threoninol nucleic acid (aTNA) oligomer. This system can be used to convert the chirality of chiral biomolecules into chiroptical signals. [ABSTRACT FROM AUTHOR]

Cover Feature: Versatile Bispidine-Based Bifunctional Chelators for 64CuII-Labelling of Biomolecules (Chem. Eur. J. 9/2020) Reductive alkylation at the relatively inert C9-position of bispidols paves the way for generating a number of derivatives ready to be coupled to a variety of targeting vector molecules. As these bispidine derivatives form highly stable complexes with the positron emitter SP 64 sp Cu SP II sp , they are virtually predestined for their application in the field of diagnostic positron emission tomography (PET). [Extracted from the article]

Structural analysis of modern pharmaceutical practices allows for the identification of two rapidly growing trends: the introduction of tailor‐made amino acids and the exploitation of fluorinated motifs. Curiously, the former represents one of the most ubiquitous classes of naturally occurring compounds, whereas the latter is the most xenobiotic and comprised virtually entirely of man‐made derivatives. Herein, 39 selected compounds, featuring both of these traits in the same molecule, are profiled. The total synthesis, source of the corresponding amino acids and fluorinated residues, and medicinal chemistry aspects and biological properties of the molecules are discussed. [ABSTRACT FROM AUTHOR]

The two enantiomers of a compound often have profoundly different biological properties and thus their liability to racemisation in aqueous solutions is an important piece of information. The authors reviewed the available data concerning the process of racemisation in vivo, in the presence of biological molecules (e.g., racemase enzymes, serum albumin, cofactors and derivatives) and under purely chemical but aqueous conditions (acid, base and other aqueous systems). Mechanistic studies are described critically in light of reported kinetic data. The types of experimental measurement that can be used to effectively determine rate constants of racemisation in various conditions are discussed and the data they provide is summarised. The proposed origins of enzymatic racemisation are presented and suggest ways to promote the process that are different from processes taking place in bulk water. Experimental and computational studies that provide understanding and quantitative predictions of racemisation risk are also presented. [ABSTRACT FROM AUTHOR]

Bifunctional chelators as parts of modular metal‐based radiopharmaceuticals are responsible for stable complexation of the radiometal ion and for covalent linkage between the complex and the targeting vector. To avoid loss of complex stability, the bioconjugation strategy should not interfere with the radiometal chelation by occupying coordinating groups. The C9 position of the very stable CuII chelator 3,7‐diazabicyclo[3.3.1]nonane (bispidine) is virtually predestined to introduce functional groups for facile bioconjugation as this functionalisation does not disturb the metal binding centre. We describe the preparation and characterisation of a set of novel bispidine derivatives equipped with suitable functional groups for diverse bioconjugation reactions, including common amine coupling strategies (bispidine‐isothiocyanate) and the Cu‐free strain‐promoted alkyne–azide cycloaddition. We demonstrate their functionality and versatility in an exemplary way by conjugation to an antibody‐based biomolecule and validate the obtained conjugate in vitro and in vivo. [ABSTRACT FROM AUTHOR]

Multivalent interactions between more than one interconnected biomolecule are easily found in diverse natural systems. With the cooperation of many interacting pairs, this clustered binding can achieve highly enhanced affinities. Whereas the binding of an individual pair remains reversible, the binding between multivalent biomolecules can become nearly irreversible. Although the underlying principles of the multivalent effect have yet to be revealed, this intriguing concept of multivalent interaction has been widely applied to diverse fields. Multivalency has become a key strategy to increase the potency of inhibitors against target pathogens and, more recently, enhanced target binding by multivalency has offered an attractive strategy for biosensing. In this article, the current status of multivalent interaction studies and their progress in the biosensing area will be discussed. Enhance your senses! Multivalent interactions provide greatly increased binding affinities, which can be applied for biosensors with enhanced sensitivity. Recent studies also suggested that sensing selectivity may also be improved by using multivalent interactions between targets and capturing probes (see figure). [ABSTRACT FROM AUTHOR]

