Thermo Response Research Articles

Wound Microenvironment Self-Adjusting Hydrogels with Thermo-Sensitivity for Promoting Diabetic Wound Healing.

The hard-healing chronic wounds of diabetics are still one of the most intractable problems in clinical skin injury repair. Wound microenvironments directly affect wound healing speed, but conventional dressings exhibit limited efficacy in regulating the wound microenvironment and facilitating healing. To address this serious issue, we designed a thermo-sensitive drug-controlled hydrogel with wound self-adjusting effects, consisting of a sodium alginate (SA), Antheraeapernyi silk gland protein (ASGP) and poly(N-isopropylacrylamide) (PNIPAM) for a self-adjusting microenvironment, resulting in an intelligent releasing drug which promotes skin regeneration. PNIPAM has a benign temperature-sensitive effect. The contraction, drugs and water molecules expulsion of hydrogel were generated upon surpassing lower critical solution temperatures, which made the hydrogel system have smart drug release properties. The addition of ASGP further improves the biocompatibility and endows the thermo-sensitive drug-controlled hydrogel with adhesion. Additionally, in vitro assays demonstrate that the thermo-sensitive drug-controlled hydrogels have good biocompatibility, including the ability to promote the adhesion and proliferation of human skin fibroblast cells. This work proposes an approach for smart drug-controlled hydrogels with a thermo response to promote wound healing by self-adjusting the wound microenvironment.

Thermo-pH-Salt Environmental Terpolymers Influenced by 2-((Dimethylamino)methyl)-4-methylphenyl Acrylate: A Comparative Study for Tuning Phase Separation Temperature.

This study offers a comparison between three different types of thermoresponsive (TR) and thermo-pH-salt (TPR) multiresponsive polymers including homopoly(N-isopropylacrylamide) (PNIPAAm), copolymers with three different monomers, 2-hydroxyethyl methacrylate (HEMA), N,N-dimethylacrylamide (DMAAm), and styrene (S) at three different concentrations (5, 10, and 20 mol %), and a PNIPAAm terpolymer with 5, 10, and 20 mol % 2-((dimethylamino)methyl)-4-methylphenyl acrylate (DMAMCA) and 10 mol % HEMA, DMAAm, and S monomers. All polymers were chemically analyzed with 1H NMR and Fourier transform infrared spectroscopy (FT-IR) as well as gel permeation chromatography (GPC) for the molecular weights and dispersity and differential scanning calorimeter (DSC) for the glass transition temperatures. The cloud point, also known as the phase separation temperature (Cp), was determined for all polymers by a turbidity test using a UV-vis spectrophotometer; a micro-differential scanning calorimeter was used for measuring the cloud point in deionized water. The influence of a tertiary amine cationic group of DMAMCA changed the behavior of TR copolymers into TPR by shifting the cloud point of the TPR to higher values in acidic solutions (lower pH) and to lower values in alkaline solutions. The Cp was measured at different concentrations of Hofmeister kosmotropic and chaotropic anion salt solutions in a range of pH solutions for the terpolymers. It demonstrated the same behavior as mentioned in pH solutions besides the effect of salt ions. By measuring the Tc and Cp of these polymers, we can exploit various applications of stimuli-responsive materials for sensors and biomedical technology.

CuFeS2 Nanoparticles Functionalized with a Thermoresponsive Polymer for Photothermia and Externally Controlled Drug Delivery

