Laser-induced periodic structure and chemical composite coating synergetic antibacterial surface and preparation method thereof

Abstract

The invention discloses a laser-induced periodic structure and chemical composite coating synergetic antibacterial surface and a preparation method thereof. A periodic surface structure LIPSS is etched on the surface of a base material through laser treatment, the structure period is controlled to be about 350 nm, the surface subjected to laser treatment is combined with a composite chemical coating (PCA) through chemical plating, and polydopamine PDA serving as a strong adhesive can be combined with non-toxic natural polymer chitosan CS; meanwhile, silver ions Ag < + > are reduced into silver nanoparticles (AgNPs) by utilizing the reduction characteristic of PDA, PDA-CS-Ag is co-deposited on the LIPSS through chemical plating, the modified Ti-PCA-LIPSS modified surface is obtained, and the modified surface can remarkably inhibit biological film formation and reduce bacterial adhesiveness. The modification method can be applied to the field of material surfaces, and particularly has potential application prospects in modification of medical implant materials.

Description

Technical Field

[0001] The present invention relates to the technical field of material surface modification, and particularly relates to an antibacterial surface synergistically composed of laser-induced periodic structures and chemical composite coatings and a preparation method thereof. Background Art

[0002] The problems of bacterial colonization and biofilm infection on the surface of medical devices are becoming increasingly prominent. On the occasion of the advent of the "post-antibiotic era", traditional antibacterial means relying on antibiotics or antibacterial agents can no longer meet the clinical needs. In particular, the excessive use of drugs can cause cytotoxicity and accelerate the occurrence of complications such as inflammation. Especially with the emergence of the multi-drug resistance (MDR) of "super bacteria", the risk of infection is further increased. In addition, single surface modification technologies represented by constructing biomimetic surface topographies or chemical coatings have problems of insufficient antibacterial efficiency and persistence in solving the problem of bacterial attachment.

[0003] Constructing special surface topologies (such as biomimetic surfaces) has been verified to be effective in resisting bacterial adhesion and subsequent biofilm formation. Special texture surfaces constructed by various processing means such as lasers and plasmas limit the available sites for bacterial adhesion and at the same time have a mechanical bactericidal effect. LIPSS (Laser-Induced Periodic Surface Structures) is a micro-nano scale periodic structure formed on the surface of solid materials by laser processing. Since it was first discovered in 1965, LIPSS has become an important research object in the field of laser micro-nano manufacturing. The formation of LIPSS is the result of the interaction between the laser and the material. Its characteristics such as period and direction are closely related to the wavelength, pulse width, energy density, polarization direction of the laser and the properties of the material. LIPSS has broad application prospects in multiple fields, including: the optical field, materials science, biomedicine, the energy field, etc., and is widely used in various material modification fields.

[0004] In the field of coatings, mussel-inspired polydopamine (PDA) is regarded as a "promising" polymer for material surface modification by the scientific community due to its excellent adhesion and covalently modifiable groups. Natural polymers with high bactericidal efficiency (such as chitosan CS) have also attracted much attention because of their good biocompatibility and low cytotoxicity. In addition, silver nanoparticles (AgNP) are widely used in constructing antibacterial coatings due to their larger specific surface area and high-efficiency killing characteristics against Gram-positive bacteria and Gram-negative bacteria. However, this type of bactericidal coating based on the release mode is itself restricted by the amount of antibacterial agent that can be incorporated, thus limiting their long-term effectiveness.

[0005] In recent years, a hybrid synergistic antibacterial strategy combining morphological and chemical methods has attracted much attention as an attractive solution, aiming to break through the limitations of the single antibacterial mode of physical 'passive limitation' and chemical 'active sterilization'. These composite methods have the potential to significantly improve antibacterial efficiency and enhance long-term stability and biocompatibility. Summary of the Invention

[0006] The object of the present invention is to provide an antibacterial surface synergistically composed of laser-induced periodic structures and chemical composite coatings, so as to improve the bacterial adhesion on the surface of medical materials and enhance the antibacterial performance of the materials.

[0007] To achieve the above object, the present invention provides an antibacterial surface synergistically composed of laser-induced periodic structures and chemical composite coatings, which antibacterial surface comprises a PCA composite coating obtained by laser treatment and electroless plating.

