Gel Nanoparticles Research Articles

The long term stability of silica nanoparticle gels in waters of different ionic compositions and pH values

The use of silica nanoparticles for grouting underground tunnels offers an environmentally friendly option compared to organic grouting materials. Silica sols are commercially available and when mixed with an accelerator (salt) they form gels in a predetermined time. While much research has been focused on the practical implementation of silica sols in grouting as well as on the development of physical parameters such as viscosity and strength development, little is known about the long term stability of the resultant silica gels. When placed in rock fractures, parameters such as pH and ionic composition of groundwater may affect the long term stability and functionality of the gels.In this article we use a newly designed test equipment to simulate the behaviour of silica gels when water passes through the gel structure for up to 488 days. The pH and ionic composition of the water is varied to simulate environments that can be experienced by gels used for grouting applications. Results in the form of ionic composition, volume, and pH of leached water were used to evaluate and predict the lifetime of silica gels. The overall results show that several factors such as water flow and the nature of salt, so called accelerator used for gelling have significant effect on the gel life time. Furthermore, it is shown that the accelerator ions leach from the gels; however, the extent to which they are released from the gel depends upon the salt type. From these results we have predicted the lifetime of the 100 mL gels used in our experiments by using a simple numerical model. The predictions show that the total dissolution time for 100 mL gels are up to hundreds of years.

Chiromagnetic nanoparticles and gels.

Chiral inorganic nanostructures have high circular dichroism, but real-time control of their optical activity has so far been achieved only by irreversible chemical changes. Field modulation is a far more desirable path to chiroptical devices. We hypothesized that magnetic field modulation can be attained for chiral nanostructures with large contributions of the magnetic transition dipole moments to polarization rotation. We found that dispersions and gels of paramagnetic Co3O4 nanoparticles with chiral distortions of the crystal lattices exhibited chiroptical activity in the visible range that was 10 times as strong as that of nonparamagnetic nanoparticles of comparable size. Transparency of the nanoparticle gels to circularly polarized light beams in the ultraviolet range was reversibly modulated by magnetic fields. These phenomena were also observed for other nanoscale metal oxides with lattice distortions from imprinted amino acids and other chiral ligands. The large family of chiral ceramic nanostructures and gels can be pivotal for new technologies and knowledge at the nexus of chirality and magnetism.

Boosting chiral nanoparticle responses

Magnetic Materials Optical nanomaterials that combine chirality and magnetism are useful for magneto-optics and as chiral catalysts. Although chiral inorganic nanostructures can exhibit high circular dichroism, modulating this optical activity has usually required irreversible chemical changes. Yeom et al. synthesized paramagnetic cobalt oxide (Co3O4) nanoparticles with l- and d-cysteine surface ligands. These ligands created chiral distortions of the crystal lattices, and this anisotropy led to much stronger chiroptical activity. The circular dichroism in the ultraviolet of nanoparticle gels could be modulated with magnetic fields of ∼1.5 tesla. Science , this issue p. [309][1] [1]: /lookup/doi/10.1126/science.aao7172

Unusual multiscale mechanics of biomimetic nanoparticle hydrogels

Viscoelastic properties are central for gels and other materials. Simultaneously, high storage and loss moduli are difficult to attain due to their contrarian requirements to chemical structure. Biomimetic inorganic nanoparticles offer a promising toolbox for multiscale engineering of gel mechanics, but a conceptual framework for their molecular, nanoscale, mesoscale, and microscale engineering as viscoelastic materials is absent. Here we show nanoparticle gels with simultaneously high storage and loss moduli from CdTe nanoparticles. Viscoelastic figure of merit reaches 1.83 MPa exceeding that of comparable gels by 100–1000 times for glutathione-stabilized nanoparticles. The gels made from the smallest nanoparticles display the highest stiffness, which was attributed to the drastic change of GSH configurations when nanoparticles decrease in size. A computational model accounting for the difference in nanoparticle interactions for variable GSH configurations describes the unusual trends of nanoparticle gel viscoelasticity. These observations are generalizable to other NP gels interconnected by supramolecular interactions and lead to materials with high-load bearing abilities and energy dissipation needed for multiple technologies.

Antibacterial Effect of Two Nano Zinc Oxide Gel Preparations Compared to Calcium Hydroxide and Chlorhexidine Mixture.