CuFeS2 chalcopyrite nanoparticles (NPs) can generate heat under exposure to near-infrared laser irradiation. Here, we develop a protocol to decorate the surface of CuFeS2 NPs (13 nm) with a thermoresponsive (TR) polymer based on poly(ethylene glycol methacrylate) to combine heat-mediated drug delivery and photothermal heat damage. The resulting TR-CuFeS2 NPs feature a small hydrodynamic size (∼75 nm), along with high colloidal stability and a TR transition temperature of 41 °C in physiological conditions. Remarkably, TR-CuFeS2 NPs, when exposed to a laser beam (in the range of 0.5 and 1.5 W/cm2) at NP concentrations as low as 40-50 μg Cu/mL, exhibit a high heating performance with a rise in the solution temperature to hyperthermia therapeutic values (42-45 °C). Furthermore, TR-CuFeS2 NPs worked as nanocarriers, being able to load an appreciable amount of doxorubicin (90 μg DOXO/mg Cu), a chemotherapeutic agent whose release could then be triggered by exposing the NPs to a laser beam (through which a hyperthermia temperature above 42 °C could be reached). In an in vitro study performed on U87 human glioblastoma cells, bare TR-CuFeS2 NPs were proven to be nontoxic at a Cu concentration up to 40 μg/mL, while at the same low dose, the drug-loaded TR-CuFeS2-DOXO NPs displayed synergistic cytotoxic effects due to the combination of direct heat damage and DOXO chemotherapy, under photo-irradiation by a 808 nm laser (1.2 W/cm2). Finally, under a 808 nm laser, the TR-CuFeS2 NPs generated a tunable amount of reactive oxygen species depending on the applied power density and NP concentration.

Modifying the Properties of Microemulsion Droplets by Addition of Thermoresponsive BAB* Copolymers.

Oil-in-water (O/W) microemulsions (ME) typically feature a low viscosity and exhibit ordinary viscosity reduction as a function of temperature. However, for certain applications, avoiding or even reverting the temperature trend might be required. This can be conceived by adding thermoresponsive (TR) block copolymers that induce network formation as the temperature increases. Accordingly, various ME-polymer mixtures were studied for which three different block copolymer architectures of BAB*-, B2AB*-, and B(AB*)2-types were employed. Here, "B" represents a permanently hydrophobic, "A" a permanently hydrophilic, and "B*" a TR block. For the TR-block, three different poly(acrylamide)s, namely poly(N-n-propylacrylamide) (pNPAm), poly(N,N-diethylacrylamide) (pDEAm), and poly(N-isopropylacrylamide) (pNiPAm), were used, which all exhibit a lower critical solution temperature. For a well-selected ME concentration, these block copolymers lead to a viscosity enhancement with increasing temperature. At a polymer concentration of about 22 g L-1, the most pronounced enhancement was observed for the pNPAm-based systems with factors up to 3, 5, and 8 for BAB*, B2AB*, and B(AB*)2, respectively. This phenomenon is caused by the formation of a transitory network mediated by TR-blocks, as evidenced by the direct correlation between the attraction strength and the viscosity enhancement. For applications requiring a high hydrophobic payload, which is attained via ME droplets, this kind of tailored temperature-dependent viscosity control of surfactant systems should therefore be advantageous.

Swelling of Thermo-Responsive Gels in Aqueous Solutions of Salts: A Predictive Model.

The equilibrium degree of swelling of thermo-responsive (TR) gels is strongly affected by the presence of ions in an aqueous solution. This phenomenon plays an important role in (i) the synthesis of multi-stimuli-responsive gels for soft robotics, where extraordinary strength and toughness are reached by soaking of a gel in solutions of multivalent ions, and (ii) the preparation of hybrid gels with interpenetrating networks formed by covalently cross-linked synthetic chains and ionically cross-linked biopolymer chains. A model is developed for equilibrium swelling of a TR gel in aqueous solutions of salts at various temperatures T below and above the critical temperature at which collapse of the gel occurs. An advantage of the model is that it involves a a small (compared with conventional relations) number of material constants and allows the critical temperature to be determined explicitly. Its ability (i) to describe equilibrium swelling diagrams on poly(N-isopropylacrylamide) gels in aqueous solutions of mono- and multivalent salts and (ii) to predict the influence of volume fraction of salt on the critical temperature is confirmed by comparison of observations with results of numerical simulation.