[0008] Preferably, the periodic surface structure obtained by laser treatment of the above antibacterial surface is low spatial frequency LIPSS perpendicular to the light polarization direction, and its period is 350 nm.

[0009] Preferably, the PCA composite coating of the above antibacterial surface is a co-deposition comprising polydopamine PDA, chitosan CS, and silver nanoparticles AgNPs.

[0010] Preferably, the substrate of the above antibacterial surface is selected from metallic titanium, stainless steel, alloys, or medical implant materials, and can also be used for surface modification of ceramics, plastics, textiles, etc.

[0011] The present invention also provides a preparation method of an antibacterial surface synergistically composed of laser-induced periodic structures and chemical composite coatings, comprising the following steps:

[0012] S1: Laser-treat the substrate to be modified to obtain a LIPSS surface, and the period of the obtained LIPSS surface is 350 nm;

[0013] S2: Conduct electroless plating on the obtained LIPSS surface in an electroless plating solution to complete the co-deposition of polydopamine PDA and chitosan CS;

[0014] S3: Deposit silver nanoparticles AgNPs on the material obtained by electroless plating to obtain the antibacterial surface; wherein, the process parameters of the above LIPSS surface treatment include the following:

[0015]

[0016] Among them, the above electroless plating solution is prepared by mixing dopamine hydrochloride, chitosan CS, and ammonium persulfate AP with a final concentration of 2 g L -1 in an HCl solution with pH = 3.8.

[0017] Preferably, S1 of the above preparation method further includes ultrasonic cleaning of the substrate to be modified before laser treatment, and removal of the oxide layer after laser treatment.

[0018] Preferably, the electroless plating in the above preparation method S2 is soaking in an electroless plating solution at 60 °C for 24 hours.

[0019] Preferably, the deposition of silver nanoparticles AgNPs in the above preparation method S3 is soaking in a 0.01M AgNO3 solution at 60 °C for 1 h.

[0020] The laser-induced periodic structure and chemically composite coating synergistic antibacterial surface provided by the present invention can be used in the field of material surface modification.

[0021] Preferably, the antibacterial surface can be used in the fields of medical devices, food processing, household appliances, ceramic sanitary wares, packaging plastics, or civil textiles, etc.

[0022] The present invention has the following advantages:

[0023] The present invention provides a surface modification method for reducing the bacterial adhesion on the material surface and improving the antibacterial performance of the material. The prepared material surface has an efficient bacteriostatic effect. Compared with the traditional antibacterial technologies that usually rely on surface topography modification or chemical coatings, each technology solves the problem of bacterial attachment through a single functional approach. Ultrafast laser structuring (such as LIPSS) provides a scalable one-step method. Compared with the performance achieved by using LIPSS or PDA-CS-AgNPs modification alone, the composite Ti-PCA@LIPSS surface shows significant improvement in antibacterial and anti-biofilm performance, with a bactericidal efficiency of 96.9% against Gram-negative Escherichia coli and 91.9% against Gram-positive Staphylococcus aureus. The antibacterial performance of this composite surface exceeds the benchmark performance achieved by using any one of the surface modification methods alone. The composite surface shows excellent anti-biofilm formation ability, providing a feasible approach for large-scale production of antibacterial surfaces with enhanced functions and excellent long-term performance.

[0024] The antibacterial surface of the material prepared by the present invention has a lasting and stable antibacterial effect. Through composite synergy, the antibacterial performance can be significantly improved, and the long-term stability and biocompatibility can be improved. At the same time, it has high heat resistance, convenient use, good chemical stability, a wide range of antibacterial types, and long-term effectiveness. After antibacterial testing, its bacteriostatic effect can still last for a certain period of time.

[0025] The material antibacterial surface provided by the present invention has low preparation cost, is safe and environmentally friendly. All the chemical reagents involved in the composite surface have very low cytotoxicity, are harmless to humans and the environment, and do not produce bacterial drug resistance. This hybrid material can be widely applied in many fields such as medical devices, food processing, household appliances, ceramic sanitary wares, packaging plastics, and civil textiles. Description of the Drawings

[0026] Figure 1 It is the scanning electron microscope (SEM) images of the Ti foil substrate after LIPSS treatment (Ti-LIPSS) and after the construction of the two-in-one composite surface (Ti-PCA@LIPSS) in the present invention.

