Supported Palladium Nanoparticles Synthesized by Living Plants as a Catalyst for Suzuki-Miyaura Reactions

The metal accumulating ability of plants has previously been used to capture metal contaminants from the environment; however, the full potential of this process is yet to be realized. Herein, the first use of living plants to recover palladium and produce catalytically active palladium nanoparticles is reported. This process eliminates the necessity for nanoparticle extraction from the plant and reduces the number of production steps compared to traditional catalyst palladium on carbon. These heterogeneous plant catalysts have demonstrated high catalytic activity in Suzuki coupling reactions between phenylboronic acid and a range of aryl halides containing iodo-, bromo- and chloro- moieties.     

Development of a chitosan-based nanoparticle formulation for delivery of a hydrophilic hexapeptide, dalargin

Nanoparticle based delivery systems can offer opportunities for targeting, controlled release, and enhanced stability of their drug, protein, or gene therapy payload. This study investigated the use of chitosan in combination with the ionic additives sulfobutyl-ether-7-beta-cyclodextrin (SB-CD) or SB-CD/dextran sulfate (SB-CD/DS) mixture in comparison with chitosan: DS in the formulation of nanoparticles incorporating the hexapeptide dalargin. The physical characteristics (particle size, zeta potential), entrapment and loading efficiency, and release of dalargin were quantified. It was demonstrated that anionic cyclodextrin, SB-CD, can be used in complex coacervation with chitosan, with and without the presence of DS, to form nanoparticles. The presence of SB-CD or DS in the nanoparticle formulation and the weight ratio of chitosan to anionic additive(s) influenced the physical properties of the nanoparticles and their ability to carry dalargin. In addition, the particle size of nanoparticles was also affected by the molecular weight of chitosan and DS. The use of either DS or SB-CD/DS mixture produced chitosan nanoparticles with small particle size, high dalargin entrapment efficiency, enhanced peptide stability, and sustained release characteristics.     

Direct force measurements between siRNA and chitosan molecules using force spectroscopy

Information on the interaction strength between small interfering RNA (siRNA) and chitosan can contribute to the understanding of the formation and stability of chitosan/siRNA nanoparticles used as siRNA delivery systems for gene silencing. In this study, we utilize atomic force microscopy to obtain force spectroscopy results of the interaction strengths between siRNA and chitosan measured in physiological phosphate buffered saline buffer at different pH. The force measurements revealed that the adhesive interactions decreased in force strength and force frequency as the pH was increased from 4.1 to 6.1, 7.4, and 9.5, exhibiting distinct multimodal distributions of the interaction forces between siRNA and chitosan molecules at acidic pH and only negligible adhesive forces were observed at neutral or high pH. The strong pH dependence of siRNA-chitosan interactions can provide a convincing rationale for siRNA/chitosan complex formation and nanoparticle stability under low acidic conditions. These findings demonstrate that the use of force spectroscopy for the adhesive force measurements allows an evaluation of the complexing ability between siRNA and chitosan that can be utilized to predict nanoparticle stability.     

Preparation of Silica Nanoparticles Through Microwave-assisted Acid-catalysis

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle diameters ranging from 30-250 nm by varying the reaction conditions. Through the selection of a microwave compatible solvent, silicic acid precursor, catalyst, and microwave irradiation time, these microwave-assisted methods were capable of overcoming the previously reported shortcomings associated with synthesis of silica nanoparticles using microwave reactors. The siloxane precursor was hydrolyzed using the acid catalyst, HCl. Acetone, a low-tan δ solvent, mediates the condensation reactions and has minimal interaction with the electromagnetic field. Condensation reactions begin when the silicic acid precursor couples with the microwave radiation, leading to silica nanoparticle sol formation. The silica nanoparticles were characterized by dynamic light scattering data and scanning electron microscopy, which show the materials'' morphology and size to be dependent on the reaction conditions. Microwave-assisted reactions produce silica nanoparticles with roughened textured surfaces that are atypical for silica sols produced by Stöber''s methods, which have smooth surfaces.     

