Polyvinyl Chloride Surfaces Research Articles

Grafted copolymerization of N-phenylmaleimide and styrene in porous polyvinyl chloride particles suspended in aqueous solution

ABSTRACTN-phenylmaleimide (N-PMI) and its precursor, (Z)-4-oxo-4-(phenylamino)but-2-enoic acid, were synthesized from aniline and maleic anhydride. Copolymerization between N-phenylmaleimide and styrene was initiated in micropores and outside surface of porous polyvinyl chloride (PVC) resin suspended in aqueous phase. The modified PVC was characterized with Gel Permeation Chromatography, thermal gravimetric analysis and scanning electron microscopy. The result of high performance liquid chromatography shows that the purity of N-PMI reached 97.3%. Thermal gravimetric analysis indicated that the introduction of N-PMI could clearly affect the thermal degradation behavior of PVC, and when PMI was at 6.25% of the PVC mass, the decomposition temperature T0.5 of modified polymer was increased to 314.2°C. The glass transition temperature of modified polymer was increased from 70°C to 80°C.

A rapid one-step surface functionalization of polyvinyl chloride by combining click sulfur(vi)-fluoride exchange with benzophenone photochemistry.

Polyvinyl chloride (PVC) is an important biomedical material, but there is a lack of convenient functionalization methods. Here, a rapid, effective and simple one-step strategy for PVC surface functionalization by combining the "sulfur(vi)-fluoride exchange" (SuFEx) reaction with benzophenone photochemistry is presented.

Analysis the Surface Morphology of the Porous Media by using Atomic Force Microscope technique

An atomic force microscope (AFM) technique is utilized to investigate the polystyrene (PS) impact upon the morphological properties of the outer as well as inner surface of poly vinyl chloride (PVC) porous fibers. Noticeable a new shape of the nodules at the outer and inner surfaces, namely "Crater nodules", has been observed. The fibers surface images have seen to be regular nodular texture at the skin of the inner and outer surfaces at low PS content. At PS content of 6 wt.%, the nodules structure was varied from Crater shape to stripe. While with increasing of PS content, the pore density reduces as a result of increasing the size of the pore at the fiber surface. Moreover, the test of 3D-AFM images shows that the roughness of both surfaces of fibers seems to be decreased with PS content. Alternatively, the fibers pure water permeability (PWP) has been declined with decreasing of fiber roughness.

Overshadow Effect of Psl on Bacterial Response to Physiochemically Distinct Surfaces Through Motility-Based Characterization.

Biofilms of Pseudomonas aeruginosa are ubiquitously found on surfaces of many medical devices, which are the major cause of hospital-acquired infections. A large amount of work has been focused on bacterial attachment on surfaces. However, how bacterial cells evolve on surfaces after their attachment is the key to get better understanding and further control of biofilm formation. In this work, by employing both single-cell- and collective-motility of cells, we characterized the bacterial surface movement on physiochemically distinct surfaces. The measurement of cell surface motility showed consistent results that gold and especially platinum surfaces displayed a stronger capability in microcolony formation than polyvinyl chloride and polycarbonate surfaces. More interestingly, we found that overproduction of Psl led to a narrower variance in cell surface motility among tested surfaces, indicating an overshadow effect of Psl for bacteria by screening the influence of physicochemical properties of solid surfaces. Our results provide insights into how Pseudomonas aeruginosa cells adapt their motion to physiochemically distinct surfaces, and thus would be beneficial for developing new anti-biofouling techniques in biomedical engineering.

Eliminating the Need for Biocidal Agents in Anti-Biofouling Polymers by Applying Grafted Nanosilica Instead.

A nondestructive one-step approach was applied for grafting biocide-free monodispersed silica nanoparticles (SNPs) with a diameter of 30 ± 10 nm on polystyrene, polyethylene, and polyvinyl chloride surfaces. The prepared surfaces were comprehensively characterized using spectroscopic (Fourier transform infrared attenuated total reflection, ultraviolet–visible, and X-ray photoelectron spectroscopy) and microscopic (high-resolution scanning electron microscopy and atomic force microscopy) methods. The modified polymers were found to maintain their original mechanical and physical properties, while their nanoroughness on the other hand had risen by 1.6–2.7 times because of SNP grafting. The SNP-grafted surfaces displayed anti-biofouling properties, resulting in a significant reduction in the attached Gram-positive Bacillus licheniformis or Gram-negative Pseudomonas aeruginosa bacteria compared to their nongrafted counterparts. Confocal laser scanning microscopy and scanning electron microscopy studies have confirmed that bacterial cells could not successfully adhere onto the SNP-grafted polymer films regardless of the polymer type, and their biofilm formation was therefore damaged. The presented facile and straightforward protocol allows eliminating the need for biocidal agents and resorts to grafted nanosilica instead. This strategy may serve as a feasible and safe platform for the development of sustainable anti-biofouling surfaces in biomedical devices; food, water, and air treatment systems; and industrial equipment.

