Paclitaxel Overload Supramolecular Oxidative Stress Nanoamplifier with a CDK12 Inhibitor for Enhanced Cancer Therapy.

Combination therapy has emerged as a promising approach for treating tumors, although there is room for improvement. This study introduced a novel strategy that combined the enhancement of apoptosis, ferroptosis, and DNA damage to improve therapeutic outcomes for prostate cancer. Specifically, we have developed a supramolecular oxidative stress nanoamplifier, which was comprised of ß-cyclodextrin, paclitaxel, and ferrocene-poly(ethylene glycol). Paclitaxel within the system disrupted microtubule dynamics, inducing G2/M phase arrest and apoptosis. Concurrently, ferrocene utilized hydrogen peroxide to generate toxic hydroxyl radicals in cells through the Fenton reaction, triggering a cascade of reactive oxygen species expansion, reduction of glutathione levels, lipid peroxidation, and ferroptosis. The increased number of hydroxyl radicals and the inhibitory effect of THZ531 on DNA repair mechanisms exacerbated DNA damage within tumor cells. As expected, the supramolecular nanoparticles demonstrated excellent drug delivery ability to tumor cells or tissues, exhibited favorable biological safety in vivo, and enhanced the killing effect on prostate cancer.

Electroactive polymer tag modified nanosensors for enhanced intracellular ATP detection.

ATP plays a crucial role in cell energy supply, so the quantification of intracellular ATP levels is particularly important for understanding many physio-pathological processes. The intracellular quantification of this non-electroactive molecule can be realized using aptamer-modified nanoelectrodes, but is hindered by the limited quantity of modification and electroactive tags on the nanosized electrodes. Herein, we developed a simple but effective electrochemical signal amplification strategy for intracellular ATP detection, which replaces the regular ATP aptamer-linked ferrocene monomer with a polymer, thus greatly magnifying the amounts of electrochemical reporters linked to one chain of the aptamer and enhancing the signals. This ferrocene polymer-ATP aptamer was further immobilized onto Au nanowire electrodes (SiC@C@Au NWEs) to achieve accurate quantification of intracellular ATP in single cells, presenting high electrochemical signal output and high specificity. This work not only provides a powerful tool for quantifying intracellular ATP but also offers a simple and versatile strategy for electrochemical signal amplification in the detection of broader non-electroactive molecules involved in different kinds of intracellular physiological processes.

Design and Syntheses of New Antibiotics Inspired by Nature's Quest for Iron in an Oxidative Climate.

This Account describes fundamental chemistry that promoted the discovery of new antibiotics. Specifically, the NH acidity of simple hydroxamic acid derivatives facilitated the syntheses of novel ß-lactams (oxamazins and monobactams), siderophore mimics that limit bacterial iron uptake and bacterially targeted sideromycins (siderophore-antibiotic conjugates). The development of resistance to our current limited set of antibiotic scaffolds has created a dire medical situation. As recently stated, "if you weren't taking antibiotic resistance seriously before, now would be a good time to start." A project commissioned by the British government (https://amr-review.org/) has released estimates of the near-future global toll of antibiotic resistance that are jaw-dropping in their seriousness and scale: 10 million deaths per year and at least $100 trillion in sacrificed gross national product. The 2020 COVID pandemic confirmed that infectious disease problems are no longer localized but worldwide. Many classical antibiotics, especially ß-lactams, previously provided economical cures, but the evolution of antibiotic destructive enzymes (i.e., ß-lactamases), efflux pumps, and bacterial cell wall permeability barriers has made many types of bacteria, especially Gram-negative strains, resistant. Still, and in contrast to other therapies, the public expectation is that any new antibiotic must be inexpensive. This creates market limitations that have caused most major pharmaceutical companies to abandon antibiotic research. Much needs to be done to address this significant problem.The critical need for bacteria to sequester essential iron provides an Achilles' heel for new antibiotic development. Although ferric iron is extremely insoluble, bacteria need micromolar intracellular concentrations for growth and virulence. To this end, they biosynthesize siderophores (Gr. iron bearer) and excrete them into their environment, where they bind iron with high affinity. The iron complexes are recognized by specific outer-membrane transporters, and once actively internalized, the iron is released for essential processes. To conserve biosynthetic energy, some bacteria recognize and utilize siderophores made by competing strains. As a counter-revolution in the never-ending fight for survival, bacteria have also evolved sideromycins, which are siderophores conjugated to warheads that are lethal to rogue bacteria. While none are now used therapeutically, natural sideromycins called albomycins have been used clinically, and others have been shown to be well tolerated and active in animal infection models. Herein we describe practical methods to synthesize new antibiotics and artificial sideromycins with the generalized structure shown above (siderophore-linker drug). Utilizing the molecular-recognition-based siderophore/sideromycin bacterial assimilation processes, it is possible to design both broad spectrum and exquisitely narrow spectrum (targeted) sideromycins and even repurpose older or more classical antibiotics. Relevant microbiological assays, in vivo animal infection studies, and the recent FDA approval of cefiderocol demonstrate their effectiveness.