载基因壳聚糖纳米粒的制备及免疫增强作用的初步研究

摘 要 目的: 制备壳聚糖载基因纳米粒,并对其体外转染效率及其在小鼠体内的免疫增强效果进行初步研究。方法: 以本课题组构建的口蹄疫DNA疫苗为模型药物,采用复凝聚法制备纳米粒;用透射电镜观察形态;用纳米粒度分析仪测定粒径、多分散度和zeta电位;凝胶阻滞分析测定基因在纳米粒中的位置;用体外基因转染实验评价纳米粒的转染活性。用载基因壳聚糖纳米粒免疫雌性Balb/c小鼠,检测免疫小鼠的细胞免疫和体液免疫水平。结果: 所制备的载基因纳米粒形态规则、大多成球形,平均粒径约为150nm,多分散度＜0.26,zeta电位约为21mV;凝胶分析结果表明质粒DNA与壳聚糖分子间可以通过电性结合作用而完全结合,基因几乎全部被包裹在纳米粒内部;体外基因转染实验表明壳聚糖作为一种新型的非病毒基因递送载体能够高效传递DNA进入BHK-21细胞,基因能够在该细胞中高效表达;小鼠免疫实验表明纳米粒不仅能诱导机体产生较高的细胞免疫水平,而且体液免疫水平也显著提高。结论: 壳聚糖纳米粒能将基因递送到细胞内并且能够表达,小鼠免疫实验显示其具有良好的免疫增强效果。     

Association of the physical and chemical properties and the cytotoxicity of metal oxide nanoparticles: metal ion release, adsorption ability and specific surface area

Association of cellular influences and physical and chemical properties were examined for 24 kinds of industrial metal oxide nanoparticles: ZnO, CuO, NiO, Sb(2)O(3), CoO, MoO(3), Y(2)O(3), MgO, Gd(2)O(3), SnO(2), WO(3), ZrO(2), Fe(2)O(3), TiO(2), CeO(2), Al(2)O(3), Bi(2)O(3), La(2)O(3), ITO, and cobalt blue pigments. We prepared a stable medium dispersion for each nanoparticle and examined the influence on cell viability and oxidative stress together with physical and chemical characterizations. ZnO, CuO, NiO, MgO, and WO(3) showed a large amount of metal ion release in the culture medium. The cellular influences of these soluble nanoparticles were larger than insoluble nanoparticles. TiO(2), SnO(2), and CeO(2) nanoparticles showed strong protein adsorption ability; however, cellular influences of these nanoparticles were small. The primary particle size and the specific surface area seemed unrelated to cellular influences. Cellular influences of metal oxide nanoparticles depended on the kind and concentrations of released metals in the solution. For insoluble nanoparticles, the adsorption property was involved in cellular influences. The primary particle size and specific surface area of metal oxide nanoparticles did not affect directly cellular influences. In conclusion the most important cytotoxic factor of metal oxide nanoparticles was metal ion release.     

Regioselective Sequential Modification of Chitosan via Azide-Alkyne Click Reaction: Synthesis,Characterization, and Antimicrobial Activity of Chitosan Derivatives and Nanoparticles

Recently, the attention of researchers has been drawn toward the synthesis of chitosan derivatives and their nanoparticles with enhanced antimicrobial activities. In this study, chitosan derivatives with different azides and alkyne groups were synthesized using click chemistry, and these were further transformed into nanoparticles by using the ionotropic gelation method. A series of chitosan derivatives was successfully synthesized by regioselective modification of chitosan via an azide-alkyne click reaction. The amino moieties of chitosan were protected during derivatization by pthaloylation and subsequently unblocked at the end to restore their functionality. Nanoparticles of synthesized derivatives were fabricated by ionic gelation to form complexes of polyanionic penta-sodium tripolyphosphate (TPP) and cationic chitosan derivatives. Particle size analysis showed that nanoparticle size ranged from 181.03 ± 12.73 nm to 236.50 ± 14.32 nm and had narrow polydispersity index and positive surface charge. The derivatives and corresponding nanoparticles were evaluated in vitro for antibacterial and antifungal activities against three gram-positive and gram-negative bacteria and three fungal strains, respectively. The minimum inhibitory concentration (MIC) of all derivatives ranged from 31.3 to 250 µg/mL for bacteria and 188 to1500 µg/mL for fungi and was lower than that of native chitosan. The nanoparticles with MIC ranging from 1.56 to 25 µg/mLfor bacteria and 94 to 750 µg/mL for fungi exhibited higher activity than the chitosan derivatives. Chitosan O-(1-methylbenzene) triazolyl carbamate and chitosan O-(1-methyl phenyl sulfide) triazolyl carbamate were the most active against the tested bacterial and fungal strains. The hemolytic assay on erythrocytes and cell viability test on two different cell lines (Chinese hamster lung fibroblast cells V79 and Human hepatic cell line WRL68) demonstrated the safety; suggesting that these derivatives could be used in future medical applications. Chitosan derivatives with triazole functionality, synthesized by Huisgen 1,3-dipolar cycloaddition, and their nanoparticles showed significant enhancement in antibacterial and antifungal activities in comparison to those associated with native, non-altered chitosan.     