Introduction:The aim of this study was to compare the antibacterial effects of two gels containing zinc oxide and zinc oxide/silver nanoparticles and a mixture of calcium hydroxide and 0.12% chlorhexidine as intracanal medicaments in root canals contaminated with Enterococcus faecalis (E. faecalis) at different time intervals. Methods and Materials:After preparation and culturing of E. faecalis in 132 single root teeth, the initial count of bacteria was performed. Then, different materials as intracanal medicaments were used in periods of 3, 7 and 14 days (group 1: calcium hydroxide with 0.12% CHX paste; group 2 zinc oxide nanoparticles gel; group 3: zinc oxide/silver nanoparticles gel; group 4: normal saline as the control group). After the specified time, intracanal medicament was removed and the final count of bacteria was performed. Antibacterial effect of materials was counted by measuring the percentage reduction in the colony counts (RCC). Data were analyzed using the descriptive statistics (Mean±SD) and multi-factorial analysis of variance (by taking into account the effect of the time factor on the dependent variable). Results:There were no statistically significant differences among mean RCC of different time intervals in each group (P=0.09). However, the differences in mean RCC of different dressing materials were significant (P<0.001). The effect of interaction between time and materials was significant (P=0.015). Comparison of the antibacterial effects of experimental agents at different time intervals showed that the mean RCC in group 1 was higher than other groups (P<0.001). The difference in antibacterial effect between groups 2 and 3 was not significant (P>0.05). The minimum antibacterial effect was observed in group 4 (P<0.0001). Conclusions:The mixture of calcium hydroxide/chlorhexidine as an intracanal medicament was more effective than zinc oxide and zinc oxide/silver nanoparticles gels.

Thermally reversible nanoparticle gels with tuneable porosity showing structural colour.

We present colloidal gels formed from dispersions of PEG- and PEG+DNA-coated silica nanoparticles showing structural colour. The PEG- and PEG+DNA-coated silica colloids are functionalized using exclusively covalent bonds in aqueous conditions. Both sets of colloids self-assemble into thermally-reversible colloidal gels with porosity that can be tuned by changing the colloid volume fraction, although the interaction potentials of the colloids in the two systems are different. Confocal microscopy and image analysis tools are used to characteraize the gels' microstructures. Optical reflection spectroscopy is employed to study the underlying gel nanostructure and to characterize the optical response of the gels. X-ray nanotomography is used to visualize the nanoscale phase separation between the colloid-rich gel branches and the colloid-free gel pores. These nanoparticle gels open new routes for creating structural colour where the gel structure is decoupled from the form factor of the individual colloids. This approach can be extended to create unexplored three dimensional macroscale materials with length scales spanning hundreds of nanometers, which has been difficult to achieve using other methods.

Clinical Evaluation of Nano-Hydroxyapatite as Dentin Desensitizer

Objectives: This clinical study was conducted to evaluate the efficiency of nano-hydroxyapatite (n-HAp) in reducing dentin hypersensitivity individually or combined with fluoride. Materials and methods: Forty hypersensitive teeth from 10 patients with hypersensitive symptoms were treated using hydroxyapatite nanoparticles (nHAp) gel at different concentrations/ sodium fluoride (NaF) containing according to four treatment groups: Group 1; 15% nHAp + 1% NaF, Group 2; 15% nHAp, Group 3;25% nHAp+ 1% NaF, Group 4; 25% nHAp. The initial sensitivity levels were recorded using a verbal rating scale (VRS) and visual analogue scale (VAS) at the baseline visit. The responses were evaluated at 0, 1 day, 1, 2 and 4 weeks respectively for all groups. Results: There was a high statistical significant differences between pain scores before and after treatment for all treated groups. There was statistically significantly high difference between 25% nHAp and the other groups, as they need 4 applications for complete relief while 25% nHAp needs only 3 applications. Conclusion: Nano-hydroxyapatite with 25% concentration was the most effective in alleviating the hypersensitivity symptoms.

In situ hydrosilane reduction and preparation of gold nanoparticle–gel glass composites with nonlinear optical properties

Gold nanoparticles were reduced in situ by a new hydrosilane reductant in organosilicon oligomer to fabricate nonlinear optical limiting materials.

A versatile method for the selective core-crosslinking of hyaluronic acid nanogels via ketone-hydrazide chemistry: from chemical characterization to in vivo biodistribution.

