Pearson’s correlation coefficient values.

Recorded Pearson’s correlation coefficient values for each skin section MALDI imaging analysis based on comparing its m/z 304 ion heat map to its m/z 332 ion heat map. (XLSX)</p

Observed average depth of BZK into the dermal layer of skin.

Observed average depth of BZK into the dermal layer of skin.</p

Total ion penetration into human skin.

(A) Average penetration observed of ion m/z 304 into the skin. (B) Average penetration observed of ion m/z 332 into the skin. Both are showing the observed thickness of the epidermis in purple and continued ion depth into the dermis in pink. (TIF)</p

Epidermal thicknesses of each specific skin location based on treatment group.

Epidermal thicknesses of each specific skin location based on treatment group.</p

Treated skin single ion heat maps.

Selected ion heat maps of (A) BZK in water, (B) water, (C) Solution 1, (D) Solution 2, (E) BZK + citric acid (pH 4.7), (F) BZK + caprylyl glycol, (G) BZK + vitamin E. The ion m/z 304.30 is shown in red and ion m/z 332.33 in blue. All yellow scale bars represent 2 mm. Skin is oriented with epidermis on the right side. Dotted lines are the selected regions of interest drawn along the edges of the skin.</p

Imaging of gelatin compared to negative and positive control.

Ion heat maps of gelatin without skin, negative control, and positive control. (A-C) Selected ions of m/z 172.06 ±0.43, (D-F) ion m/z 212.04 ± 0.53, (G-I) ion m/z 335.14 ± 0.84, (J-L) and ion m/z 379.13 ±0.95 are all CHCA matrix ions and are represented with purple. (M-O) Ions heat maps of ion m/z 304.30 ±0.76 (BZK C12) in red. (P-R) Ion heat maps m/z 332.33 ± 0.83 (BZK C14) in blue. (TIF)</p

Collected spectra of all matrix, excipients, and solutions.

Collected mass spectra of (A) CHCA matrix, (B) sDHB matrix, (C) 0.123% BZK solution, (D) citric acid, (E) 1.0% caprylyl glycol solution, (F) 0.1% vitamin E solution, (G) BZK + citric acid treatment solution, (H) BZK + caprylyl glycol, (I) BZK + vitamin E, (J) Solution 1, and (K) Solution 2. All were collected in reflectron positive mode with 5,000 laser pulses. Mass range was set to m/z 100–600. All solutions were spotted with 40 mg/mL CHCA in acetone as the matrix. Labeled peaks of m/z 172, 212, 335, and 379 were all found to be CHCA matrix peaks. (TIF)</p

Epidermis thickness.

(A) Epidermis thicknesses observed for each of the different skin types for each of the treatment groups. Significance was determine using multiple paired t-test (B) Average epidermis thickness for each of the different treatment groups. Significance was determined with one-way ANOVA. Significance is noted with P (TIF)</p

General penetration of BZK ion heat maps.

Selected ion heat maps of (A) BZK in water, (B) water, (C) Solution 1, (D) Solution 2, (E) BZK + citric acid (pH 4.7), (F) BZK + caprylyl glycol, (G) BZK + vitamin E. The ion m/z 304.30 is shown in red and ion m/z 332.33 in blue. All yellow scale bars represent 2 mm. Skin is oriented with epidermis on the right side. Dotted lines are the selected regions of interest drawn along the edge of the skin.</p

General BZK penetration into dermis.

Graph showing the determined BZK ion penetration based on ion heat maps showing both ion m/z 304 and ion m/z 332. One-way ANOVA was carried out to determine significance where P<0.05 *, P<0.01 **, P< 0.001 ***, and P<0.0001 ****.</p