Rheological properties of chitosan-tripolyphosphate complexes: From suspensions to microgels

Complex fluids formed by crosslinking of chitosan (CS, 330 kDa) with sodium tripolyphosphate (TPP) have been studied by dynamic light scattering (DLS), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and rheology. The effects of chitosan/TPP ratios, initial chitosan or TPP concentrations, and ultrasonication time on the chitosan-TPP complex formation have been investigated. It was found that the optimum condition for CS-TPP nanoparticle formation occurred at CS/TPP mass ratio of 3.75 and with 9 min sonication treatment (energy output 3.75 W/mL). At the same initial chitosan concentration, small particle sizes (i.e., particle size < 300 nm) resulted in the formation of CS-TPP nanoparticle suspensions, which showed a lower viscosity than pure chitosan solutions, and their viscosities increased as the CS-TPP nanoparticles sizes increased. Centrifugation of CS-TPP particles of larger particle sizes (i.e., 360-870 nm) at 11,000 × g caused the formation of CS-TPP microgels. Dynamic rheological studies indicated that both storage modulus (G′) and loss modulus (G″) increased with particle sizes. During centrifugation processing, strong centrifugal force surmounted the electrostatic repulsion between CS-TPP particles and caused particles to stick with each other to form CS-TPP microgels. The water contents of microgels negligibly depended on particle size, suggesting that the free volumes of microgels were not affected by particle size, therefore supporting our pseudo-hard sphere assumption for CS-TPP nanoparticles.     

Preparation of gold nanopowders and nanoparticles using chitosan suspensions

Simple methods for preparation of gold nanopowders and nanoparticles are reported. Gold/chitosan nanoparticles were prepared by using basic chitosan suspension as a dispersant and as a reductant. The resulting nanoparticles were processed by pyrolysis and thus obtain black gold nanopowder. The FESEM images indicate that most diameters of the nanopowder prepared were in the range of 50 and 200 nm. Hydrolysis is another quick decomposition method for chitosan. Acetic acid was adopted to implement the hydrolysis. The AEM images of the auberginic suspension show that the average gold nanoparticle diameter was less than 40 nm with good dispersion. Use of chitosan suspensions can produce gold nanopowder as well as gold nanoparticle without using toxic organic chemicals.     

Enhancement of Thermal Properties of Polyvinylpyrrolidone (PVP)-Coated Silver Nanoparticles by Using Plasmid DNA and their Localized Surface Plasmon Resonance (LSPR) Characteristics

In this paper, the enhancement of thermal properties of polymer-coated silver nanoparticles by the addition of plasmid DNA is described. Nanoparticles of noble metals such as gold and silver possess specific characteristics by virtue of their quantum size effects. Therefore, noble metal nanoparticles are used for chemical sensing and biosensing applications based on their localized surface plasmon resonance absorption that can be measured in the visible region. The polyvinylpyrrolidone (PVP)-coated noble metal nanoparticles, in particular, with high dispersion ability in water, offer several advantages for sensing applications. However, some difficulties are encountered in the use of these PVP-coated noble metal nanoparticles for sensing applications due to their poor thermal properties. To improve the thermal properties of PVP-coated noble metal nanoparticles, we found that the addition of plasmid DNA to PVP-coated silver nanoparticles enhances their thermal properties due to good thermal stability of DNA. The introduction of plasmid DNA into PVP-coated silver nanoparticle dispersion enhanced the thermal properties through the formation of a complex between the nanoparticles and plasmid DNA. Furthermore, other polymers such as proteins and polyethylene glycol did not enhance the thermal properties of PVP-coated silver nanoparticles. Thus, the PVP-coated silver nanoparticle–plasmid DNA complex with enhanced thermal properties has a great potential for use in medical and drug delivery applications.     