Equilibrium Swelling of Thermo-Responsive Gels in Mixtures of Solvents

Thermo-responsive (TR) gels of the LCST (lower critical solution temperature) type swell in water at temperatures below their volume phase transition temperature Tc and collapse above the critical temperature. When water is partially replaced with an organic liquid, these materials demonstrate three different types of equilibrium solvent uptake diagrams at temperatures below, above, in the close vicinity of Tc. A model is developed for equilibrium swelling of TR gels in binary mixtures of solvents. It takes into account three types of phase transitions in TR gels driven by (i) aggregation of hydrophobic side groups into clusters from which solvent molecules are expelled, (ii) replacement of water with cosolvent molecules in cage-like structures surrounding these groups, and (iii) replacement of water with cosolvent as the main element of hydration shells around backbone chains. The model involves a relatively small number of material constants that are found by matching observations on covalently cross-linked poly(N-isopropylacrylamide) macroscopic gels and microgels. Good agreement is demonstrated between the experimental data and results of numerical analysis. Classification is provided of the phase transition points on equilibrium swelling diagrams.

Swelling of composite microgels with soft cores and thermo-responsive shells

This study deals with constitutive modeling and numerical simulation of equilibrium swelling of composite microgels with soft temperature-insensitive cores and thermo-responsive (TR) shells. Our analysis takes into account a pronounced increase in the elastic moduli of TR gels of the LCST (lower critical solution temperature) type driven by aggregation of hydrophobic segments into clusters above the volume phase transition temperature. Material parameters are found by fitting observations on poly(acrylamide) and poly(N-isopropylacrylamide) gels with various concentrations of cross-linkers. Good agreement is demonstrated between the experimental data and results of numerical analysis. The effects of mechanical properties of the core and the shell and geometry of composite microgels on distribution of water molecules are studied numerically. Several unexpected phenomena are discovered in simulation.

Modulation of the volume phase transition temperature for multi-stimuli-responsive copolymer hydrogels

Thermo-responsive (TR) hydrogels of the LCST (low critical solution temperature) type swell noticeably below their volume phase transition temperature Tc and collapse above Tc. Biomedical applications of these gels (in particular, for controlled delivery of nuclear acids and genes) require fine tuning of the critical temperature. Modulation of Tc is conventionally performed by copolymerization of TR monomers with monomers whose hydrophilicity is higher or lower than that of the main monomers. The most pronounced changes in Tc are observed when TR monomers are copolymerized with anionic or cationic monomers. Introduction of polyelectrolyte monomers into the polymer network induces a strong dependence of its properties on pH and ionic strength of an aqueous solution. A constitutive model is developed to describe the effects of pH and molar fraction of salt in a solution on the critical temperature of TR polyelectrolyte hydrogels. Adjustable parameters are found by fitting equilibrium swelling diagrams on copolymer gels with strongly and weakly dissociating cationic functional groups. The ability of the model to predict Tc is confirmed by comparison of experimental data with results of simulation.

Synergistic Stain Removal Achieved by Controlling the Fractions of Light and Thermo Responsive Components in the Dual-Responsive Copolymer Immobilized on Cotton Fabrics by Cross-Linker.

Enhanced synergistic stain removal is realized by tailoring the comonomer fractions of a light- and thermo-dual responsive copolymer, which is immobilized on cotton fabrics by a cross-linker. The copolymer poly(acrylamide azobenzene-co-ethylene glycol methacrylate-co-triethylene glycol methyl ether methacrylate), denoted P(AAAB1-co-EGMA2-co-MEO3MA17), is prepared by the ATRP polymerization method. The present molar ratio for these monomers is 1:2:17. Because of the existence of the light-responsive AAAB unit, the transition temperature of its aqueous solution under UV radiation is shifted to 39 °C, which is 2 °C higher than that in ambient conditions. This increase is caused by the trans-cis isomerization from the azobenzene groups, indicating an increased hydrophilicity of P(AAAB1-co-EGMA2-co-MEO3MA17) under UV radiation. After being immobilized onto cotton fabrics by a cross-linker, they are also dual-responsive. The equilibrium swelling ratio (ESR) of the cotton fabrics is further increased after UV radiation. Compared to our former investigation, the reduction of the AAAB molar fraction from 0.1 to 0.05 causes an increase of the ESR value by 10%. Moreover, the stain removal efficiency of the cotton fabrics immobilized with P(AAAB1-co-EGMA2-co-MEO3MA17) by cross-linker is also significantly improved under UV radiation. The hydrophilicity of the copolymer mainly from the MEO3MA units is crucial to the cleaning capability. Additionally lowering the attachment between stain and the copolymer coating on the cotton fabrics by trans-cis isomerization in those AAAB units also favors the cleaning. Hence, the stain removal is strongly improved by optimizing the fraction of light- versus thermo-responsive components in the copolymer, which can profoundly reduce the consumption of chemical detergents and energy during laundry.