Therapeutic nanoreactors have been proposed as nanoplatforms to treat diseases through in situ production of therapeutic agents. When this treatment strategy is applied in cancer therapy, it can efficiently produce highly toxic anticancer drugs in situ from low‐toxic prodrugs or some biomolecules in tumor tissues, which can maximize the therapeutic efficacy with a significantly low systemic toxicity. An ideal therapeutic nanoreactor can provide the reaction space, protect the loaded fragile catalysts, target the desired pathological site, and be selectively activated. In this minireview, we highlight the recent advances concerning the applications of therapeutic nanoreactors as in vivo nanoplatforms particularly in cancer therapy. Herein, the therapeutic nanoreactors are discussed on the basis of treatment strategies and various nanoparticles. Specifically, the treatment strategies of nanoreactors including single enzyme, single enzyme with chemodrugs, and multienzymes, as well as varying types of engineered nanoparticle‐loaded active catalysts, primarily including liposomes, polymersomes, polymeric micelles, inorganic nanoparticles, and metal–organic framework (MOF) architectures, are documented and briefly discussed. Finally, we elucidate the current challenges to be addressed toward further development and translation into clinical applications of these therapeutic nanoreactors in cancer therapy. Small reactors for big medicine: This minireview summarizes the recent advances concerning the applications of therapeutic nanoreactors as in vivo nanoplatforms particularly for cancer therapy according to varying treatment strategies and types of nanoparticles. [ABSTRACT FROM AUTHOR]

Abstract: We describe elementary concepts, up‐to‐date developments, and perspectives of the emerging field of nanoparticle enzyme mimics (so‐called “nanozymes”) at the interface of chemistry, biology, materials, and nanotechnology. The design and synthesis of functional enzyme mimics is a long‐standing goal of biomimetic chemistry. Metal complexes, polymers and engineered biomolecules capturing the structure of natural enzymes or their active centers have been made to achieve high rates and enhanced selectivities. Still, the design of new “artificial enzymes” that are not related to proteins but with capacity of production and stability at industrial level, remains a goal. Inorganic nanoparticles bear this potential. Although it seems counterintuitive to compare nanoparticles and natural enzymes because they appear very different they share many common features: nano‐size, irregular shape, and rich surface chemistry. These features enable nanomaterials to mimic reactions of natural enzymes. Representative examples with biomedical and environmental applications are given. [ABSTRACT FROM AUTHOR]

Abstract: The elucidation of the mechanism by which the reduction of coordinatively saturated PtIV prodrugs occurs, leading to the release of the two axial ligands, is of foremost importance, being the key step for the activation of these anticancer compounds, and addressing their synthetic strategies. A systematic DFT computational analysis of the reduction process by small biomolecules, which is supposed to occur by inner‐ or outer‐sphere electron‐transfer mechanisms, has been undertaken using the recently synthesised Asplatin PtIV complex, c,c,t‐[PtCl2(NH3)2(OH)(aspirin)], as model system and l‐ascorbic acid as reducing agent. Further calculations have been carried out on Asplatin analogues that should be obtained replacing the OH− ligand with Cl− and Br−. The most accredited inner‐sphere mechanistic suggestions have been explored and a recently proposed computational methodology has been applied to estimate the corresponding standard redox potentials, which cannot be directly obtained from voltammetric experiments due to the irreversibility of the platinum(IV)‐to‐platinum(II) reduction process. [ABSTRACT FROM AUTHOR]

Abstract: Dynamic regulation of the interactions between specific molecules on functional surfaces and biomolecules, for example, proteins or cells, is critical for biosensor and biomedical devices. Herein, we present a spiropyran (SP)‐based light‐responsive surface coating, hPG (hyperbranched polyglycerol)‐SP, to control the adsorption of proteins and adhesion of cells. In the normal state, the SP groups on the coating surface were in hydrophobic ring‐closed form, which promotes the nonspecific protein adsorption and cell adhesion. Under UV irradiation, the grafted SP groups were dynamically isomerized into hydrophilic/zwitterionic merocyanine. Both hydrophilicity and zwitterions support the formation of a hydrated layer and hence the resulting hPG‐MC coatings highly resist protein adsorption and cell adhesion. Moreover, the presented hPG also provided a robust bioinert background to suppress the nonspecific protein adsorption and cells adhesion. Therefore, this functionalized coating exhibited a good photoregulated antifouling behavior. Moreover, the detachment of adsorbed proteins and adhered cells from the coating surface was also realized. [ABSTRACT FROM AUTHOR]

Abstract: Infrared multiphoton dissociation (IRMPD) spectroscopy is commonly used to determine the structure of isolated, mass‐selected ions in the gas phase. This method has been widely used since it became available at free‐electron laser (FEL) user facilities. Thus, in this Minireview, we examine the use of IRMPD/FEL spectroscopy for investigating ions derived from small molecules, metal complexes, organometallic compounds and biorelevant ions. Furthermore, we outline new applications of IRMPD spectroscopy to study biomolecules. [ABSTRACT FROM AUTHOR]