[0027] Figure 2 It is the two-dimensional Fourier transform of LIPSS and the corresponding power spectrum.

[0028] Figure 3 It is the live-dead fluorescence staining pictures and the statistical results of bacterial adhesion amount of the Ti foil substrate and each modified surface in the present invention after being soaked in two different bacteria for 2 hours.

[0029] Figure 4 It is the bactericidal efficiency of untreated Ti, Ti-LIPSS, Ti-PCA, and Ti-PCA@LIPSS surfaces against Escherichia coli and Staphylococcus aureus at different incubation times in the present invention.

[0030] Figure 5 It is the representative SEM image of the formation of Escherichia coli biofilm after 24-hour incubation time in the present invention.

[0031] Figure 6 It is the representative SEM images of the cell morphology of Escherichia coli on the Ti-PCA surface (a) and the Ti-PCA@LIPSS surfaces (b, c, d) after 24-hour incubation in the present invention. The red circles represent dead bacteria, and the yellow circles represent live bacteria. Detailed Embodiments

[0032] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] Note: The experimental methods in the following embodiments are all conventional methods unless otherwise specified, and are carried out according to the techniques or conditions described in the literature in this field or according to the product specifications. The materials, reagents, etc. used in the following embodiments can be obtained from commercial channels unless otherwise specified.

[0034] Embodiment 1

[0035] This embodiment provides a surface modification method for medical materials, which is completed through three-step modification, specifically as follows:

[0036] Select Ti foil (purchased from GoodFellow, UK) as the material to be modified. First, use Ti foil with a purity of 99.0% and a thickness of 1 mm for laser processing. Before laser treatment, ultrasonically clean a 20 mm × 20 mm × 1 mm Ti substrate with acetone, and then ultrasonically clean it in isopropyl alcohol and deionized (DI) water for 15 minutes respectively to remove any residues. Form low spatial frequency LIPSS through a frequency-doubled Nd:YAG picosecond laser system (Talisker Ultra, Coherent), whose direction is perpendicular to the light polarization, the pulse length is 10 ps, the repetition rate is 50 kHz, the lateral scanning step size (i.e., hatch distance) is 10 μm, and at 1e -2 intensity level, the beam spot diameter on the focal plane is measured to be approximately 50 μm. Use a high-precision motorized stage (Planar DL, Aerotech, USA) to move the substrate relative to the fixed laser beam. The specific processing parameters are shown in Table 1. After laser treatment, ultrasonically clean the substrate with 70% ethanol and deionized water.

[0037] Table 1 Process parameters for LIPSS treatment

[0038]

[0039] The spatial period (Λ) of the LIPSS structure (see c in Figure 1 ) is calculated using two-dimensional fast Fourier transform (2D-FFT) (see a in Figure 2 ), where the two-dimensional Fourier transform and the corresponding power spectrum of the LIPSS are shown in Figure 2 . The positions of the two eccentric peaks (x1 and x2) are determined by the power spectrum and fitted with a Lorentz function (the results are shown in b in Figure 2 ). Among them, x1 = 4.16 μm -1 , x2 = 9.86 μm -1 . The LIPSS period is obtained through the formula Λ = 2 / (x2 - x1), which is 350 - 352 nm, as shown in c in Figure 1 . Immerse all Ti substrates in 10 mol / L HCl solution for 30 minutes to remove the oxide layer, and then clean the substrate with acetone and deionized water. By adding the final concentration of 2 g L at 60 °C -1Dopamine hydrochloride, chitosan CS, and ammonium persulfate (AP) were mixed in HCl solution (pH = 3.8) for 30 minutes to prepare the electroless plating solution. Among them, ammonium persulfate was used as the polymerization initiator, and dopamine hydrochloride was electrolessly plated in a weakly acidic aqueous medium to form polydopamine PDA. In an acidic solution, the composite coating (i.e., the composite coating composed of PDA-CS-AP) was deposited on the LIPSS-treated Ti surface (Ti-LIPSS) by electroless plating. The LIPSS-treated and untreated Ti substrates were immersed in the electroless plating solution at 60 °C for 24 hours to achieve the co-deposition of PDA-CS. After plating, the substrate with the PDA-CS coating was thoroughly rinsed with deionized water and dried in air. Then, silver nanoparticles AgNPs were deposited. Specifically, the coated substrate was immersed in a 0.01 M AgNO3 solution at 60 °C for 1 h. After deposition, the samples were ultrasonically treated in ethanol and deionized water respectively and dried in air. The image of the modified Ti foil (the surface of the Ti-PCA@LIPSS with the PCA composite coating plated on LIPSS) observed under a scanning electron microscope is shown in Figure 1 h in, and i is a partial enlarged view of h. The coated samples (see h, i in Figure 1 ) show submicron morphological changes related to the coating of 170 nm PDA-CS, resulting in a smoother surface. The evenly distributed nanoparticle clusters shown in the figure have an average diameter of 34.6 ± 6 nm after 100 random sampling analyses.

