Sensitive Poly Research Articles

Sensitive and Flexible Polymeric Strain Sensor for Accurate Human Motion Monitoring.

Flexible electronic devices offer the capability to integrate and adapt with human body. These devices are mountable on surfaces with various shapes, which allow us to attach them to clothes or directly onto the body. This paper suggests a facile fabrication strategy via electrospinning to develop a stretchable, and sensitive poly (vinylidene fluoride) nanofibrous strain sensor for human motion monitoring. A complete characterization on the single PVDF nano fiber has been performed. The charge generated by PVDF electrospun strain sensor changes was employed as a parameter to control the finger motion of the robotic arm. As a proof of concept, we developed a smart glove with five sensors integrated into it to detect the fingers motion and transfer it to a robotic hand. Our results shows that the proposed strain sensors are able to detect tiny motion of fingers and successfully run the robotic hand.

Construction of multifunctional materials by intrachannel modification of NIPA hydrogel with PANI-metal composites

Composites containing conductive polymers and Au and Ag nanoparticles were introduced into the environmentally sensitive poly(N-isopropylacrylamide) hydrogel channels. The composites were synthesized directly in the channels by two phase polymerization procedure. In the first step the unmodified hydrogel was placed in a solution containing the oxidizing agent (HAuCl4 or AgNO3), and in the second step it was placed in a solution of aniline in nitrobenzene. The presence of polyaniline and metal nanoparticles increased conductivity of both types (ionic and electron) while the hydrogel properties, such as: flexibility, plasticity and ability to phase transition, were preserved. The presence of nobel-metal nanostructures added catalytical activity to the new materials. Optical and SEM investigations revealed that polymer-metal composites were uniformly distributed in the entire gel samples. NIPA-PANI-Au composites exhibited a sharp volume phase transition in response to changes in temperature and ionic strength. That behavior was similar to unmodified poly (N-isopropylacrylamide) hydrogel. The new material was electroactive and had electrocatalytical properties towards electrooxidation of ethanol. Electroactivity of the modified gel was a strong function of the swelling ratio; the shrinking process enhanced the voltammetric response.

Synthesis and characterization of CO2-sensitive temperature-responsive catalytic poly(ionic liquid) microgels

A class of poly(ionic liquid) microgels exhibiting CO2-switchable temperature-responsive volume phase transition behavior have been synthesized and used for CO2 fixation.

Drug-mediation formation of nanohybrids for sequential therapeutic delivery in cancer cells

In order to overcome the multidrug resistance (MDR) of tumor cells, it is very important to develop nanocarriers which can effectively load drugs while releasing them in a sequential way. Herein, nanohybrids with such properties have been fabricated by a first loading of one anticancer drug onto a silicate nanodisk (Laponite (LP), 25 nm in diameter and 0.92 nm in thickness) and a subsequent assembly with a pH sensitive poly(N-vinylpyrrolidone) (PVP) as a protective layer, followed by a loading of with another anticancer drug. The resulting nanohybrids (LDPM) present a high drug encapsulation efficiency and long-term colloidal stability. However, if the two drugs are loaded onto LP before PVP decoration, the formed particles tend to form microsized aggregates with poor colloidal stability. In vitro release study indicates that LDPM can deliver the anticancer drugs in a sequential way, which can be further accelerated under acidic microenvironments mimicking both solid tumor and endo-lysosomal compartments, exerting synergistic anticancer cytotoxicity. The drug-mediated formation of nanocarriers may enlighten a design of novel nanoplatform for co-delivery of therapeutic agents, beyond anticancer drugs, in a combinative way for drug delivery applications.

Quantitative Study of the Oligomerization of Yeast Prion Sup35NM Proteins.