Spectrophotometric Determination of Trace Amount of Total FeII/FeIII and Live Cell Imaging of a Carboxylato Zn(II) Coordination Polymer.

The coordination polymer, (Zn(II)-CP, 1), {[Zn(2,6-NDC)(4-Cltpy)](H2O)4} (1) (2,6-H2NDC = 2,6-naphthalene dicarboxylic acid and 4-Cltpy = 4'-chloro-[2,2';6',2″]terpyridine) is structurally characterized by single crystal X-ray diffraction measurement and other physicochemical studies (PXRD, FTIR, thermal analysis, microanalytical data). 4-Cltpy acts as end-capping ligand, and NDC2- is a carboxylato bridging motif to constitute ZnN3O2 distorted trigonal bipyramid core that propagates to construct 1D chain. The coordination polymer, 1, detects total iron (Fe3+ and Fe2+) in aqueous solution by visual color change, colorless to pink. Absorption spectrophotometric technique in aqueous medium measures the limit of detection (LOD) 0.11 µM (Fe2+) and 0.15 µM (Fe3+), and binding constants (Kd) are 6.7 × 104 M-1 (Fe3+) and 3.33 × 104 M-1 (Fe2+). Biocompatibility of 1 is examined in live cells, and intracellular Fe2+ and Fe3+ are detected in MDA-MB 231 cells. Zn(II) substitution is assumed upon addition of FeIII/FeII solution to the suspension of the coordination polymer, 1, in water-acetonitrile (41:1) (LZnII + FeIII/II → LFeIII + ZnII, where L is defined as coordinated ligands), which is accompanied by changing from colorless to pink at room temperature. The color of the mixture may be assumed to the charge transfer transition from carboxylate-O to Cltpy via Fe(II/III) bridging center (carboxylate-O-Fe-CltPy). The product isolated from the reaction is finally characterized as Fe(III)@1-CP. It is presumed that product Fe(II)@1-CP may undergo fast aerial oxidation to transform Fe(III)@1-CP. The FeIII exchanged framework (Fe(III)@1-CP) has been characterized by PXRD, IR, TGA and energy dispersive X-ray analysis (EDX)-SEM. The MTT assay calculates the cell viability (%), and the tolerance limit is 100 µM to total Fe2+ and Fe3+.

Selenide [Se(-II)] Immobilization in Anoxic, Fe(II)-Rich Environments: Coprecipitation and Behavior during Phase Transformations.

The radionuclide selenium-79 (Se-79) is predicted to be a key contributor to the long-term radiologic hazards associated with geological high-level waste (HLW) repositories; hence its release is of pertinent concern in the safety assessment of repositories. However, interactions of reduced Se species with aqueous Fe(II) species and solid phases arising from the corrosion of a steel overpack could play a role in mitigating its migration to the surrounding environment. In this study, we examined the immobilization mechanisms of Se(-II) during its interaction with aqueous Fe(II) and freshly precipitated Fe(OH)2 at circumneutral and alkaline conditions, respectively, its response to changes in pH, and its behavior during aging at 90 °C. Using microscopic and spectroscopic techniques, we observed ß-FeSe precipitation, regardless of whether Se(-II) reacts with aqueous species or solid phases, and that modifying the pH following initial immobilization did not remobilize Se(-II). These observations indicate that Se(-II) migration beyond the overpack can be effectively and rapidly retarded via interactions with Fe(II) species arising from overpack corrosion. Thermodynamic calculations, however, showed that iron selenides became metastable at alkaline conditions and will dissolve in the long term. Aging experiments at 90 °C showed that Se(-II) can be completely retained via the crystallization of ferroselite at circumneutral conditions, while it will be largely remobilized at alkaline conditions. Our results show that Se(-II) mobility can be significantly influenced by its interactions with the corrosion products of the steel overpack and that these behaviors will have to be considered in repository safety assessments.