A novel amperometric bienzymatic biosensor based on alcohol oxidase coupled PVC reaction cell and nanomaterials modified working electrode for rapid quantification of alcohol

A new amperometric sensor has been fabricated for sensitive and rapid quantification of ethanol. The biosensor assembly was prepared by covalently immobilizing alcohol oxidase (AOX) from Pichia pastoris onto chemically modified surface of polyvinylchloride (PVC) beaker with glutaraldehyde as a coupling agent followed by immobilization of horseradish peroxidase (HRP), silver nanoparticles (AgNPs), chitosan (CHIT), carboxylated multi-walled carbon nanotubes (c-MWCNTs) and nafion (Nf) nanocomposite onto the surface of Au electrode (working electrode). Owing to properties such as chemical inertness, light weight, weather resistance, corrosion resistance, toughness and cost-effectiveness, PVC membrane has attracted a growing interest as a support for enzyme immobilization in the development of biosensors. The amperometric biosensor displayed optimum response within 8 s at pH 7.5 and 35°C temperature. A linear response to alcohol in the range of 0.01mM–50 mM and 0.0001 µM as a minimum limit of detection was displayed by the proposed biosensor with excellent storage stability (190 days) at 4°C. The sensitivity of the sensor was found to be 155 µA mM−1 cm−2. A good correlation (R2 = 0.99) was found between alcohol level in commercial samples as evaluated by standard ethanol assay kit and the current biosensor which validates its performance.

Optical fiber based soft curvature sensor with polyvinyl chloride reinforced silicone rubber substrate

To meet the demands for curvature measurement in the field of biomedical intelligent equipment, soft robots and complex structures of major infrastructures, an optical fiber based soft curvature sensor is proposed. The major contribution is obtaining a soft curvature sensor with extraordinary high sensitivity and repeatability. A silicone rubber sheet is glued on the surface of polyvinyl chloride to form polyvinyl chloride (PVC) reinforced silicone rubber substrate, the fiber Bragg grating is embedded into the substrate to form the sensor. The sensor is calibrated using standard curvature calibration blocks. The characteristic of the reflected spectrum of the sensor is analyzed. The relation between the sensitivity and the fiber embedded depth is obtained. The research results prove that the real-time measurement of structure curvature can be realized by the sensor. The polyvinyl chloride reinforced silicone rubber substrate is helpful to improve the sensitivity and repeatability of the sensor. The maximum sensitivity is up to 329.2pm/m−1. The sensor has good consistency in repeated measurements, it has application presents in measuring the curvature of flexible mechanisms and complex structures.

Immunomagnetic separation combined with RT-qPCR for evaluating the effect of disinfectant treatments against norovirus on food contact surfaces

Despite the importance of preventing the spread of human norovirus (NoV), effective disinfectants are lacking. In this study, the efficacy of disinfectants against NoV on various non-porous surfaces was investigated by immunomagnetic separation (IMS) and quantitative real-time reverse transcription (RT-q)PCR. Monoclonal anti-NoV antibody-conjugated magnetic beads captured intact viral particles for RT-qPCR after the treatment of surfaces with disinfectants. Viral suspensions of approximately 5.97 log10 genomic copies were inoculated onto rubber, glass, stainless steel, ceramic tile, wood, and polyvinyl chloride surfaces. Various elution buffers were used to elute NoV from surfaces. Ethanol (50–70%), sodium hypochlorite (NaOCl, 100–1000 ppm), sodium metasilicate (SMS, 0.1% and 0.3%), and quaternary compounds (1000–2000 ppm) were investigated as disinfectants; the observed reductions were <1 log10, except for SMS (1.17 ± 0.21 to 2.71 ± 0.06 log10 reduction) and 700–1000 ppm NaOCl (1.04 ± 0.07 to 2.03 ± 0.05 log10 reduction). Ethanol and quaternary compounds exhibited low efficacy against NoV GII.4 on all surfaces. These results indicated that SMS is the most effective disinfectant and emphasized the need to develop suitable agents to inactivate NoV on surfaces.