Peptidomimetics, non-natural mimicries of bioactive peptides, comprise an important class of drug molecules. The essence of the peptidomimetic design is to mimic the key conformation assumed by the bioactive peptides upon binding to their targets. Regulation of the conformation of peptidomimetics is important not only to enhance target binding affinity and selectivity, but also to confer cell-membrane permeability for targeting protein-protein interactions in cells. The rational design of peptidomimetics with suitable three-dimensional structures is challenging, however, due to the inherent flexibility of peptides and their dynamic conformational changes upon binding to the target biomolecules. In this Minireview, a three-dimensional structural diversity-oriented strategy based on the characteristic structural features of cyclopropane to address this challenging issue in peptidomimetic chemistry is described. [ABSTRACT FROM AUTHOR]

The incorporation of fluorinated moieties into organic structures is a particularly powerful approach for generating compounds with useful biological applications in industry, pharmacology, and agriculture. Here, the recently developed reagent-CF2HCHN2-selectively esterifies carboxyl groups on organic molecules in the presence of other polar functional groups. The reaction is remarkably simple, proceeding at room temperature in chloroform without addition of a catalyst. The procedure allows 'last-step' incorporation of a fluorinated ester moiety into organic structures, including bioorganic molecules such as peptides and proteins. The fluorinated ester can subsequently function as a 19F-probe in biomolecules, thereby enabling molecular size determination by diffusion 19F NMR experiments. [ABSTRACT FROM AUTHOR]

Three different mesoporous silica nano-sized materials (SC1, SC2, and SC3), loaded with [Ru(bipy)3]2+ dye (bipy=bipyridine) and functionalized on the external surface with three macrocyclic copper(II) complexes (C1, C2, and C3), were synthesized and characterized. When SC1, SC2, and SC3 were suspended in water, the entrapped [Ru(bipy)3]2+ dye was free to diffuse from the inner pores to the solution. However, addition of anions induced certain degrees of pore blockage, with subsequent dye release inhibition. Small monovalent and divalent anions were unable to induce complete pore blockage, whereas bulky and highly charged anions induced marked reductions in [Ru(bipy)3]2+ delivery. The best [Ru(bipy)3]2+ delivery inhibitors were ATP and hexametaphosphate anions. Inhibition was ascribed to the interaction of the anions with the grafted CuII complexes on the surface of the SC1, SC2, and SC3 supports. The hexametaphosphate anion was selected to prepare two capped materials (SC1-mPh and SC3-mPh). Studies of the [Ru(bipy)3]2+ dye release from solids SC1-mPh and SC3-mPh alone and in the presence of a collection of selected anions (HS-, F-, Br-, Cl-, I-, CN-, HPO42-, AcO-, citrate, NO32-, HCO3-, SO42-, and S2O82-), amino acids (alanine and histidine), thiol-containing biomolecules (cysteine, methylcysteine, homocysteine, and glutathione (GSH)), and oxidants (H2O2) were performed. None of the chemicals tested, except hydrogen sulphide, was able to induce remarkable cargo delivery in both solids. The observed dye release was ascribed to a demetalation reaction of the C1 and C3 complexes induced by the hydrogen sulphide anion. [ABSTRACT FROM AUTHOR]

Stimuli-responsive materials are of immense importance because of their ability to undergo alteration of their properties in response to their environment. The properties of such materials can be tuned by subtle adjustments in temperature, pH, light, and so forth. Among such smart materials, multi-stimuli-responsive polymeric materials are of pronounced significance as they offer a wide range of applications and their properties can be tuned through several mechanisms. Here, we aim to highlight some recent studies showcasing the multi-stimuli-responsive character of these polymers, which are still relatively little known compared to their single-stimuli-responsive counterpart. [ABSTRACT FROM AUTHOR]

Cells respond to alterations in their membrane structure by activating hydrolytic enzymes. Thus, polyunsaturated fatty acids (PUFAs) are liberated. Free PUFAs react with molecular oxygen to give lipid hydroperoxide molecules (LOOHs). In case of severe cell injury, this physiological reaction switches to the generation of lipid peroxide radicals (LOO.). These radicals can attack nearly all biomolecules such as lipids, carbohydrates, proteins, nucleic acids and enzymes, impairing their biological functions. Identical cell responses are triggered by manipulation of food, for example, heating/grilling and particularly homogenization, representing cell injury. Cholesterol as well as diets rich in saturated fat have been postulated to accelerate the risk of atherosclerosis while food rich in unsaturated fatty acids has been claimed to lower this risk. However, the fact is that LOO. radicals generated from PUFAs can oxidize cholesterol to toxic cholesterol oxides, simulating a reduction in cholesterol level. In this review it is shown how active LOO. radicals interact with biomolecules at a speed transcending usual molecule-molecule reactions by several orders of magnitude. Here, it is explained how functional groups are fundamentally transformed by an attack of LOO. with an obliteration of essential biomolecules leading to pathological conditions. A serious reconsideration of the health and diet guidelines is required. [ABSTRACT FROM AUTHOR]