Equilibrium Swelling of Biocompatible Thermo-Responsive Copolymer Gels.

Biomedical applications of thermo-responsive (TR) hydrogels require these materials to be biocompatible, non-cytotoxic, and non-immunogenic. Due to serious concerns regarding potential toxicity of poly(N-isopropylacrylamide) (PNIPAm), design of alternative homo- and copolymer gels with controllable swelling properties has recently become a hot topic. This study focuses on equilibrium swelling of five potential candidates to replace PNIPAm in biomedical and biotechnological applications: poly(N-vinylcaprolactam), poly(vinyl methyl ether), poly(-dimethyl amino ethyl methacrylate), and two families of poly(2-oxazoline)s, and poly(oligo(ethylene glycol) methacrylates). To evaluate their water uptake properties and to compare them with those of substituted acrylamide gels, a unified model is developed for equilibrium swelling of TR copolymer gels with various types of swelling diagrams. Depending on the strength of hydrophobic interactions (high, intermediate, and low), the (co)polymers under consideration are split into three groups that reveal different responses at and above the volume phase transition temperature.

The effects of pH and ionic strength on the volume phase transition temperature of thermo-responsive anionic copolymer gels

Applications of thermo-responsive (TR) gels in biomedicine and biotechnoligy require modulation of their volume phase transition temperature Tc in a rather wide interval. This is conventionally performed by incorporation of hydrophilic or hydrophobic monomers in the feed. The most pronounced growth of Tc occurs when TR monomers are copolymerized with anionic, cationic or ampholyte monomers.The effect of ionic monomers on the volume phase transition temperature of copolymer gels is traditionally analyzed in equilibrium swelling tests in distilled water. To evaluate how pH and ionic strength of aqueous solutions affect Tc, a constitutive model is developed. Adjustable parameters are found by fitting observations on poly(N-isopropylacrylamide-co-acrylic acid) and poly(N-isopropylacrylamide-co-itaconic acid) macro- and microgels below and above their critical temperature. The ability of the model to predict Tc is validated by comparison of experimental data with results of simulation. An analytical formula is derived that describes the influence of molar fraction of comonomers, pH and molar fraction of salt in aqueous solutions on the volume phase transition temperature of TR anionic gels.

Modulation of the volume phase transition temperature of thermo-responsive gels

Thermo-responsive (TR) gels swell substantially below their volume phase transition temperature Tc and shrink above this temperature. Applications of TR gels in controlled drug delivery and their use as biosensors and temperature-triggered soft actuators require fine tuning of Tc. As the critical temperature is independent of the preparation conditions and molar fractions of monomers and cross-linkers, it is modulated by incorporation of (neutral or ionic) monomers and polymer chains into pre-gel solutions for TR gels.A model is developed for the mechanical response and equilibrium swelling of TR gels. Analytical formulas are derived for the effect of molar fraction of comonomers on the volume phase transition temperature Tc in copolymer gels and gels with semi-interpenetrating networks. Adjustable parameters are found by fitting equilibrium swelling diagrams on poly(N,N-diethylacrylamide) gels. Good agreement is demonstrated between predictions of the model and experimental data.