Textural, surface and chemical properties of polyvinyl chloride particles degraded in a simulated environment

Virgin polyvinyl chloride (PVC) particles were exposed to heat, ultraviolet B (UVB) and solar radiation either in artificial seawater or in air for different periods of time. The surface and chemical properties of fresh and degraded particle surfaces were determined via image analysis using scanning electron micrographs, a Brunauer-Emmett-Teller (BET) specific surface area analyzer and infrared spectroscopy. Thermal and UVB degradation resulted in unique PVC morphologies. In addition, the increased presences of functional groups were evident as dehydrochlorination and oxidation during the degradation process, which altered the chemical properties of PVC. In contrast, under solar exposure with or without seawater, unevenness to the surface was noted that seems to originate from degradation of the PVC surface; in addition, no new functional groups were found. This suggests that the chemical properties of PVC are stable over extended periods in the marine environment.

The effects of poly(amide-imide) coating on the thermal, combustion and mechanical properties of polyvinyl chloride ZnO nanocomposites

The surface of new polyvinyl chloride (PVC)/ZnO nanocomposite films was coated using semi-aromatic synthesized poly(amide-imide) (PAI) by dip-coating process. ZnO nanoparticles were organo-modified with imide functionalized polyethyleneimine (PEI) and were used for preparation of PVC nanocomposite films by solution casting method. The effect of PAI coating along with PEI surface modified ZnO nanoparticles (PSZN) on the morphology, thermal stability, combustion and mechanical properties of PVC were investigated. The uniform dispersion of ZnO nanoparticles and PAI coating manner on surface of the PVC films were confirmed by ATR-FTIR spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray and elemental mapping. From thermal gravimetry analysis (TGA) results, the 10 mass% loss temperature (T10) increased from 229 °C to 244 °C in PVC-coated with PAI containing 2 mass% of PSZN and also char residue of PVC increase from 10.5 to 28.9% in PVC-coated contaning 5 mass% of PSZN. According to microscale combustion calorimetry (MCC) and tensile test results, the peak of heat release rate decreased from 129.8 W/g to 81.2 W/g and the tensile strength increased from 28.7 to 43.6 MPa for PVC-coated containing 5 mass% of PSZN compared to the neat PVC.

Laser assisted joining of AA5053 aluminum alloy with polyvinyl chloride (PVC)

Laser Assisted Joining (LAJ) of Aluminum AA5053 sheets with Polyvinyl chloride (PVC) is investigated. The process was performed by means of a diode laser with a maximum power of 200 W. The materials did not show good chemical affinity. Thus, laser sculpturing was performed on the aluminum substrate before joining. This enabled to produce teeth features on the aluminum surface. Thus, the main joining mechanism was based on the penetration of the teeth throughout in PVC surface. The influence of the scanning speed and laser beam power used during the LAJ process on the mechanical strength of the joints was investigated. Single lap shear tests were conducted. Morphological analysis was carried out by means of optical microscopy. Thermal analysis was also conducted to measure the thermal field and the thermal history of the specimen during LAJ process. The results indicated the presence of two opposite phenomena: poor penetration of the teeth (due to insufficient heating) and polymer degradation (due to excessive heating). Both these conditions affected severely the mechanical strength of the joints. Great variation of the temperature and the morphology was observed on the joints. Under optimal conditions (P = 200 W and Ss = 100 mm/min), the average joint strength reached 71% (15.3 MPa) of the base material shear strength.