[0040] Among them, in addition to the above-mentioned Ti foil, the modified substrate can also select other medical implant metal substrates, such as titanium metal, stainless steel, alloys, etc., and has significant application prospects in the field of surface modification of materials.

[0041] Traditional silver-coated coatings need to add a sufficient amount of reducing agent to achieve the deposition of silver nanoparticles, while in this technical solution, polydopamine is used, which has strong reducibility itself and can achieve silver film deposition without adding an external reducing agent in the plating solution.

[0042] Experimental Example 1 Determination of the antibacterial effect of the surface-modified material

[0043] The antibacterial effect of the obtained surface-modified material was verified based on the live-dead fluorescence staining method, and the SYTO-9 and PI binding method was selected. Among them, the selected bacteria were E. coli (Escherichia coli) and S. aureus (Staphylococcus aureus).

[0044] The antibacterial efficiency of the substrate was evaluated using bacterial suspensions of Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus strains. The preparation of the bacterial suspension and the bacterial adhesion assay were carried out as follows. Briefly, the frozen stock solutions of E. coli and S. aureus strains were thawed and streaked onto tryptic soy agar (TSA) plates, and then incubated at 37 °C for 12 h. Subsequently, individual bacterial colonies were transferred from the TSA plates to 5 mL of tryptic soy broth (TSB) solution and incubated statically overnight at 37 °C. An aliquot of 500 μL of the bacterial suspension was inoculated into 100 mL of TSB and grown in an incubator at 37 °C. The bacterial growth curve was measured before the antibacterial test. The optical density (OD600) of the bacterial suspension at different growth phases was recorded at 600 nm (measured using a CO800 Biowave). The number of live cells was determined by the viable plate count method, thereby correlating the OD600 measurement with the colony-forming unit (CFU) concentration. The subcultured bacteria were harvested in the mid-exponential phase (optical density OD600 ≈ 0.7), corresponding to the strongest adhesion of the bacteria to the solid surface. For the bacterial adhesion assay, the bacterial suspension was washed twice and diluted with PBS to a concentration of ≈10 7 CFU / mL -1 . Before the test, all substrates were sonicated in 70% ethanol and washed with deionized water for 5 min. Then the substrates were inoculated with 5 mL of E. coli and S. aureus suspensions and incubated at 37 °C at 20 rpm for 2, 6, 12, and 16 h. After incubation, the substrates were gently washed with sterile distilled water and stained with the LIVE / DEAD BacLight Bacterial Viability Kit (L13152, Fisher Scientific, UK) for 15 min in the dark at room temperature. The number of adhered bacteria and the bacterial viability were analyzed using a fluorescence microscope (OLYMPUS BX 41, Japan) and image processing software (ImagePro Plus, Media Cybernetics, USA). The excitation / emission wavelengths used for SYTO9 were 510 nm / 540 nm, and those used for PI were 620 nm / 650 nm. For each substrate, at least six selected microscopic fields were randomly recorded.