Thermally Induced Switch of Coupling Reaction Using the Morphological Change of a Thermoresponsive Polymer on a Reactive Heteroarmed Nanoparticle.

Control of the cross-linking reaction is imperative when developing a sophisticated in situ forming hydrogel in the body. In this study, a heteroarmed thermoresponsive (TR) nanoparticle was designed to investigate the mechanism of controlling reactivity of the functional groups introduced into the nanoparticles. The coupling reaction was suppressed/proceeded by utilizing temperature-induced morphological changes of the TR polymer. The heteroarmed TR nanoparticle was prepared by the coassembly of amphiphilic block copolymers possessing both a TR segment and hydrophilic segment with reactive functional groups of succinimide. The longer TR chain on the nanoparticle covered the succinimide group and suppressed the reaction with the primary amine on the external nanoparticle. In contrast, the coupling reaction was promoted at a high temperature to create the chemical cross-linking structure between the nanoparticles because of the exposure of the succinimide group on the surface of the particle as a consequence of the morphological change of the TR polymer. In addition, the thermally controlled chemical reaction modulated initiation of the gelation using a highly concentrated nanoparticle solution. The heteroarmed TR nanoparticle offers great practical advantages for clinical uses, such as embolization agents, through precise control of the reaction.

PH and thermo responsive aliphatic tertiary amine chromophore hyperbranched poly(amino ether ester)s from oxa‐Michael addition polymerization

AbstractIn this research, we developed a novel and facile strategy to prepare aliphatic tertiary amine chromophore hyperbranched poly(amino ether ester)s with pH and thermo responsiveness via phosphazene base (t‐BuP2) catalyzed oxa‐Michael addition polymerization of triethanolamine with ethylene glycol diacrylate at room temperature. UV–vis and fluorescence analyses results showed that the tertiary amine at branching point for hyperbranched poly(amino ether ester)s is very important to retain strong blue fluorescence of tertiary amine chromophore. Moreover, the hyperbranched poly(amino ether ester)s exhibit an aggregation caused quenching (ACQ) fluorescence, solvent induced red‐shifted emission, molecular weight, and temperature dependent emission characters. More interestingly, the hyperbranched poly(amino ether ester)s show extreme acid induced quenching fluorescence phenomenon, and also display good water solubility, specific recognition of Fe3+ ion, low cytotoxicity, and bright cell imaging, which could serve as a microenvironment‐responding fluorescent probe for application in chemical sensing, cell imaging, drug delivery, or disease diagnostics. This research provides a versatile method for the preparation of stimuli‐responsive aliphatic tertiary amine chromophore polymers, and supplies ideas for researchers to explore other unconventional fluorescent polymers for application.

Mechanical response and equilibrium swelling of thermoresponsive copolymer hydrogels

AbstractCovalently crosslinked thermoresponsive (TR) gels form a special class of hydrogels that swell noticeably below their volume phase transition temperature Tc and shrink above Tc. As the critical temperature is weakly affected by the preparation conditions and molar fractions of monomers and crosslinkers in the pre‐gel solution, a facile method to modulate Tc (which is required for biomedical applications of TR gels and their use as temperature‐triggered actuators) is to incorporate relatively small amounts of neutral monomers whose hydrophilicity differs from that of the basic monomers. Although observations on copolymer gels confirm the effectiveness of this method, the molar fractions of comonomers necessary for the tuning of Tc remain unknown. A model was developed for the mechanical response and equilibrium swelling of TR gels. Adjustable parameters in the governing relations were found by fitting equilibrium swelling diagrams for poly(N‐isopropylacrylamide) homopolymer and copolymer gels. Good agreement is demonstrated between the experimental data and the results of simulation. Based on the model, an analytical formula is derived that expresses the volume phase transition temperature in terms of the molar fraction of comonomers. Its ability to predict the critical temperature is confirmed by comparison with observations on several copolymer gels. © 2020 Society of Chemical Industry