Quaternized chitosan (QCS)/poly (aspartic acid) nanoparticles as a protein drug-delivery system

The aim of this study was to generate a new type of nanoparticles made of quaternized chitosan (QCS) and poly (aspartic acid) and to evaluate their potential for the association and delivery of protein drugs. QCS and poly (aspartic acid) were processed to nanoparticles via the ionotropic gelation technique. The size, polydispersity, zeta potential, and morphology of the nanoparticles were characterized. Entrapment studies of the nanoparticles were conducted using bovine serum albumin (BSA) as a model protein. The effects of the pH value of nanoparticles with different QCS/poly (aspartic acid) ratios, QCS molecular weight (MW), poly (aspartic acid) concentration, and BSA concentration on the nanoparticle size, the nanoparticle yield, and BSA encapsulation were studied in detail. Suitably pH value of nanoparticles with different QCS/poly (aspartic acid) ratios, moderate QCS MW, optimal concentration ratio of poly (aspartic acid), and QCS favored more nanoparticles formed and higher BSA encapsulation efficiency. The release of BSA from nanoparticles was pH-dependent. Fast release occurred in 0.1 M phosphate buffer solution (PBS, pH 7.4), while the release was slow in 0.1 M HCl (pH 1.2). The results showed that the new QCS/poly (aspartic acid) nanoparticles have a promising potential in protein delivery system.     

Folate-conjugated iron oxide nanoparticles for solid tumor targeting as potential specific magnetic hyperthermia mediators: synthesis, physicochemical characterization, and in vitro experiments

New folate-conjugated superparamagnetic maghemite nanoparticles have been synthesized for the intracellular hyperthermia treatment of solid tumors. These ultradispersed nanosystems have been characterized for their physicochemical properties and tumor cell targeting ability, facilitated by surface modification with folic acid. Preliminary experiments of nanoparticles heating under the influence of an alternating magnetic field at 108 kHz have been also performed. The nanoparticle size, surface charge, and colloidal stability have been assessed in various conditions of ionic strength and pH. The ability of these folate "decorated" maghemite nanoparticles to recognize the folate receptor has been investigated both by surface plasmon resonance and in folate receptor expressing cell lines, using radiolabeled folic acid in competitive binding experiments. The specificity of nanoparticle cellular uptake has been further investigated by transmission electron microscopy after incubation of these nanoparticles in the presence of three cell lines with differing folate receptor expression levels. Qualitative and quantitative determinations of both folate nanoparticles and nontargeted control nanoparticles demonstrated a specific cell internalization of the folate superparamagnetic nanoparticles.     

Preparation, characterization and transfection efficacy of chitosan nanoparticles containing the intestinal trefoil factor gene

Intestinal trefoil factor (ITF) is a novel polypeptide with potential pharmacological value for the prevention and healing of tissue injury; however, poor production capacity limits its clinical application. Chitosan, as a non-viral vehicle, has been successfully used in gene delivery for its intrinsic characteristics. In this context, we prepared chitosan nanoparticles enwrapping ITF cDNA and investigated its size, zeta potential, stability, release profiles, loading efficiency and loading capacity. Gene transfer capability was assessed in HEK293 cells. The data revealed that the chitosan/DNA nanoparticles were successfully prepared with sizes less than 500 nm and positive zeta potentials. The nanoparticles could protect DNA from nuclease degradation, and release profiles of DNA were dependent on N/P ratios. In addition, transfection efficiency of chitosan/DNA nanoparticles was equivalent to Lipofectamine (TM). Collectively, the results suggest that chitosan/DNA nanoparticles could be a promising method for ITF gene therapy.     