The development of biopolymer-based nanogels has gained particular interest to achieve successful delivery of therapeutics for the treatment of various diseases, such as cancer, infection and diabetes. Herein, we report a new and simple methodology for the covalent stabilization of self-assembled gel nanoparticles based on hyaluronic acid (HA) modified with a thermoresponsive ketone-functional copolymer. This relies on the selective formation of hydrazone crosslinks with bishydrazides within the globular domains of the copolymer chains formed above the cloud point temperature. This approach allows tuning of the crosslinking density by varying the dihydrazide crosslinker to ketone molar ratio. The size distributions and morphology of the nanogels were assessed using dynamic light scattering (DLS), cryo-transmission and scanning electron microscopy. In vitro cellular uptake in several cancer cells and in vivo biodistribution of the nanogels in different mouse tumor models were then explored to assess the effectiveness of this crosslinking strategy. The data from these experiments show prolonged blood circulation, longer than 24 hours, for the crosslinked nanogels and high tumor accumulation.

Chitosan Nanoparticles as a Mucoadhesive Drug Delivery System for Ocular Administration.

Pharmaceutical approaches based on nanotechnologies and the development of eye drops composed of the mucoadhesive polymers chitosan and hyaluronic acid are emerging strategies for the efficient treatment of ocular diseases. These innovative nanoparticulate systems aim to increase drugs’ bioavailability at the ocular surface. For the successful development of these systems, the evaluation of mucoahesiveness (the interaction between the ocular delivery system and mucins present on the eye) is of utmost importance. In this context, the aim of the present work was to investigate the mucoadhesivity of a novel nanoparticle eye drop formulation containing an antibiotic (ceftazidime) intended to treat eye infections. Eye drop formulations comprised a polymer (hydroxypropyl) methyl cellulose (HPMC) 0.75% (w/v) in an isotonic solution incorporating chitosan/sodium tripolyphosphate (TPP)-hyaluronic acid-based nanoparticles containing ceftazidime. The viscosity of the nanoparticles, and the gels incorporating the nanoparticles were characterized in contact with mucin at different mass ratios, allowing the calculation of the rheological synergism parameter (∆η). Results showed that at different nanoparticle eye formulation:mucin weight ratios, a minimum in viscosity occurred which resulted in a negative rheological synergism. Additionally, the results highlighted the mucoadhesivity of the novel ocular formulation and its ability to interact with the ocular surface, thus increasing the drug residence time in the eye. Moreover, the in vitro release and permeation studies showed a prolonged drug release profile from the chitosan/TPP-hyaluronic acid nanoparticles gel formulation. Furthermore, the gel formulations were not cytotoxic on ARPE-19 and HEK293T cell lines, evaluated by the metabolic and membrane integrity tests. The formulation was stable and the drug active, as shown by microbiological studies. In conclusion, chitosan/TPP-hyaluronic acid nanoparticle eye drop formulations are a promising platform for ocular drug delivery with enhanced mucoadhesive properties.

The Healing Effect of Chitosan Supported Nano-CeO2 on Experimental Excisional Wound Infected with Pseudomonas aeruginosa in Rat

Objective- The healing effect of chitosan supported cerium oxide nanoparticles (nano-CeO2) on cutaneous experimental excisional wound infected with pseudomonas aeruginosa was studied in rat. Design- Experimental Study. Animals- Sixty male albino rats. Procedures- The chitosan supported nano-CeO2 hydrogel was prepared and characterized using Fourier-transform infrared spectroscopy (FT-IR), Energy Dispersive X-ray Spectroscopy (EDX), X-ray powder diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The wound was infected with p. aeruginosa and in positive control (PC) group it was treated with silver sulfadiazine ointment with no treatment in negative control (NC) group. The infected wound was treated with chitosan suspension-gel, cerium oxide nanoparticles solution or chitosan supported-CeO2 nanoparticle gel in the treatment groups. The rats were randomized into five groups (n=12). Each group was subdivided into three subgroups of four animals each and studied 3, 7 and 14 days post-wounding. Results- Plantimetry, histopathological assessments and hydroxyprolin content showed better and faster healing of the wounds in the treatment groups, particularly in chitosan supported-CeO2 nanoparticle gel (ChCe) group compared to the NC group (P< 0.05). Using by Ferric Reducing Antioxidant Power (FRAP) the total antioxidant capacity was statistically higher in treatment groups compared to NC group (p< 0.05). The bacterial numbers were significantly lower in ChCe and cerium oxide nanoparticles solution (Ce) groups compared to chitosan (CH) group on day 3 post-wounding (P< 0.05). Conclusion and Clinical Relevance-Topical application of the chitosan supported nano-CeO2 particles on the infected wound enhanced tissue total antioxidant capacity, reduced the bacterial count, accelerated proliferation and migration of fibroblasts and keratinocytes, increased hydroxyproline level and neovascularization scale of the healing wound. Chitosan supported nano-CeO2 hydrogel could be suggested as an alternative therapy for treating of the infected wound.