Studying the effect of concentration factors on the process of chemical metallization of powdered polyvinylchloride

Influence of concentration of components of chemical metallization solutions on the process of copper reduction on activated polyvinylchloride surface has been studied. It has been established that changes in concentrations of copper sulfate, trilon B and formaldehyde can effectively influence the metallization process. It was shown that the loss of stability of chemical metallization solutions and formation of colloidal solutions makes it is impossible to obtain a metallized polymeric material since copper reduction occurs in the solution volume. Copper reduction in the solution volume occurs because of presence of insoluble colloidal particles of copper hydroxide which are centers of nucleation of copper reduction. At such centers, copper reduction occurs as a result of reaction with formaldehyde and is accompanied by high volumes of hydrogen evolvement. It has been established that the formation of copper coating on an activated polymer surface occurs only with the use of true chemical metallization solutions. The main factor determining stability of chemical metallization solutions is complexing. It was shown that trilon B concentration under 40 mmol/l is not sufficient to bind all Cu 2+ ions in a complex which prevents formation of insoluble copper hydroxide in an alkaline medium. The growth of trilon B concentration above 53 mmol/l results in reduction of a portion of copper in a form of hydroxide and formation of true solutions. It has been established that concentration of copper sulfate and alkali exerts the main influence on the mechanism of copper reduction in the case of true solutions. The growth of pH of chemical metallization solutions above 12 brings about an increase in the portion of copper that is reduced by the exchange reaction with zinc.

Method Modification for the Atlas Listeria Environmental LE Detection Assay Using FoodChek Actero Listeria Enrichment Media and Half-Fraser Media for the Detection of Listeria spp. from Environmental Surfaces

Two candidate method modifications for the Atlas Listeria Environmental LE Detection Assay were compared with the U.S. Department of Agriculture (USDA)-Food Safety and Inspection Service Microbiology Laboratory Guidebook 8.09 (MLG 8.09) method for detection of Listeria spp. on stainless steel, polyvinyl chloride (PVC), and sealed concrete surfaces. For LE candidate method 1, samples were enriched in FoodChek Actero Listeria Enrichment Media [ALEM; Performance Tested MethodSM (PTM) 111201] at 35 ± 2°C for 18 to 24 h and evaluated for a range of analytical sample volumes. For LE candidate method 2, the current Roka PTM using 90 mL of Half-Fraser broth for enrichment at 35 ± 2°C was evaluated at 24 h with a reduced sample volume. These comparisons were made in multiple studies across the three environmental surfaces. Within each method and study, a total of 5 samples were uninoculated, 20 samples were inoculated with Listeria spp. at a low level to target fractional positivity, and 5 samples were inoculated with Listeria spp. at a high level to approach a probability of detection of 1. Inclusivity and exclusivity studies were also conducted for the LE method in combination with Half-Fraser and ALEM. The Atlas Listeria Environmental LE Detection Assay detected all 50 inclusive organisms, including 25 strains of L. monocytogenes and 5 strains of each of the other five common species of Listeria (L. innocua, L. welshimeri, L. ivanovii, L. seeligeri, and L. grayi) and none of the 30 exclusive organisms across all media and with both 200 and 2000 µL sample volumes. For the LE candidate method 1 studies, no significant differences were observed within the Roka ALEM method at 18, 20, or 24 h and for both the 200 and 2000 µL sample volumes as compared with the paired culture outcome. However, the ALEM method performed significantly better as compared with the unpaired reference method for sealed concrete and stainless steel. For the LE candidate method 2 studies, no significant differences were observed within the Roka HF method at 24 h for the 200 and 2000 µL samples as compared with the paired culture outcomes and unpaired reference method outcomes across the surfaces. The independent laboratory studies observed no significant differences in performance between the USDA/MLG 8.09 reference method and candidate methods 1 or 2, respectively, across the evaluated parameters. Overall, the candidate method 1 modification parameters and candidate method 2 sample parameters for the Atlas Listeria Environmental LE Detection Assay were statistically equivalent to or better than the reference method for detection of Listeria spp. on stainless steel, PVC, and sealed concrete surfaces, providing greater flexibility in method application for end users.

Inhibition and removal of staphylococcal biofilms using Moringa oleifera Lam. aqueous and saline extracts

Staphylococcus spp., especially Staphylococcus aureus, are prevalent in milk production and one of the major bacterial agents causing foodborne diseases in Brazil, with a health risk to consumers. During milk processing, the concomitant production of effluents can deliver these microorganisms to the environment, and later to the basic sewage network. Bacterial biofilms in dairy industries have often been associated with the contamination of dairy products. Natural antibacterial agents, including Moringa oleifera Lam., have been used as an alternative to the chemicals methods, which exhibits activity against some pathogens. The aim of this study was to investigate the activity of the extract from M. oleifera seeds against the biofilm formation by Staphylococcus spp. isolated from the effluents of a dairy industry (Paraná-Brazil). The results showed that 20% S. aureus isolates and 66.7% coagulase negative Staphylococcus (CNS) isolates presented resistance to the drugs tested. The aqueous and the saline extracts of M. oleifera reduced approximately 2 log CFU/cm2 of the isolates on the stainless steel and polyvinyl chloride (PVC) surfaces. Scanning electron microscopy images revealed changes after the application of the extracts in the biofilms, revealing the effectiveness of M. oleifera for the removal of bacterial biofilms.