Production of Hydroxyl Radicals from Oxygenation of Simulated Acid Mine Drainage in Presence of Extracellular Polymers Substances.

The reaction mechanisms Fe(II) abiotic oxidation produce ·OH by CaCO3-induced in acid mine drainage (AMD) are well-documented, but little is known about the influence of extracellular polymeric substances (EPS) secreted by microorganisms on Fe(II) oxidation in AMD. In this study, ·OH production was experimently measured from oxygenation of simulated AMD in the presence of EPS. The cumulative ·OH increased from 56.75 to 158.70 µM within 24 h at pH 3 with the increase in EPS concentration from 0 to 12 mg/L. An appropriate pH (about 6) and EPS (6 mg/L) concentration were required for the moderate rate of Fe(II) oxidation. Besides, the yield of ·OH increased remarkably with the addition of Fe3+. In the presence of EPS, ·OH production is attributed mainly the complexation of Fe(II) with EPS, of which is rich of carboxyl and hydroxyl groups. The findings provide fundamental supplement of ·OH production from Fe(II) oxidation by microorganisms in natural AMD.

Dendritic Micelles with Controlled Branching and Sensor Applications.

Although micelles derived from the solution self-assembly of amphiphilic molecules and polymers have been prepared with a wide variety of shapes, examples with well-defined branched structures have remained elusive. We describe a divergent, directed self-assembly approach to low dispersity dendritic micelles with a high degree of structural perfection and tailorable branch numbers and generations. We use block copolymer amphiphiles as precursors and a crystallization-driven seeded growth approach whereby the termini of fiber-like micelles function as branching sites. Different dendrimeric generations are accessible by adjusting the ratio of added unimers to pre-existing seed micelles where the branch positions are determined by the reduced coronal chain grafting density on the surface of the micelle crystalline core. We demonstrate the spatially defined decoration of the assemblies with emissive nanoparticles and utility of the resulting hybrids as fluorescent sensors for anions where the dendritic architecture enables ultrahigh sensitivity.

Designing highly stable ferrous selenide-black phosphorus nanosheets heteronanostructure via P-Se bond for MRI-guided photothermal therapy.

BACKGROUND: The design of stable and biocompatible black phosphorus-based theranostic agents with high photothermal conversion efficiency and clear mechanism to realize MRI-guided precision photothermal therapy (PTT) is imminent. RESULTS: Herein, black phosphorus nanosheets (BPs) covalently with mono-dispersed and superparamagnetic ferrous selenide (FeSe2) to construct heteronanostructure nanoparticles modified with methoxy poly (Ethylene Glycol) (mPEG-NH2) to obtain good water solubility for MRI-guided photothermal tumor therapy is successfully designed. The mechanism reveals that the enhanced photothermal conversion achieved by BPs-FeSe2-PEG heteronanostructure is attributed to the effective separation of photoinduced carriers. Besides, through the formation of the P-Se bond, the oxidation degree of FeSe2 is weakened. The lone pair electrons on the surface of BPs are occupied, which reduces the exposure of lone pair electrons in air, leading to excellent stability of BPs-FeSe2-PEG. Furthermore, the BPs-FeSe2-PEG heteronanostructure could realize enhanced T2-weighted imaging due to the aggregation of FeSe2 on BPs and the formation of hydrogen bonds, thus providing accurate PTT guidance and generating hyperthermia to inhabit tumor growth under NIR laser with negligible toxicity in vivo. CONCLUSIONS: Collectively, this work offers an opportunity for fabricating BPs-based heteronanostructure nanomaterials that could simultaneously enhance photothermal conversion efficiency and photostability to realize MRI-guided cancer therapy.

Fe(II) Spin Crossover/Polymer Hybrid Materials: Investigation of the SCO Behavior via Temperature-Dependent Raman Spectroscopy, Physicochemical Characterization and Migration Release Study.