The fibrillation of misfolded neurodegenerative disease-related proteins has been extensively studied over the past few decades, but the initial oligomerization has been rarely examined even though some recent evidence indicated that small protein oligomers are more neurotoxic than long protein fibers. It is rather difficult to study the initial oligomerization (nucleation) because most experimental methods, such as the β-sheet-related fluorescence assay and X-ray diffraction, are unable to detect small structureless protein oligomers. In this study, we have successfully developed a method to link a short thermally sensitive poly(N-isopropylacrylamide) (PNIPAM) chain to a model protein, Sup35NM, at a specific 31st residue site (Sup35NM-31m-PNIPAM) via the efficient thiol-ene Michael addition reaction. The oligomerization was studied by a combination of laser light scattering, the thioflavin T assay, and transmission electron microscopy. We found that the lag phase of Sup35NM was delayed from 12 to >24 h under the physiological condition after the PNIPAM linkage. The oligomerization and fibrillation constants decreased from 5.0 × 10-3 to 1.5 × 10-3 h-1 and from 3.0 × 10-2 to 1.8 × 10-2 μM-1 h-1, respectively, presumably because of the steric hindrance introduced by the PNIPAM chain. Moreover, after initiating the oligomerization, we found that the oligomer distribution in the first 6 h repeatedly and quantitatively follows the Smoluchowski coagulation model. Our study paves the way for controllably and quantitatively studying the oligomerization kinetics of amyloidogenic proteins. In addition, by investigating the effects of different small molecules on the oligomerization kinetics, we should be able to screen potential drugs to slow the development of neurodegenerative diseases.

Sensitive electrochemical determination of epinephrine at poly(L-aspartic acid)/electro-chemically reduced graphene oxide modified electrode by square wave voltammetry in pharmaceutics

A simple and sensitive poly(L-aspartic acid)/electrochemically reduced graphene oxide modified glassy carbon electrode, P(L-Asp)/ERGO/GCE, was constructed by electrochemical reduction of GO drop coated on glassy carbon electrode within 2mM L-aspartic acid by cyclic voltammetry in pH6 PBS which give rise to in situ polymerization of L-aspartic acid on electrochemically reduced graphene oxide. Raman, FTIR and UV spectroscopy were used to characterize GO, ERGO, P(L-Asp) and P(L-Asp)/ERGO composites. The P(L-Asp)/ERGO/GCE was used for epinephrine (EP) detection using square wave voltammetry. The electrochemical response of P(L-Asp)/ERGO/GCE was characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and electroactive surface area (ESA) measurements. A significant enhancement in the peak current response of EP was observed accompanied with a negative shift in peak potential at the composite modified electrode compared to the bare electrode. The prepared P(L-Asp)/ERGO/GCE exhibited excellent SWV response towards EP detection in the range of 0.1–110μM with limit of detection and quantification of 0.025 and 0.083μM, respectively. Real sample analysis was carried out in pharmaceutical formulation of EP hydrochloride injection, which revealed good recovery results, 94–109%. The method was further validated by the UV assay and the obtained result confirmed the applicability of the present method for routine analysis. The proposed sensor also displayed good selectivity, repeatability and reproducibility with appreciable long-term stability.

Erythrocyte Membrane-Wrapped pH Sensitive Polymeric Nanoparticles for Non-Small Cell Lung Cancer Therapy.

The application of nano drug delivery systems (NDDSs) may enhance the effectiveness of chemotherapeutic drugs in vivo. However, the short blood circulation time and poor drug release profile in vivo are still two problems with them. Herein, by using red blood cell membrane (RBCm) wrapping and pH sensitive technology, we prepared RBCm wrapped pH sensitive poly(l-γ-glutamylcarbocistein)-paclitaxel (PGSC-PTX) nanoparticles (PGSC-PTX@RBCm NPs), to prolong the circulation time in blood and release PTX timely and adequately in acidic tumor environment. The PGSC-PTX NPs and PGSC-PTX@RBCm NPs showed spherical morphology with average sizes about 50 and 100 nm, respectively. The cytotoxicity of PGSC-PTX@RBCm NPs was considerably decreased compared with that of PGSC-PTX NPs. PTX release from PGSC-PTX and PGSC-PTX@RBCm NPs at pH 6.5 was remarkably higher than those at pH 7.4, respectively. The PGSC-PTX@RBCm NPs exhibited remarkably decreased uptake by macrophages than PGSC-PTX NPs. The area under the curve within 72 h (AUC0-72h) for is significantly higher than PGSC-PTX NPs. The PGSC-PTX@RBCm NPs also showed significantly stronger growth-inhibiting effect on tumor than PGSC-PTX NPs. These results indicated that PGSC-PTX@RBCm NPs have acidic drug release sensitivity, the characteristics of long circulation, and remarkable tumor growth inhibiting effect. This study may provide an effective strategy for improving the antitumor effect of NDDS.