TRANSDERMAL PATCH OF RAMIPRIL LOADED CHITOSAN NANOPARTICLES DISPERSED IN CARBOPOL GEL

The main aim to improve the systemic bioavailability of Ramipril by the design of transdermal drug delivery based on chitosan nanoparticles dispersed into gels. When chitosan nanoparticles dispersed into gels consisting of poloxamer and carbopol the resulting formulation exhibited thixotropic behavior with a prolonged drug release properties. Our study demonstrated that the designed nanoparticles gel transdermal delivery system has a potential to improve the systemic bioavailability and the therapeutic efficacy of Ramipril loaded chitosan nanoparticles dispersed in carbopol gels. There is no incompatibility between drug and polymers by performing FTIR and DSC. To characterize the rate controlling membrane of transdermal patches. The thickness ranged between TNPGF1 to F9 0.11 ± 0.05 mm to 0.19 ± 0.07 mm, which indicates that they are uniform in thickness. The different batches of formulations weights variations were relatively good uniformity of weight variations among the various batches was observed, with all formulations and ranged from 1.40 ± 1.2% to 1.78 ± 2.0%. The flatness study showed that all the formulations had the same strip length before and after their cuts, indicating 99% flatness. The tensile strength of the TNPGF1 to TNPGF9 shows the 10.14 ± 1.19 to 12.78 ± 2.45 shows the excellent viscosity. The total amount of drug is present in the transdermal patches of TNPGF1 to TNPGF9 was found to be 90.5 ± 0.3 % to 98.5 ± 0.1 %. In-vitro Franz’s diffusion drug Release Studies of among all formulations best formulation TNPGF6. The drug release through the transdermal patches of Ramipril, follows first order kinetics with diffusion controlled mechanism. Keywords: Ramipril, Nanoparticles, Gels, Folding endurance, Tensile strength.Â

Release Behavior and Antibacterial Activity of Chitosan/Alginate Blends with Aloe vera and Silver Nanoparticles.

Aloe vera is a perennial plant employed for medical, pharmaceutical and cosmetic purposes that is rich in amino acids, enzymes, vitamins and polysaccharides, which are responsible for its therapeutic properties. Incorporating these properties into a biopolymer film obtained from alginate and chitosan allowed the development of a novel wound dressing with antibacterial capacity and healing effects to integrate the antibacterial capacity of silver nanoparticles with the healing and emollient properties of Aloe vera gel. Three alginate-chitosan matrices were obtained through blending methods using different proportions of alginate, chitosan, the Aloe vera (AV) gel and silver nanoparticles (AgNps), which were incorporated into the polymeric system through immersion methods. Physical, chemical and antibacterial characteristics were evaluated in each matrix. Interaction between alginate and chitosan was identified using the Fourier transform infrared spectroscopy technique (FTIR), porosity was studied using scanning electron microscopy (SEM), swelling degree was calculated by difference in weight, Aloe vera gel release capacity was estimated by applying a drug model (Peppas) and finally antibacterial capacity was evaluated against S. Aureus and P. aeruginosa. Results show that alginate-chitosan (A (1:3 Chit 1/Alg 1); B (1:3 Chit 1.5/Alg 1) and C (3:1 Chit 1/Alg 1/B12)) matrices with Aloe vera (AV) gel and silver nanoparticles (AgNps) described here displayed antibacterial properties and absorption and Aloe vera release capacity making it a potential wound dressing for minor injuries.

Nanoparticle Gels Obtained from Hardwood and Softwood Bark for Reinforcing of Paper

For reinforcing of paper, nanoparticle gels from black alder, birch and pine bark were obtained. Non-extracted bark and that extracted in biorefinery were used. For producing nanoparticles, the materials were destructed using the thermocatalytic destruction method and then dispersed in water medium in a ball mill. At a sufficient concentration, gel-like dispersions were obtained, which contained nanoparticles with the size ~300 nm. The effect of nanoparticle gels on the properties of paper sheets was investigated by introducing the dissolved gels in paper furnish and by covering both sides of paper sheets with nanoparticle gel coatings. It has been established that the nanoparticle fillers increase the tensile and burst strength. The nanoparticle fillers from extracted bark increase the mechanical indices to a higher extent. The coatings from nanoparticle gels considerably improve the Gurley air resistance of paper and increase the mechanical indices of paper sheets, especially burst strength. The effect of nanoparticle gel coatings is dependent on the coating thickness and gel concentration. The coatings decrease the tensile strength in a wet state.