Polymeric composites constitute an appealing class of materials with applications in various fields. Spin crossover (SCO) coordination complexes are switchable materials with potential use in data storage and sensors. Their incorporation into polymers can be considered an effective method for their wider practical application. In this study, Fe(II) SCO/polylactic acid hybrid polymeric composites have been prepared by film casting. The mononuclear coordination complex [Fe{N(CN)2}2(abpt)2] was incorporated into polylactic acid. The morphological, structural and thermoanalytical characterization of the composite films were performed via scanning electron microscopy (SEM), attenuated total reflectance (ATR/FTIR), Raman spectroscopy and differential scanning calorimetry (DSC). In addition, the migration release study (MRS) of the SCO compound from the polymeric matrix into the food simulant 50% v/v water/ethanol solution was also examined via UV/Vis absorption. Of particular interest was the investigation of the SCO behavior of the coordination complex after its incorporation into the polymer matrix; it was accomplished by temperature-dependent micro-Raman spectroscopy. The described attempt could be considered a preparatory step toward the development of SCO-based temperature sensors integrated into food packaging materials.

Ferrocene Functionalized Upconversion Nanoparticle Nanosystem with Efficient Near-Infrared-Light-Promoted Fenton-Like Reaction for Tumor Growth Suppression.

By taking advantage of the efficient Förster resonance energy transfer (FRET) between near-infrared (NIR)-responsive lanthanide-doped upconversion nanoparticles (UCNPs) and Fenton reagent ferrocenyl compounds (Fc), a series of Fc-UCNPs was designed by functionalizing NaYF4:Yb,Tm nanoparticles with Fc1-Fc5 via surface-coordination chemistry. Fc-UCNP-Lipo nanosystems were then constructed by encapsulating Fc-UCNP inside liposomes for efficient delivery. Fc-UCNP can effectively release ·OH via a NIR-promoted Fenton-like reaction. In vitro and in vivo studies of Fc1-UCNP-Lipo confirmed the preferential accumulation in a tumor site followed by an enhanced uptake of cancer cells. After cellular internalization, the released Fc1-UCNP can effectively promote ·OH generation for tumor growth suppression. Such a Fc1-UCNP-Lipo nanosystem exhibits advantages such as easy fabrication, low drug dosage, and no ferrous ion release.

Sensor based on redox conjugated poly(para-phenylene) for the simultaneous detection of dopamine, ascorbic acid, and uric acid in human serum sample.

An electrochemical sensor for the individual and the simultaneous detection of dopamine (DA), ascorbic acid (AA), and uric acid (UA) based on redox conjugated "poly(para-phenylene)" (Fc-ac-PPP) bearing ferrocene and carboxylic acid in lateral position has been developed. The electrochemical characterization of the sensor has been studied with cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CA). We highlighted that the catalytic activity of the Fc-ac-PPP polymer provided by its redox electrochemical properties and chemical structure allows the electrochemical detection of DA, AA, and UA. We demonstrated that the sensor provides high sensitivity and selective signal in the coexistence of DA, AA, and UA within a short time. Low detection limits and wide linear ranges of detection have been demonstrated respectively for DA 3 × 10-10 M (1 nM-10 µM), AA 1.6 × 10-8 M (0.1 µM-1 mM), and UA 1 × 10-8 M (0.1 µM-1 mM). In addition, the sensor has been successfully applied to determine DA in urine and human serum samples even in the presence of high concentrations of AA and UA. This sensor could be a powerful device for the detection of other electroactive compounds thanks to its high catalytic properties and chemical structure. Graphical abstract.

Precise Synthesis of Alternate Fe(II)/Os(II)-Based Bimetallic Metallo-Supramolecular Polymer.

A novel terpyridine-based bimetallic metallo-supramolecular polymer (polyFeOs) containing alternately complexed Fe(II) and Os(II) ions is synthesized. For precise synthesis of the polymer, a new three-step synthetic pathway is developed to obtain a high yield (%) of product in each step. The first step is the synthesis of dibromo terpyridine-Os(II) complex in 87% yield, the second step is the synthesis of bisterpyridine ligand containing Os(II) (OsL1) in 74% yield, and the last step is the synthesis of polyFeOs in 90% yield. The polyFeOs exhibits high thermal stability with two degradation temperatures at around 390 and 690 °C, which indicate thermal evaporation of the counter anions (Cl- and BF4 - ) and degradation of the coordination bonds, respectively. The combination of two different metal ions in polyFeOs results in an enlarged optical window (λ = 315-675 nm) and two highly stable reversible redox states, which can be of huge interest for potential optical, electro-optical, and electrochemical applications.