Bio-inspired superhydrophilic coatings with high anti-adhesion against mineral scales

The unexpected adhesion of certain inorganic minerals on solid surfaces is constantly a source of severe problems in daily life and industrial production, including scales in water pipes. Inspired by the nanostructured inner surface of normal renal tubules, we design a superhydrophilic nanohair coating composed of a poly(hydroxyethyl methacrylate) (PHEMA) hydrogel, which shows high anti-adhesion against mineral scales under flow conditions. Even at a high temperature of 80° C, the nanohair hydrogel coatings still show excellent anti-scaling performance compared to a flat hydrogel coating and a commercial water pipe with a polyvinylchloride (PVC) surface. The anti-scaling experiments and theory simulation reveal the crucial role of superhydrophilicity and fluid-assisted motion of the nanohairs in the anti-adhesion property. This study may provide promising insight into the design of high anti-adhesion coatings for resisting mineral scale attachment in water management systems.

Separation of polyvinylchloride (PVC), polystyrene (PS) and polyethylene terephthalate (PET) granules using various chemical agents by flotation technique

Abstract A mixture of traditional virgin (unused) plastics ordinarily available in municipal wastes, polyvinylchloride (PVC), polystyrene (PS) and polyethylene terephthalate (PET) was treated with several chemical agents, i.e., polyvinyl alcohol (PVA), polyethylene glycol (PEG), methyl cellulose (MC), tannic acid (TA) and methyl isobutyl carbinol (MIBC), individually or combine with each other. The effects of various parameters on the floatability of the used plastics, namely, chemical agent type and concentration, conditioning temperature and time and liquid media pH, were studied and the results were discussed. It revealed that in most experiments, the PET sustained the least flotation change for the studied chemical agents and was sunk at the bottom of the flotation tank. The TA was useful on the PVC flotation through surface adsorption and changing the PVC surface hydrophobic behavior in different ways depending on the TA concentration. With the PET exception, the increasing temperature improved floatability of the studied plastics for used chemical agents. The raising the pH of the liquid media changed the floatability of the studied plastics in different ways depending on the pH value and the used chemical agent. In most cases, the increasing conditioning time was beneficial to the plastic flotation up to 15 min. As an essential conclusion, the PVC and PS could be separated from PET in their mixture by using TA-PEG with 0.2–0.8 ratio and TA-PEG with equal ratio plus 2 ml/L MIBC in two stages completely. The comparison of the results with other studies showed the shape and size of the used plastics were crucial factors on the separation of the studied plastics by the flotation technique.

Bacteriophage use to control Salmonella biofilm on surfaces present in chicken slaughterhouses

Foodborne diseases represent a major risk to public health worldwide. Pathogenic bacteria can live in the form of biofilm within the food industry, providing a permanent source of contamination. The aim of this study was to evaluate the influence of the types of adhesion surfaces on Salmonella biofilm formation at eight different times, and analyze the action time of a bacteriophage pool on established biofilms. Most of the samples used were classified as weak biofilm producers, with serovars Enteritidis and Heidelberg showing the highest frequency of biofilm formation. Glass and stainless steel surfaces significantly favored biofilm formation at 60 and 36 h of incubation respectively, but the polyvinyl chloride surface did not favor biofilm production, suggesting that the type of material may interfere with production. The bacteriophage pool action period focused on 3 h, but treatment of 9 h on glass surface biofilms was superior to other treatments because it affected the largest number of samples. These results suggests that some surface types and Salmonella serotypes may promote biofilm formation and indicate bacteriophages as an alternative to control biofilms. But further studies are required to prove the effectiveness and safety of bacteriophage therapy as an alternative in the antimicrobial control in the processing plants.