COMPARISON BETWEEN LOCAL APPLICATION OF DOXYCYCLINE LOADED NANOPARTICLES AND CONVENTIONAL DOXYCYCLINE GEL ON MATRIX METALLOPROTEINASE 1 AND BONE DENSITY IN CHRONIC PERIODONTITIS

Background & Objective: Nanoparticles have received considerable attention in recent years. This study was conducted to compare between doxycycline loaded nanoparticles (DLNs) and conventional doxycycline gel (CDG) in management of chronic periodontitis (CP). Materials and Methods: This randomized, split mouth study was conducted on 40 sites among 20 patients with chronic periodontitis. The sites were randomly allocated into a control group, receiving scaling and root planing (SRP) plus CDG, and an experimental group, receiving SRP plus DLNs. Clinical parameters and levels of matrix metalloproteinase 1 (MMP1) were assessed at baseline, 1, 3 and 6 months post treatment. Bone density was also assessed at baseline and 6 months after treatment. Results: The results, following the use of both treatment gel formulas, showed a statistically significant reduction in all tested clinical parameters and levels of MMP1 at 1, 3 and 6 months post treatment along with significant increase in bone density after 6 months. However, DLNs treatment achieved a significant reduction not only in clinical parameters but also in MMP1 as compared to CDG treated group. In addition, The DLNs showed a significant bone formation as compared to CDG group.Conclusion: DLNs shows promise as adjunctive local therapy for management of patients with chronic periodontitis.Clinical Relevance: Scientific Rationale for Study: Evaluating the effect of doxycycline loaded nanoparticles gel and conventional doxycycline gel on treatment of chronic periodontitis. Principal Findings: Findings from this randomized, split mouth study of 40 sites among 20 patients with chronic periodontitis supported the potential of doxycycline loaded nanoparticles and conventional doxycycline gel for providing an effective therapy for chronic periodontitis, along with improving clinical parameter, bone density and decreasing matrix metalloproteinase 1. Practical Implications: Doxycycline loaded nanoparticles are proved to be more effective than conventional doxycycline gel as an adjunctive treatment of chronic periodontitis.

Formulation and development of Silybin loaded solid lipid nanoparticle enriched gel for irritant contact dermatitis

The purpose of the present research was to develop Silybin loaded solid lipid nanoparticle gel (SIL-SLN gel) for irritant contact dermatitis (ICD). ICD is associated with reduced skin water content, emerging in dry skin condition and relapsing eczema. SIL is a naturally occurring flavones, which shows antioxidant activity and helps in the treatment of ICD. In this study, the SLN was prepared by the ultrasonic probe sonication method and further evaluated for particle size and entrapment efficiency. Results of optimized batch showed mean particle size 139 ± 0.35 nm and entrapment efficiency 90.97 ± 0.91%. Optimized batch was freeze dried and characterized by field emission scanning electron microscopy (FE-SEM), it shows particles are in nano range, with spherical morphology and smooth surface. Finally, the SLN was incorporated into gel for convenient topical application. The SIL-SLN-gel were evaluated for in-vitro skin occlusivity, skin irritation and ex-vivo diffusion and deposition study and further compared with SIL-plain gel. Efficacy of gel on dinitrochlorobenzene (DNCB) induced ICD mice were evaluated by skin water content, ear swelling and histopathology. Ex-vivo study of SIL-SLN gel exhibited prolonged drug release, whereas the skin irritation study shows no irritancy. In DNCB induced ICD mice SIL-SLN gel showed higher efficacy than SIL-plain gel.