Generation of Zerovalent Metal Core Nanoparticles Using n-(2-aminoethyl)-3-aminosilanetriol

In this work, a facile one-pot reaction for the formation of metal nanoparticles in a water solution through the use of n-(2-aminoethyl)-3-aminosilanetriol is presented. This compound can be used to effectively reduce and complex metal salts into metal core nanoparticles coated with the compound. By controlling the concentrations of salt and silane one is able to control reaction rates, particle size, and nanoparticle coating. The effects of these changes were characterized through transmission electron microscopy (TEM), UV-Vis spectrometry (UV-Vis), Nuclear Magnetic Resonance spectroscopy (NMR) and Fourier Transform Infrared spectroscopy (FTIR). A unique aspect to this reaction is that usually silanes hydrolyze and cross-link in water; however, in this system the silane is water-soluble and stable. It is known that silicon and amino moieties can form complexes with metal salts. The silicon is known to extend its coordination sphere to form penta- or hexa-coordinated species. Furthermore, the silanol group can undergo hydrolysis to form a Si-O-Si silica network, thereby transforming the metal nanoparticles into a functionalized nanocomposites.     

Chitosan as an active support for assembly of metal nanoparticles and application of the resultant bioconjugates in catalysis

Metal nanoparticle-chitosan (NPs-chitosan) bioconjugates were formed by exposure of chitosan to an aqueous solution of metal salts under thermal treatment. The metal nanoparticles that are formed strongly bound to chitosan, which encouraged us to investigate their catalytic performance. It was demonstrated that the metal NPs-chitosan bioconjugates functioned as effective catalysts for the reduction of 4-nitrophenol in the presence of NaBH₄, which was monitored by means of spectrophotometry as a function of reaction time. The silver NPs-chitosan bioconjugates exhibited excellent catalytic activity and were reusable for up to seven cycles. In contrast, the gold NPs-chitosan catalyst displayed poor catalytic activity, even in the second cycle. A highlight of our approach is that chitosan simultaneously acts as an active support for the synthesis and assembly of nanoparticles, and the resultant bioconjugates bear the advantage of easy separation from the reaction medium.     

Green synthesis,characterization and biological activity of Solanum trilobatum-mediated silver nanoparticles

Biologically inspired synthesis of nanoparticles was found to be more attractive in metal nanoparticle synthesis. The present study reported an in-situ biogenic synthesis of silver nanoparticles (AgNPs) using Solanum trilobatum aqueous leaf extract. On this basis, the aqueous leaf extract of S. trilobatum acted as a reducing agent and stabilizing agent to synthesize highly stable AgNPs at ambient temperature. Eventually, the synthesized and stabilized AgNPs surface plasmon resonance was near 430 nm through a UV–visible (UV–vis) spectrophotometer. Here, the stability of the silver colloids monitored through zeta potential and mean particle size was evaluated through diffraction light scattering (DLF). Further, the average particle size was found to be 27.6 nm and spherical, confirmed with transmission electron microscopy (TEM). Also, colloidal AgNPs and aqueous extract are found to be rich sources of antioxidants and exhibit higher free radical scavenging ability. Thus, efficient inhibition with COX1 and COX2 enzymes and the protective effect with human red blood cell (HRBC) membrane stability showed significant results. These features are promising, suggesting the possibility of the AgNPs to be useful to disease-modifying for treating inflammatory disorders and associated complications.     

Developing a highly stable PLGA-mPEG nanoparticle loaded with cisplatin for chemotherapy of ovarian cancer

Background

Cisplatin is a potent anticancer drug, but its clinical application has been limited due to its undesirable physicochemical characteristics and severe side effects. Better drug formulations for cisplatin are highly desired.

Methodology/Principal Findings

Herein, we have developed a nanoparticle formulation for cisplatin with high encapsulation efficiency and reduced toxicity by using cisplatin-crosslinked carboxymethyl cellulose (CMC) core nanoparticles made from poly(lactide-co-glycolide)-monomethoxy-poly(polyethylene glycol) copolymers (PLGA-mPEG). The nanoparticles have an average diameter of approximately 80 nm measured by transmission electron microscope (TEM). The encapsulation efficiency of cisplatin in the nanoparticles is up to 72%. Meanwhile, we have also observed a controlled release of cisplatin in a sustained manner and dose-dependent treatment efficacy of cisplatin-loaded nanoparticles against IGROV1-CP cells. Moreover, the median lethal dose (LD₅₀) of the cisplatin-loaded nanoparticles was more than 100 mg/kg by intravenous administration, which was much higher than that of free cisplatin.

Conclusion

This developed cisplatin-loaded nanoparticle is a promising formulation for the delivery of cisplatin, which will be an effective therapeutic regimen of ovarian cancer without severe side effects and cumulative toxicity.     