Magnetic and Thermal-sensitive Poly(N-isopropylacrylamide)-based Microgels for Magnetically Triggered Controlled Release.

Magnetically and thermally sensitive poly(N-isopropylacrylamide) (PNIPAAm)/Fe3O4-NH2 microgels with the encapsulated anti-cancer drug curcumin (Cur) were designed and fabricated for magnetically triggered release. PNIPAAm-based magnetic microgels with a spherical structure were produced via a temperature-induced emulsion followed with physical-crosslinking by mixing PNIPAAm, polyethylenimine (PEI), and Fe3O4-NH2 magnetic nanoparticles. Because of their dispersity, the Fe3O4-NH2 nanoparticles were embedded inside the polymer matrix. The amine groups exposed on the Fe3O4-NH2 and PEI surface supported the spherical structure by physically crosslinking with the amide groups of the PNIPAAm. The hydrophobic anti-cancer drug curcumin can be dispersed in water after encapsulation into the microgels. The microgels were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and UV-Vis spectral analysis. Furthermore, magnetically triggered release was studied under an external high frequency magnetic field (HFMF). A significant "burst release" of curcumin was observed after applying the HFMF to the microgels due to the magnetic inductive heating (hyperthermia) effect. This manuscript describes the magnetically triggered controlled release of Cur-PNIPAAm/Fe3O4-NH2 encapsulated curcumin, which can be potentially applied for tumor therapy.

Bioimaging Using Full Field and Contact EUV and SXR Microscopes with Nanometer Spatial Resolution

We present our recent results, related to nanoscale imaging in the extreme ultraviolet (EUV) and soft X-ray (SXR) spectral ranges and demonstrate three novel imaging systems recently developed for the purpose of obtaining high spatial resolution images of nanoscale objects with the EUV and SXR radiations. All the systems are based on laser-plasma EUV and SXR sources, employing a double stream gas puff target. The EUV and SXR full field microscopes—operating at 13.8 nm and 2.88 nm wavelengths, respectively—are currently capable of imaging nanostructures with a sub-50 nm spatial resolution with relatively short (seconds) exposure times. The third system is a SXR contact microscope, operating in the “water-window” spectral range (2.3–4.4 nm wavelength), to produce an imprint of the internal structure of the investigated object in a thin surface layer of SXR light sensitive poly(methyl methacrylate) photoresist. The development of such compact imaging systems is essential to the new research related to biological science, material science, and nanotechnology applications in the near future. Applications of all the microscopes for studies of biological samples including carcinoma cells, diatoms, and neurons are presented. Details about the sources, the microscopes, as well as the imaging results for various objects will be shown and discussed.

Smart membranes with pH-responsive control of macromolecule permeability

Utilization of membranes for separation of macromolecules has gained wide interest in the last decade, especially after the development of smart membranes with tunable properties for improved separation performance. In this work, we fabricated hybrid membranes with variable pore sizes that depend on the pH of the environment. Hybrid membranes were prepared by conformally coating the pore walls of anodic aluminum oxide (AAO) templates with the pH sensitive poly(methylacrylic acid-co-ethylene glycol dimethacrylate) (p(MAA-co-EGDMA)) polymer using initiated chemical vapor deposition (iCVD). Performance of the membranes was investigated under different pH conditions using nanoparticles, polyacrylic acid (PAA) and BSA protein as permeates. Reduced pore sizes at pH 9 due to swollen polymer decreased the permeability of permeates compared to that at pH 3. In addition to size, charge interactions between the polymer surface and permeates affected the permeation. At high pH values, permeation of BSA was reduced due to reduced pore size and the electrostatic interactions with the polymer.

Bench-Top Fabrication of an All-PDMS Microfluidic Electrochemical Cell Sensor Integrating Micro/Nanostructured Electrodes.