Encapsulation of Rosmarinus officinalis essential oils in chitosan-benzoic acid nanogel with enhanced antibacterial activity in beef cutlet against Salmonella typhimurium during refrigerated storage

In the present study, encapsulation by chitosan (CS)–benzoic acid (BA) nanogel was used to improve antioxidant and antimicrobial activity as well as stability of the Rosmarinus officinalis essential oils (REOs). The mean diameter of the gel nanoparticles produced was below 100 nm with a uniform size distribution and spherical shape. Subsequently, the antibacterial activity of the coatings including free REOs and CS–BA nanogel-encapsulated REOs against Salmonella typhimurium was evaluated on inoculated beef cutlet samples. The results obtained showed that the CS–BA nanogel-encapsulated REOs coating was more effective compared with the free REOs in reducing Salmonella population on beef cutlets under refrigerated storage. Nano-encapsulation at 2 mg/g beef cutlet had the most promising effect on reducing the pathogens population. Moreover, nano-encapsulation led to least impact on increasing pH of the beef cutlet samples. CS–BA nanogel-encapsulated REOs at 0.5 mg/g beef cutlet had minimum effects on the color values during storage. Overall, the results obtained revealed that due to the volatility and instability of the EOs when exposed to environmental factors, their encapsulation considerably improved their performance. In conclusion, REOs in form of nanogel can be used as an effective tool to reduce foodborne pathogens like S. typhimurium and in extending meat shelf life.

Dense and crack-free mullite films obtained from a hybrid sol–gel/dip-coating approach

Abstract

Enhanced topical penetration, system exposure and anti-psoriasis activity of two particle-sized, curcumin-loaded PLGA nanoparticles in hydrogel

Psoriasis is an immune-mediated skin disorder, which is triggered by the aberrant activation of dendritic cells in skin. This activation is followed by the complex interaction between the immune cells in the skin and keratinocyte in the epidermis. To improve the conditions of poor aqueous solubility and chemical stability, overcome skin barriers, and enhance in vivo anti-psoriatic activity, curcumin (Cur) loaded poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) were fabricated and administered by topical route to treat imiquimod (IMQ)-induced psoriasis-like mouse model. Spherical Cur-NPs with the mean particle sizes of 50nm and 150nm, respectively, were fabricated using a multi-inlet vortex mixer system, with both exhibiting significantly stronger anti-proliferation effect than Cur solution on HaCaT cells in vitro. Psoriatic skin was utilized in the in vitro skin penetration studies, and the results demonstrated that more drugs penetrated through or accumulated in the skin when administered as the Cur-NPs-loaded hydrogel compared to the drug suspension loaded hydrogel. To compare the nanosizing effect of these Cur-NPs, the mice with IMQ-induced psoriasis-like skin disease were treated with blank gel, Cur gel, 50nm sized NPs gel, 150nm sized NPs gel or tracrolimus cream (positive control), respectively. The results indicated that Cur-NPs hydrogel has a superior performance to Cur hydrogel on the IMQ-induced psoriasis-like mouse model in terms of morphological evaluation, biomarkers at mRNA, and protein levels. In conclusion, encapsulation of Cur into PLGA NPs, particularly for NPs of 50nm, could facilitate lipophilic Cur's dispersion, sustained-release, accumulation, and penetration across the skin and into the blood circulation, which significantly improves anti-psoriasis activity in mice.

Investigation of the luminescence, mechanical, and thermal properties of ZnO-entrapped poly(N-isopropyl acrylamide) gels

ZnO nanoparticles were synthesized in the pores that are formed inside the PNIPAm (poly(N-isopropyl acrylamide)) gels during polymerization. Different pore regions were obtained with changing the cross-linker concentrations of gels. We concluded from the SEM results that when the cross-linker concentration of the gels is increased, the average size of the pores becomes narrower. Thus, depending on the internal porosity of the gel, the size and distribution of ZnO nanoparticles were changed and accordingly it ranged in the fluorescence spectra. It is observed that fluorescence spectra of ZnO nanoparticles released from PNIPAm gel with low cross-linker concentration have only UV emission, while the nanoparticles released from PNIPAm gel with high cross-linker concentration have both the UV and the green emissions of ZnO. The size distributions of these nanoparticles were measured by Stabino-Nanoflex analyzer and it clearly indicates that the width of the size distribution decreases with increasing cross-linker concentration. To see the effect of ZnO nanoparticles on the properties of the gel, we investigated the luminescence, mechanical, and thermal properties of these ZnO/PNIPAm composites and plain gels of which the internal morphology was set by changing the cross-linker concentration. The nature of interactions between the nanoparticles and polymer strands affects both mechanical and thermal behaviors. Compared to plain gels, entrapping ZnO nanoparticles into the gels cause an increased compressive elastic modulus and strength. We proved that ZnO nanoparticles improve considerably the mechanical properties of PNIPAm gels.