[0045] Among them, the calculation formula for the bacterial adhesion reduction rate is as follows:

[0046] Bacterial adhesion reduction rate (%) = (1 - N treated / N as-received ) × 100%

[0047] Statistical calculations were performed on the adhesion rate of bacteria to the surface-modified materials, and the results are shown in Table 2. The fluorescence staining results are shown as a in Figure 3 ; Figure 3In b and c, the adhesion counts of b) Escherichia coli and c) Staphylococcus aureus on the untreated Ti, Ti-LIPSS, Ti-PCA, and Ti-PCA@LIPSS surfaces after 2 hours of incubation are shown respectively. Here, 'Ti-LIPSS' represents the surface after only laser etching; 'Ti-PCA' represents the surface modified only with the composite coating PCA; 'Ti-PCA@LIPSS' represents the two-in-one surface containing both LIPSS and PCA coatings. The antibacterial experimental results show that the composite surface (Ti-PCA@LIPSS) prepared by this method exhibits more effective antibacterial initial adhesion performance than any of the previous single-method modifications within 2 hours.

[0048] Table 2 Comparison of antibacterial adhesion rates within 2 hours

[0049] 2h inhibition rate Ti-LIPSS Ti-PCA Ti-PCA@LIPSS E.coli (Escherichia coli) 70.9％ 69.9％ 88.6％ S.aureus (Staphylococcus aureus) 53.8％ 35.3％ 80％

[0050] After a 16-hour bacterial immersion experiment on all surfaces, the adhered bacteria on the surfaces were stained with live / dead staining and counted after immersion, and the bactericidal efficiency (BE) of each surface was calculated. BE is calculated as the ratio of red to red-green fluorescence, representing the proportion of dead bacterial cells (red fluorescence) to the entire population of live and dead bacterial cells (green and red fluorescence).

[0051] The calculation results of the bactericidal efficiency of each surface are shown in Figure 4 as follows, where Figure 4 a and b in it are the calculation results of the bactericidal efficiency of Escherichia coli and Staphylococcus aureus after immersion respectively. It can be seen that the untreated Ti surface maintained the lowest bactericidal efficiency of 20% during the 2-hour and 16-hour incubation periods. Notably, within the 16-hour incubation period, the bactericidal efficiency of Ti-LIPSS against Escherichia coli gradually decreased from 69.1% to 40.4% (see Figure 4 a) in it). At the early stage of planktonic bacteria attachment, the high bactericidal efficiency can be attributed to the bacteria-expelling effect of the LIPSS topography. For longer incubation times, the performance decline can be attributed to surface contamination by dead cells, resulting in increased bacterial retention. For Staphylococcus aureus, the untreated Ti showed a low bactericidal efficiency of 11% during the 2-hour and 6-hour incubation periods. Although this value gradually increased and reached approximately 27% within 16 h, it was still lower than the other three surface groups. The bactericidal efficiency of Ti-LIPSS increased from 28.9% at 2-hour incubation to 38.3% at 6-hour incubation, and no further increase was observed during the longer incubation period (see Figure 4b) in. This is consistent with the effect of the LIPSS spatial period discussed above. The Ti-PCA surface has a fairly stable bactericidal performance during the incubation time of 6 to 16 hours, with an average efficiency of about 81% against Escherichia coli and about 67% against Staphylococcus aureus, which is mainly attributed to the bactericidal effect of Ag+. During the initial 2-hour incubation time, the bactericidal efficiency against Escherichia coli reached 74.2%, and the bactericidal efficiency against Staphylococcus aureus reached 41%. This relatively low performance may be attributed to the slow release of Ag+ ions. This experiment shows that changing the surface topography can accelerate the release of Ag+ ions by up to 2.5 times, enhancing the antibacterial efficacy. The Ti-PCA@LIPSS group obtained the highest bactericidal performance, and the maximum bactericidal efficiencies against Escherichia coli and Staphylococcus aureus were 96.6% and 91.9% respectively during the 16-hour incubation period. This further confirms that the multifunctional surface modification developed in this work effectively enhances the antibacterial effect through complementary antibacterial pathways.