In recent years, efforts in the development of lab-on-a-chip (LoC) devices for point-of-care (PoC) applications have increased to bring affordable, portable, and sensitive diagnostics to the patients’ bedside. To reach this goal, research has shifted from using traditional microfabrication methods to more versatile, rapid, and low-cost options. This work focuses on the benchtop fabrication of a highly sensitive, fully transparent, and flexible poly (dimethylsiloxane) (PDMS) microfluidic (μF) electrochemical cell sensor. The μF device encapsulates 3D structured gold and platinum electrodes, fabricated using a shape-memory polymer shrinking method, which are used to set up an on-chip electrochemical cell. The PDMS to PDMS-structured electrode bonding protocol to fabricate the μF chip was optimized and found to have sufficient bond strength to withstand up to 100 mL/min flow rates. The sensing capabilities of the on-chip electrochemical cell were demonstrated by using cyclic voltammetry to monitor the adhesion of murine 3T3 fibroblasts in the presence of a redox reporter. The charge transfer across the working electrode was reduced upon cell adhesion, which was used as the detection mechanism, and allowed the detection of as few as 24 cells. The effective utilization of simple and low cost bench-top fabrication methods could accelerate the prototyping and development of LoC technologies and bring PoC diagnostics and personalized medicine to the patients’ bedside.

Modeling of drug release behavior of pH and temperature sensitive poly(NIPAAm-co-AAc) IPN hydrogels using response surface methodology and artificial neural networks

An interpenetrated polymer network (IPN) poly(NIPAAm-co-AAc) hydrogel was synthesized by two polymerization method: emulsion and solution polymerization. The pH- and temperature-sensitive hydrogel was loaded by swelling with riboflavin drug, a B2 vitamin. The release of riboflavin as a function of time has been achieved under different pH and temperature environments. The determination of experimental conditions and the analysis of drug delivery results were achieved using response surface methodology (RSM). In this work, artificial neural networks (ANNs) in MATLAB were also used to model the release data. The predictions from the ANN model, which associated input variables, produced results showing good agreement with experimental data compared to the RSM results.

Thermo-responsive nanoarrays of silver nanoparticle, silicate nanoplatelet and PNiPAAm for the antimicrobial applications

The ternary nanohybrids of silver nanoparticles (AgNPs) in combination with silicate nanoplatelets (NSP) and thermally sensitive poly(N-isopropylacrylamide) (PNiPAAm) were fabricated for antibacterial applications. PNiPAAm were chemically grafted on the NSP by atom-transfer radical polymerization (ATRP) via polymerizing N-isopropylacrylamide monomers with sol-gel linkers (BBTES). The nanoparticles of AgNPs then were adsorbed on NSP-PNiPAAm nanosheets through in situ reduction reaction of AgNO3 in aqueous dispersion. The particle sizes of AgNPs were estimated to be 7–12nm in diameter with different composition ratios of AgNPs to NSP-PNiPAAm, evaluated by transmission electron microscope (TEM). The nanohybrids of AgNP/NSP-PNiPAAm exhibited the unique property of lowest critical solution temperature (LCST) at 32°C. The thermo-responsive antibacterial efficacy of the ternary nanohybrids was demonstrated by Bacillus subtilis (B. subtilis) and Escherichia coli (E. coli) at lower than the LCST (28°C) and higher than the LCST (37°C). The result show that the great antibacterial ability was observed in the hydrophilic bacteria (B. subtilis) at 28°C. In contrast, the excellent antibacterial ability was found in the hydrophobic bacteria (E. coli) at 37°C, due to the surface energy modulation of AgNP/NSP-PNiPAAm. The tailoring of silver-containing ternary nanohybrids allow the new antibacterial nanomaterials to selectively affect the surface of bacteria by varying temperature.

Fabrication and in vitro evaluation of novel pH‐sensitive poly (2‐methoxyethyl methacrylate‐co‐itaconic acid) microgels

AbstractThe present work focused on the synthesis and evaluation of cross‐linked poly(2‐methoxyethyl methacrylate‐co‐itaconic acid) [p(MEMA‐co‐IA)] microgels for controlled and extended drug delivery, in an attempt to improve the bioavailability of the drugs and to get maximum therapeutic benefits. A series of p(MEMA‐co‐IA) microgels were prepared by modified free‐radical suspension polymerization using ethylene glycol dimethacrylate as cross‐linker. Characterization was performed through FTIR, TGA, DSC, XRD, DLS and SEM. pH responsiveness was evaluated by equilibrium swelling studies in phosphate buffer solutions of different pH values (pH 1.2, 4, 6.5, and 7.4) with constant ionic strength. To demonstrate the potential use of microgels for drug delivery, esomeprazole magnesium trihydrate (EMT) was loaded as model drug and in vitro dissolution studies were performed. FTIR and thermal analysis confirmed the formation of cross‐linked p(MEMA‐co‐IA) microgels. XRD indicated dispersion of drug into the network at molecular level. SEM illustrated smooth, round and uniformly distributed microspheres. A remarkably higher swelling at higher pH values (pH 6.5 and 7.4) compared to pH 1.2 demonstrated the pH‐responsive nature of the microgels. All the formulations showed pH‐dependent drug release following Higuchi with non‐fickian mechanism of drug diffusion. In light of the results obtained from this study, it was concluded that p(MEMA‐co‐IA) microgels have potential to release drug in controlled manner responsive to pH of the external environment.