Ferrous and Ferric Ion-Facilitated Dilute Acid Pretreatment of Lignocellulosic Biomass under Anaerobic or Aerobic Conditions: Observations of Fe Valence Interchange and the Role of Fenton Reaction.

Ferrous ion co-catalyst enhancement of dilute-acid (DA) pretreatment of biomass is a promising technology for increasing the release of sugars from recalcitrant lignocellulosic biomass. However, due to the reductive status of ferrous ion and its susceptibility to oxidation with exposure to atmosphere, its effective application presumably requires anaerobic aqueous conditions created by nitrogen gas-purging, which adds extra costs. The objective of this study was to assess the effectiveness of oxidative iron ion, (i.e., ferric ion) as a co-catalyst in DA pretreatment of biomass, using an anaerobic chamber to strictly control exposure to oxygen during setup and post-pretreatment analyses. Remarkably, the ferric ions were found to be as efficient as ferrous ions in enhancing sugar release during DA pretreatment of biomass, which may be attributed to the observation that a major portion of the initial ferric ions were converted to ferrous during pretreatment. Furthermore, the detection of hydrogen peroxide in the liquors after DA/Fe ion pretreatment suggests that Fenton reaction chemistry was likely involved in DA/Fe ion pretreatments of biomass, contributing to the observed ferric and ferrous interchanges during pretreatment. These results help define the extent and specification requirements for applying iron ions as co-catalysts in DA pretreatments of biomass.

3D Micro/Nanopatterning of a Vinylferrocene Copolymer.

In nanoimprint lithography (NIL), a pattern is created by mechanical deformation of an imprint resist via embossing with a stamp, where the adhesion behavior during the filling of the imprint stamp and its subsequent detachment may impose some practical challenges. Here we explored thermal and reverse NIL patterning of polyvinylferrocene and vinylferrocene-methyl methacrylate copolymers to prepare complex non-spherical objects and patterns. While neat polyvinylferrocene was found to be unsuitable for NIL, freshly-prepared vinylferrocene-methyl methacrylate copolymers, for which identity and purity were established, have been structured into 3D-micro/nano-patterns using NIL. The cross-, square-, and circle-shaped columnar structures form a 3 × 3 mm arrangement with periodicity of 3 µm, 1 µm, 542 nm, and 506 nm. According to our findings, vinylferrocene-methyl methacrylate copolymers can be imprinted without further additives in NIL processes, which opens the way for redox-responsive 3D-nano/micro-objects and patterns via NIL to be explored in the future.

Synthesis of an Alternated Heterobimetallic Supramolecular Polymer Based on Ru(II) and Fe(II).

A heterobimetallic supramolecular polymer (polyRuFe) with alternately complexed Ru(II) and Fe(II) is prepared following a stepwise synthetic route through harnessing first the strongly binding metal ion Ru(II) and then the weakly binding metal ion Fe(II). A high yield of product is achieved in each step. The heterometal ions are incorporated into the polymer chain in identical coordination environments formed by two 2,2':6',2″-terpyridine moieties. Characterization is accomplished by NMR spectroscopy, MALDI-TOF mass spectrometry, UV-Vis spectroscopy, and cyclic voltammetry. PolyRuFe shows a wide optical window (λ = 311-577 nm) and a broad distinct reversible redox nature of two types, originated from the coupling of the two heterometallic segments into the polymer chain. Such characteristics of polyRuFe suggest its potential for various electrochemical and electro-optical applications.

Nanogel Multienzyme Mimics Synthesized by Biocatalytic ATRP and Metal Coordination for Bioresponsive Fluorescence Imaging.

The design of enzyme mimics from stable and nonprotein systems is especially attractive for applications in highly specific cancer diagnosis and treatment, and it has become an emerging field in recent years. Herein, metal crosslinked polymeric nanogels (MPGs) were prepared using FeII ion coordinated biocompatible acryloyl-lysine polymer brushes obtained from an enzyme-catalyzed atomic transfer radical polymerization (ATRPase) method. The monoatomic and highly dispersed Fe ions in the MPGs serve as efficient crosslinkers of the gel network, and also as active centers of multienzyme mimics of superoxide dismutase (SOD) and peroxidase (POD). The catalytic activities were compared to those of conventional Fe-based nanozymes. Studies on both cells and animals verify that efficient reactive oxygen species (ROS) responsive biofluorescence imaging can be successfully realized using the MPGs.