Effect of chlorine treatment on inhibition of E. coli serogroup O2 incorporation into 7-day-old biofilm on polyvinylchloride surface

Poultry waterlines are constructed using polyvinylchloride (PVC) material on which bacterial biofilm can easily form. Biofilm can harbor pathogens including avian pathogenic E. coli (APEC) strains. An in vitro evaluation was performed to determine if E. coli sero group O2 (avian pathogenic) could attach on a PVC surface that had pre-formed biofilm and if this phenomenon could be affected when water was treated with chlorine. Initially, biofilm growth was induced in PVC test coupons (15.16 cm2) for a 7-day period mimicking the waterline scenario in the first wk of poultry brooding; and then this biofilm was challenged with E. coli O2 seeded water in presence/absence of chlorine treatment. After rinsing, test coupons were sampled for bacterial (APC) and E. coli O2 enumeration at various occasions post seeding the pathogen and chlorine treatment. Day 7 APC recovered from coupons was 4.35 log10 cfu/cm2 in trial 1 and 3.66 log10 cfu/cm2 in trial 2. E. coli O2 was not recovered from chlorine treated test coupons (P <0.05), whereas it was retrieved from untreated coupons (untreated contained >3 log10 cfu/cm2 in trial 1 and >2 log10 cfu/cm2 in trial 2). This study suggests that E. coli O2 can incorporate into pre-formed biofilm on a PVC surface within 24 h if water sanitation is not present, and the attachment time of the pathogen can prolong in the absence of already formed biofilm.

Optical and thermogravimetric analysis of Pb3O4/PVC nanocomposites

Pb3O4 nanoparticles were embedded in a Polyvinyl chloride (PVC) polymer matrix with different filler ratios 0, 1, 2, 3 and 4 wt%. The nanocomposite films are prepared at room temperature via solution-casting technique. XRD analysis showed that pure PVC film is partially crystalline and Pb3O4 nanoparticles have a tetragonal crystal structure. TEM revealed nearly spherical Pb3O4 nanoparticles with average size around 24.3 nm which is very close to that obtained from XRD. Scanning electron microscopy micrographs indicated a PVC film with uniform surface morphology and Pb3O4 nanoparticles are well dispersed on the PVC surface. The optical band gap, Eopt, values calculated from optical absorption spectra decreased from 5.05 to 4.34 eV with increasing Pb3O4 wt%. Also, both Fermi energy, EF, and Urbach energy, ∆E, increased with increasing Pb3O4 filler content. The addition of Pb3O4 nanoparticles increases the solar material protection factor (SMPF) from 99.89 to 99.99%. Thermogravimetric analysis revealed that Pb3O4/PVC nanocomposites have high thermal stability rather than pure PVC film.

Development of dry-origin latent footwear impression on non-porous and semi-porous surfaces using a 5-methylthioninhydrin and L-alanine complex

5-methylthioninhydrin (5-MTN) is an amino acid sensitive reagent used for the development of latent fingermarks deposited on porous surfaces such as paper and wood. The present study demonstrates that the 5-MTN can be used as a latent footwear impression enhancement reagent, by reacting with trace multivalent metal ions, which are the main components of the latent footwear impression. 5-MTN and L-alanine complex (MTN-ALA) used for the latent footwear impression development was prepared, by mixing 4.5×10 −3 M 5-MTN (in methanol) and 4.5×10 −3 M L-alanine (in methanol) in 1:1 ratio, and keeping undisturbed at room temperature for 24 h. The latent footwear impressions were deposited on white and black non-porous surfaces (glass plate, polyethylene panel, polypropylene panel, acryl panel, polyvinyl chloride (PVC) panel, poly(methyl methacrylate) (PMMA) panel, acrylonitrile-butadiene-styrene (ABS) panel, tile), and a semi-porous surfaces (painted wood). The latent footwear impressions on these surfaces were treated with MTN-ALA complex by spraying. The fluorescence of footwear impressions (occurred due to the reaction between MTN-ALA and metal complexes) was observed under a 505 nm forensic light source and an orange barrier filter. The enhancement of latent footwear impression was achieved from black surfaces without any blurring. However, the fluorescence (enhancement) of footwear impression was not observed on the white PVC, PMMA, and ABS surfaces, because the incident light interfered and reflected on the surface. The sensitivity of MTN-ALA was superior to 2,2’-dipyridil, which is a representative non-fluorescing footwear impression enhancement reagent, and similar to 8-hydroxyquinoline, which is a representative fluorescing footwear impression enhancement reagent.