Shape Memory Polymer Composites of Poly(styrene-b-butadiene-b-styrene) Copolymer/Liner Low Density Polyethylene/Fe3O4 Nanoparticles for Remote Activation

Magnetically sensitive shape memory poly(styrene-b-butadiene-b-styrene) copolymer (SBS)/liner low density polyethylene (LLDPE) composites filled with various contents of Fe3O4 nanoparticles were prepared. The influence of the Fe3O4 nanoparticles content on the thermal properties, mechanical properties, fracture morphology, magnetic behavior, and shape memory effect of SBS/LLDPE/Fe3O4 composites was systematically studied in this paper. The results indicated that homogeneously dispersed Fe3O4 nanoparticles ensured the uniform heat generation and transfer in the alternating magnetic field, and endowed the SBS/LLDPE/Fe3O4 composites with an excellent magnetically responsive shape memory effect. When the shape memory composites were in the alternating magnetic field (f = 60 kHz, H = 21.21 kA·m−1), the best shape recovery ratio reached 99%, the shape retention ratio reached 99.4%, and the shape recovery speed increased significantly with the increment of Fe3O4 nanoparticles. It is anticipated that tagging products with this novel shape memory composite is helpful for the purpose of an intravascular delivery system in Micro-Electro-Mechanical System (MEMS) devices.

Synthesis of Thermogelling Poly(N-isopropylacrylamide)-graft-chondroitin Sulfate Composites with Alginate Microparticles for Tissue Engineering.

Injectable biomaterials are defined as implantable materials that can be introduced into the body as a liquid and solidify in situ. Such materials offer the clinical advantages of being implanted minimally invasively and easily forming space-filling solids in irregularly shaped defects. Injectable biomaterials have been widely investigated as scaffolds for tissue engineering. However, for the repair of certain load-bearing areas in the body, such as the intervertebral disc, scaffolds should possess adhesive properties. This will minimize the risk of dislocation during motion and ensure intimate contact with the surrounding tissue, providing adequate transmission of forces. Here, we describe the preparation and characterization of a scaffold composed of thermally sensitive poly(N-isopropylacrylamide)-graft-chondroitin sulfate (PNIPAAM-g-CS) and alginate microparticles. The PNIPAAm-g-CS copolymer forms a viscous solution in water at RT, into which alginate particles are suspended to enhance adhesion. Above the lower critical solution temperature (LCST), around 30 °C, the copolymer forms a solid gel around the microparticles. We have adapted standard biomaterials characterization procedures to take into account the reversible phase transition of PNIPAAm-g-CS. Results indicate that the incorporation of 50 or 75 mg/mlalginate particles into 5% (w/v) PNIPAAm-g-CS solutions quadruple the adhesive tensile strength of PNIPAAm-gCS alone (p<0.05). The incorporation of alginate microparticles also significantly increases swelling capacity of PNIPAAm-g-CS (p<0.05), helping to maintain a space-filling gel within tissue defects. Finally, results of the in vitro toxicology assay kit, 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) and Live/Dead viability assay indicate that the adhesive is capable of supporting the survival and proliferation of encapsulated Human Embryonic Kidney (HEK) 293 cells over 5 days.

Influence of Charged Groups on the Structure of Microgel and Volume Phase Transition by Dielectric Analysis

The thermally sensitive charged poly(N-isopropylacrylamide-co-methacrylic acid) (P(NIPAM-co-MAA)) spherical microgel was prepared and their temperature-dependent volume phase transition behavior was systematically studied by analyzing the dielectric spectroscopy theoretically over a frequency range from 40 Hz to 110 MHz. It was found that the dielectric relaxation of the charged P(NIPAM-co-MAA) microgel drastically changed between 30 and 35 °C, and was significantly different from that of neutral PNIPAM microgels recently published in Soft Matter. The relaxation mechanism was speculated and the relaxation parameters were fitted after successfully eliminating the electrode polarization at low-frequency. On the basis of this, the differences in the structure, swelling ability and dehydration dynamics between charged P(NIPAM-co-MAA) and neutral PNIPAM microgels were compared. Although both of the two microgels showed the same changing trend around the volume phase transition temperature (VPTT), VPTT of charg...