Chitosan-Graft-Polyethylenimine/DNA Nanoparticles as Novel Non-Viral Gene Delivery Vectors Targeting Osteoarthritis

The development of safe and efficient gene carriers is the key to the clinical success of gene therapy. The present study was designed to develop and evaluate the chitosan-graft-polyethylenimine (CP)/DNA nanoparticles as novel non-viral gene vectors for gene therapy of osteoarthritis. The CP/DNA nanoparticles were produced through a complex coacervation of the cationic polymers with pEGFP after grafting chitosan (CS) with a low molecular weight (Mw) PEI (Mw = 1.8 kDa). Particle size and zeta potential were related to the weight ratio of CP:DNA, where decreases in nanoparticle size and increases in surface charge were observed as CP content increased. The buffering capacity of CP was significantly greater than that of CS. The transfection efficiency of CP/DNA nanoparticles was similar with that of the Lipofectamine™ 2000, and significantly higher than that of CS/DNA and PEI (25 kDa)/DNA nanoparticles. The transfection efficiency of the CP/DNA nanoparticles was dependent on the weight ratio of CP:DNA (w/w). The average cell viability after the treatment with CP/DNA nanoparticles was over 90% in both chondrocytes and synoviocytes, which was much higher than that of PEI (25 kDa)/DNA nanoparticles. The CP copolymers efficiently carried the pDNA inside chondrocytes and synoviocytes, and the pDNA was detected entering into nucleus. These results suggest that CP/DNA nanoparticles with improved transfection efficiency and low cytotoxicity might be a safe and efficient non-viral vector for gene delivery to both chondrocytes and synoviocytes.     

Correlated Optical Spectroscopy and Electron Microscopy Studies of the Slow Ostwald-Ripening Growth of Silver Nanoparticles under Controlled Reducing Conditions

Metallic nanoparticles display distinct localized surface plasmon resonance (LSPR) properties that depend on their size, shape, and composition and that can be monitored to characterize their growth. Utilizing LSPR properties, we report the first investigation of ambient temperature formation of trioctylamine (TOA)-stabilized spherical silver nanoparticles (AgNPs) of ～3.0-nm diameter by mild reduction of AgClO₄ with the weak reducing agent heptamethyltrisiloxane in organic solvent. The appropriate choice of experimental conditions caused slow reduction, which allowed the study of the nanoparticle growth process by time-resolved UV–visible spectroscopy and transmission electron microscopy (TEM). The linear nanoparticle growth kinetics from 50 min to end of the reaction derived from LSPR changes, the absence of a bimodal size distribution during the initial stage of the reduction process from TEM analysis, and the single crystallinity of the resulting AgNPs suggested a diffusion-controlled Ostwald-ripening growth process. It was also found that in addition to its stabilizing ability, TOA acted as a catalyst and facilitated Ag⁺ reduction. Furthermore, a modest increase in reaction temperature caused a substantial enhancement in the AgNP formation rate, and low concentration of stabilizing ligand yielded an increase in size and dispersity.     

Photoinduced Disaggregation of TiO2 Nanoparticles Enables Transdermal Penetration

Under many aqueous conditions, metal oxide nanoparticles attract other nanoparticles and grow into fractal aggregates as the result of a balance between electrostatic and Van Der Waals interactions. Although particle coagulation has been studied for over a century, the effect of light on the state of aggregation is not well understood. Since nanoparticle mobility and toxicity have been shown to be a function of aggregate size, and generally increase as size decreases, photo-induced disaggregation may have significant effects. We show that ambient light and other light sources can partially disaggregate nanoparticles from the aggregates and increase the dermal transport of nanoparticles, such that small nanoparticle clusters can readily diffuse into and through the dermal profile, likely via the interstitial spaces. The discovery of photoinduced disaggregation presents a new phenomenon that has not been previously reported or considered in coagulation theory or transdermal toxicological paradigms. Our results show that after just a few minutes of light, the hydrodynamic diameter of TiO₂ aggregates is reduced from ∼280 nm to ∼230 nm. We exposed pigskin to the nanoparticle suspension and found 200 mg kg⁻¹ of TiO₂ for skin that was exposed to nanoparticles in the presence of natural sunlight and only 75 mg kg⁻¹ for skin exposed to dark conditions, indicating the influence of light on NP penetration. These results suggest that photoinduced disaggregation may have important health implications.