[0052] Experimental Example 2 Determination of the anti-biofilm formation effect of the surface-modified material

[0053] To verify the ability of the prepared modified surface in anti-biofilm formation, aliquots of 5 mL of an Escherichia coli suspension with a concentration of 2×10 7 CFU / mL were used to evaluate the anti-biofilm performance of the substrate. The substrate was incubated in a 6-well plate at 37 °C and 20 rpm for 24 hours. Then the substrate was rinsed twice with PBS and immersed in a fixative solution of 2.5% glutaraldehyde (Sigma-Aldrich, UK) at 4 °C for 2 hours. Then it was dehydrated by continuous immersion in an ethanol gradient with increasing concentrations (20%, 30%, 50%, 70%, 90% and 100%). In the experiment, the incubation time was extended to 24 hours. Before EM imaging, a thin layer of gold (Au) was coated on the substrate, and then the bacterial adhesion on the surface of each modified material was observed by scanning electron microscopy. The results Figure 5 are shown, where a, b, c, d are the electron microscopy images at 1000X, and e, f, g, h are the electron microscopy images at 3000X. The untreated Ti and Ti-LIPSS surfaces showed a large amount of bacterial adhesion and biofilm formation (see Figure 5 a, b, e, f therein). Compared with the untreated Ti or Ti-LIPSS surfaces, the PCA-modified surface showed limited Escherichia coli aggregation and excellent resistance to biofilm formation (see Figure 5 c, g therein). Some cases of bacterial membrane deformation can be seen in Figure 5 g (see also Figure 6 a therein), indicating the loss of integrity of the Escherichia coli cell membrane leading to its death. The results of the Ti-PCA@LIPSS surface (see Figure 5d) and h) in [reference] confirm that it can effectively inhibit bacterial attachment and biofilm formation within a 24-hour incubation period. The high-magnification images of Ti-PCA@LIPSS further demonstrate limited bacterial colonization, with single bacteria or aggregates of two bacteria detected on the surface (see Figure 6 b-d) in [reference]. It can be seen that compared with either surface, no obvious biofilm formation occurs on the Ti-PCA@LIPSS composite surface constructed in the present invention, indicating that after surface modification of the material, the formation of bacterial biofilms can be significantly inhibited. This modification method can be applied in the field of material surfaces, especially having potential application prospects in the modification of medical implant materials.

[0054] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be construed as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and alternatives to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. An antibacterial surface synergistically composed of laser-induced periodic structures and chemical composite coatings, characterized in that, The antibacterial surface comprises a PCA composite coating obtained by laser treatment and electroless plating.

2. The antibacterial surface according to claim 1, characterized in that, The periodic surface structure obtained by the laser treatment is low spatial frequency LIPSS with a period of 350 nm and a direction perpendicular to the light polarization.

3. The antibacterial surface according to claim 1, wherein, The PCA composite coating is a co-deposition comprising polydopamine PDA, chitosan CS, and silver nanoparticles AgNPs.

4. The antibacterial surface according to claim 1, characterized in that, The substrate of the antibacterial surface is selected from metallic titanium, stainless steel, alloys, or medical implant materials.

5. The preparation method of the antibacterial surface according to any one of claims 1-4, characterized in that, It includes the following steps: S1: The substrate to be modified is subjected to laser treatment to obtain a LIPSS surface with a period of 350 nm. S2: The obtained LIPSS surface is subjected to electroless plating in an electroless plating solution to complete the co-deposition of polydopamine PDA and chitosan CS. S3: Silver nanoparticles AgNPs are deposited on the material obtained by the electroless plating to obtain the antibacterial surface. Among them, the electroless plating solution is prepared by mixing dopamine hydrochloride, chitosan CS and ammonium persulfate AP with a final concentration of 2 g / L in an HCl solution with a pH of 3.8 at 60 °C. -1 ​ 6. The preparation method according to claim 5, characterized in that, S1 further includes ultrasonic cleaning of the substrate to be modified before the laser treatment and removal of the oxide layer after the laser treatment.

7. The preparation method according to claim 5, characterized in that, The electroless plating in S2 is soaking in an electroless plating solution at 60 °C for 24 hours.

8. The preparation method according to claim 5, characterized in that, The deposition of silver nanoparticles AgNPs in S3 is soaking in a 0.01 M AgNO3 solution at 60 °C for 1 h.

9. Use of the antibacterial surface according to any one of claims 1-4 in the field of material surface modification. The application according to claim 9, characterized in that, The field includes the fields of medical devices, food processing, household appliances, ceramic sanitary wares, packaging plastics, or civil textiles.

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