Development of a circulating tumor cell-based RNA classifier for patients with castration-resistant prostate cancer: CTC-PCS/PAM50.

e17509 Background: Genomic profiling has strongly impacted the contemporary understanding of prostate cancer (PCa). Clinical trials are now testing the utility of genomic classifiers such as the PCS (You, Ca Res 2016) and PAM50 (Zhao, JAMA Onc 2017) systems to optimize therapy selection. As contemporary tissue is not always readily available, especially in metastatic, castration-resistant PCa (mCRPC), a blood-based test would be better suited for assessing patients and predicting treatment response. Methods: The CTC-RNA assay combines the Thermoresponsive (TR)-NanoVelcro system with the NanoString nCounter platform. This allows for CTC purification and RNA analysis. Using a novel bioinformatics approach that accounts for differences in background signals between tissue and blood, we reconstructed the PCS and PAM50 panels to recapitulate both classifiers in this blood-based assay. A weighted Z-score and nearest centroid classifier were used to calculate gene expression and to assign PCS and PAM50 subtypes. Performance of the revised signatures and CTC-RNA assay was benchmarked on simulated spiked-blood specimens. An initial clinical test was performed using clinically annotated, banked blood specimens within the Translational Oncology Program Blood and Biospecimen Bank. Results: CTC-RNA profiles of C4-2B AR signaling inhibitor (ARSI)-resistant sublines were compared to parental C4-2B. C4-2B ARSI-resistant cells had significantly higher PCS1 Z scores, PCS1 probability, and basal probability compared to the parental C4-2B cells. Blood samples from 34 mCRPC patients prior to initiation of therapy with ARSIs (abiraterone, enzalutamide, or apalutamide) were then analyzed. Samples were classified as PCS1 (n = 3), PCS2 (n = 20), and PCS3 (n = 11); luminal A (n = 12), luminal B (n = 11), and basal (n = 11). The biochemical progression-free survival (bPFS) on ARSI and overall survival (OS) for PCS1/Basal vs. other are shown in the table. Conclusions: The CTC-RNA assay is capable of generating luminal-basal classifications such as those in the PCS and PAM50 systems. Given early data of these classifiers and their potential to guide therapeutic decisions, this approach may be useful as an alternative to biopsy to facilitate such decisions. Larger prospective studies will be needed to confirm and validate its clinical utility. [Table: see text]

Equilibrium swelling of thermo-responsive copolymer microgels.

Thermo-responsive (TR) hydrogels with a lower critical solution temperature swell strongly at temperatures below their volume phase transition temperature Tc and collapse above Tc. Biomedical application of these materials requires tuning the critical temperature in a rather wide interval. A facile method for modulation of Tc is to polymerize the basic monomers with hydrophilic or hydrophobic comonomers. Although the effectiveness of this method has been confirmed by experimental data, molar fractions of comonomers necessary for fine tuning of Tc in macroscopic gels and microgels are unknown. A simple model is developed for the equilibrium swelling of TR copolymer gels. Its adjustable parameters are found by fitting swelling diagrams on several macro- and microgels with N-isopropylacrylamide as a basic monomer. Good agreement is demonstrated between the experimental swelling curves and results of numerical analysis. An explicit expression is derived for the volume phase transition temperature as a function of molar fraction of comonomers. The ability of this relation to predict the critical temperature is confirmed by comparison with observations.

The effect of saccharides on equilibrium swelling of thermo-responsive gels.

Mechanical and optical properties of thermo-responsive (TR) gels change drastically at their volume phase transition temperature. As the critical temperature is strongly affected by the presence of small amounts of additives in aqueous solutions, TR gels can be employed as sensors for detection and recognition of multiple analytes (from specific ions to hazardous biochemicals to pathogenic proteins) and actuators for biomedical applications. A simplified mean-field model is developed for equilibrium swelling of TR gels in aqueous solutions of additives. Its advantage is that the model involves a relatively small (compared with the conventional approaches) number of material constants and accounts for changes in the thermo-mechanical response at transition from the swollen to collapsed state. The ability of the model to describe experimental swelling diagrams and to predict the influence of additives on the equilibrium degree of swelling and the volume phase transition temperature of TR gels is confirmed by comparison of observations on poly(N-isopropylacrylamide) gel in aqueous solutions of saccharides (glucose, sucrose and galactose) with results of numerical analysis.