Synergistic Amplification of Oxidative Stress-Mediated Antitumor Activity via Liposomal Dichloroacetic Acid and MOF-Fe2.

Cancer cells are susceptible to oxidative stress; therefore, selective elevation of intracellular reactive oxygen species (ROS) is considered as an effective antitumor treatment. Here, a liposomal formulation of dichloroacetic acid (DCA) and metal-organic framework (MOF)-Fe2+ (MD@Lip) has been developed, which can efficiently stimulate ROS-mediated cancer cell apoptosis in vitro and in vivo. MD@Lip can not only improve aqueous solubility of octahedral MOF-Fe2+ , but also generate an acidic microenvironment to activate a MOF-Fe2+ -based Fenton reaction. Importantly, MD@Lip promotes DCA-mediated mitochondrial aerobic oxidation to increase intracellular hydrogen peroxide (H2 O2 ), which can be consequently converted to highly cytotoxic hydroxyl radicals (•OH) via MOF-Fe2+ , leading to amplification of cancer cell apoptosis. Particularly, MD@Lip can selectively accumulate in tumors, and efficiently inhibit tumor growth with minimal systemic adverse effects. Therefore, liposome-based combination therapy of DCA and MOF-Fe2+ provides a promising oxidative stress-associated antitumor strategy for the management of malignant tumors.

Redox-Triggered Disassembly of Nanosized Liposomes Containing Ferrocene-Appended Amphiphiles.

We report a redox-responsive liposomal system capable of oxidatively triggered disassembly. We describe the synthesis, electrochemical characterization, and incorporation into vesicles of an alternative redox lipid with significantly improved synthetic efficiency and scalability compared to a ferrocene-appended phospholipid previously employed by our group in giant vesicles. The redox-triggered disassembly of both redox lipids is examined in nanosized liposomes as well as the influence of cholesterol mole fraction on liposome disassembly and suitability of various chemical oxidants for  in vitro disassembly experiments. Electronic structure density functional theory calculations of membrane-embedded ferrocenes are provided to characterize the role of charge redistribution in the initial stages of the disassembly process.

An electrochemical aptasensor based on eATRP amplification for the detection of bisphenol A.

Herein, a novel aptasensor was constructed for ultrasensitive detection of bisphenol A (BPA). In this method, an electrochemically mediated atom transfer radical polymerization (eATRP) signal amplification strategy was applied to BPA detection for the first time. The 5'-end modified sulfhydryl group and the 3'-end modified azide group hairpin DNA were immobilized on a gold electrode through an Au-S bond. The double-stranded DNA was formed by the hybridization of an aptamer and a single-stranded DNA partially paired with the hairpin DNA. In the presence of BPA, the aptamer combined with BPA and the single-stranded DNA was released to open the hairpin structure, making the azide groups at the 3' end exposed. Subsequently the initiator of eATRP was introduced into hairpin DNA through click chemistry reaction and eATRP was conducted for the polymerization of the electroactive probe ferrocene methyl methacrylate (FMMA). As a result, the ultrasensitive detection of BPA was realized, and the detection limit of this aptasensor was as low as 59 aM and a good selectivity was obtained in the presence of 100-fold structural analogs. The application of this aptasensor was evaluated by detecting BPA in pure water samples, and recoveries were in the range of 95.23-98.40%, holding promising applications in biological analysis.

Dually Cross-Linked Supramolecular Hydrogel as Surface Plasmon Resonance Sensor for Small Molecule Detection.

Dually cross-linked supramolecular hydrogels (DCSH) are designed to show responsive properties while maintaining the gel structure by introducing two different kinds of cross-links. This is realized by utilizing a photo-cross-linker for permanent cross-linking and ß-cyclodextrin (ß-CD) and ferrocene (Fc) as host-guest recognition pair. The DCSH shows increased swelling in the presence of the small target molecule adamantane amine (Ada). Ada can break the non-covalent bonding between ß-CD and Fc through competitive molecular guest interaction with ß-CD. By using a combination of surface plasmon resonance and optical waveguide spectroscopy, it is possible to use this behavior to construct a reversible sensor for specific small molecule detection.