PHB-Based Gels as Delivery Agents of Chemotherapeutics for the Effective Shrinkage of Tumors.

Injectable thermogel to deliver chemotherapeutics in a minimally invasive manner and to achieve their long term sustained release at tumor sites to minimize side effects is attractive for chemotherapy and precision medicine, but its rational design remains a challenge. In this work, a copolymer with natural biodegradable poly[(R)-3-hydroxybutyrate] (PHB), hydrophilic poly(ethylene glycol), and temperature sensitive poly(propylene glycol) blocks linked by urethane linkages is designed to show thermogelling characteristics which are beneficial for minimally invasive injection and safe degradation. This thermogelling polymer possesses in vitro biocompatibility with very low cyto-toxicity in HEK293 cells. Furthermore, it is able to form the gel to achieve the controllable release of paclitaxel (PTX) and doxorubicin (DOX) by adjusting polymer concentrations. A rodent model of hepatocarcinoma has been performed to demonstrate the in vivo applications of this PHB-based thermogel. The drug-loaded thermogel has been intratumorally injected and both PTX-loaded and DOX-loaded thermogel have significantly slowed down tumor growth. This work represents the first time that injectable PHB thermogels have possessed good controllable release effect of chemotherapeutics against the in vivo model of tumors and will benefit various applications, including on-demand drug delivery and personalized medicine.

Voltammetric determination of polyphenolic content in pomegranate juice using a poly(gallic acid)/multiwalled carbon nanotube modified electrode.

A simple and sensitive poly(gallic acid)/multiwalled carbon nanotube modified glassy carbon electrode (PGA/MWCNT/GCE) electrochemical sensor was prepared for direct determination of the total phenolic content (TPC) as gallic acid equivalent. The GCE working electrode was electrochemically modified and characterized using scanning electron microscope (SEM), cyclic voltammetry (CV), chronoamperometry and chronocoulometry. It was found that gallic acid (GA) exhibits a superior electrochemical response on the PGA/MWCNT/GCE sensor in comparison with bare GCE. The results reveal that a PGA/MWCNT/GCE sensor can remarkably enhance the electro-oxidation signal of GA as well as shift the peak potentials towards less positive potential values. The dependence of peak current on accumulation potential, accumulation time and pH were investigated by square-wave voltammetry (SWV) to optimize the experimental conditions for the determination of GA. Using the optimized conditions, the sensor responded linearly to a GA concentration throughout the range of 4.97 × 10−6 to 3.38 × 10−5 M with a detection limit of 3.22 × 10−6 M (S/N = 3). The fabricated sensor shows good selectivity, stability, repeatability and (101%) recovery. The sensor was successfully utilized for the determination of total phenolic content in fresh pomegranate juice without interference of ascorbic acid, fructose, potassium nitrate and barbituric acid. The obtained data were compared with the standard Folin–Ciocalteu spectrophotometric results.

PH, temperature and reduction multi-responsive polymeric microspheres as drug delivery system for anti-tumor drug: Effect of middle hollow layer between pH and reduction dual-responsive cores and temperature sensitive shells

Multi-responsive polymeric microspheres have attracted more and more interest as drug delivery system (DDS) for anti-tumor drugs because they could achieve “on-demand” drug release, triggered by the tumor micro-environment. Here the pH, temperature and reduction multi-stimuli responsive polymeric microspheres were fabricated via distillation–precipitation polymerization technique, with or without the middle hollow layer between their pH and reduction responsive poly(methacrylic acid) (PMAA) cores and temperature sensitive poly(N-isopropylacrylamide) (PNIPAM) shells. The effect of the hollow layer on their drug loading and drug release performance was investigated in detail. It was found that the PMAA/PNIPAM yolk/shell microspheres with hollow layer possessed a higher drug loading capacity, while the PMAA/PNIPAM core/shell microspheres without hollow layer exhibited a better controlled release behavior. This understanding must be helpful on designing intelligent anti-tumor DDS.