Fabrication of a Dual-Stimuli-Responsive Supramolecular Micelle from a Pillar[5]arene-Based Supramolecular Diblock Copolymer for Photodynamic Therapy.

A pH and thermo dual-responsive supramolecular diblock copolymer is constructed by host-guest recognition of pillar[5]arene and viologen salt. The host polymer, poly(N,N-dimethylaminoethyl methacrylate) bearing pillar[5]arene as the terminal group (P[5]A-PDMAEMA) is synthesized by atom transfer radical polymerization (ATRP). Guest polymer, ethyl viologen-ended poly(N-isopropylacrylamide) (EV-PNIPAM) is prepared by reversible addition-fragmentation chain transfer polymerization. The supramolecular diblock copolymer can be self-assembled into stable supramolecular nanoparticles in aqueous solution at 40 °C, which show excellent pH and thermo responsiveness. The nanoparticles are further applied in the encapsulation of photosensitizers (pyropheophorbide-a, PhA) for photodynamic therapy (PDT). The dual-responsive nanoparticles can efficiently release PhA in acidic environment at 25 °C. Based on the result of cell experiments, PhA-loaded nanomicelles exhibit excellent PDT efficacy and low dark toxicity toward A549 cells. Thus, this supramolecular diblock copolymer enriches the methodology of constructing stimuli-responsive drug carriers and presents a great potential in PDT.

Abstract 453: A circulating tumor cell assay for dynamic assessment of drug sensitivity in metastatic castration-resistant prostate cancer

Abstract Background: Tissue-based gene signatures can predict clinical behavior in prostate cancer (PC). Our objective was to extend their application to circulating tumor cells (CTCs) and to show that changes in the signature were associated with changes in clinical behavior. Methods: Our approach combined the Thermoresponsive(TR)-NanoVelcro CTC purification system with the Nanostring nCounter system for cellular purification and transcriptomic analysis. The Prostate Cancer Classification System (PCS) panel was modified for use in CTCs. We selected 31 blood samples from 23 PC patients receiving androgen receptor signaling inhibitors (ARSI) and measured the PCS1 Z score (probability). These findings were compared with clinical outcome data (responsiveness/resistance). Results: A modified, 16-gene PCS1 signature was established and validated through a rigorous bioinformatics process. We performed analytical validation of our combined CTC-RNA system to ensure reproducibility and specificity. In patient bloods, ARSI-resistant samples (ARSI-R, n=14) had significantly higher PCS1 Z scores as compared with ARSI-sensitive samples (ARSI-S, n=17) (Rank-sum test, P=0.003). The analyzed bloods contained samples from 8 patients who developed resistance to an ARSI allowing for dynamic measurement of gene expression. Our analysis found that the PCS1 Z score increased at the time that ARSI-resistance emerged (Pairwise T-test, P=0.016). Conclusions:Using this new methodology, contemporary, clinically-relevant gene signatures such as PCS could be measured non-invasively in CTCs. These findings can be used to relate gene expression to clinical drug response. This approach also allowed for measurement of dynamic variations of gene expression in individual patients over time that correlated to ARSI sensitivity. Citation Format: Pai-Chi Teng, Yu Jen Jan, Junhee Yoon, Jie-Fu Chen, Pin-Jung Chen, Nu Yao, Shirley Cheng, Amber Lozano, Michael R. Freeman, Sungyong You, Hsian-Rong Tseng, Edwin M. Posadas. A circulating tumor cell assay for dynamic assessment of drug sensitivity in metastatic castration-resistant prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 453.